FEMS Microbiol Lett, 1997 Mar 15, 148(2), 189 - 95 Listeria monocytogenes infection of HeLa cells results in listeriolysin O-mediated transient activation of the Raf-MEK-MAP kinase pathway; Weiglein I et al.; In this study we investigated the effect of Listeria monocytogenes infection on the activation of the Raf-MEK-MAP kinase pathway in eukaryotic host cells . HeLa cell infection with L . monocytogenes EGD resulted in a rapid, but transient, phosphorylation of the MAP kinases erk-1 and erk-2, a transient phosphorylation of the MAP kinase kinase MEK-1, and a transient activation of the MAP kinase kinase kinase Raf . In parallel to the transient phosphorylation of the MAP kinases, we detected induced expression of the MAP kinase phosphatase MKP-1 . Additionally we present evidence that listeriolysin O is the inducing agent for activation of the Raf-MEK-MAP kinase pathway. J Exp Med, 1997 Mar 3, 185(5), 921 - 31 Crucial role of interferon consensus sequence binding protein, but neither of interferon regulatory factor 1 nor of nitric oxide synthesis for protection against murine listeriosis; Fehr T et al.; Listeria monocytogenes is widely used as a model to study immune responses against intracellular bacteria . It has been shown that neutrophils and macrophages play an important role to restrict bacterial replication in the early phase of primary infection in mice, and that the cytokines interferon-gamma (IFN-gamma) and tumor necrosis factor-alpha (TNF-alpha) are essential for protection . However, the involved signaling pathways and effector mechanisms are still poorly understood . This study investigated mouse strains deficient for the IFN-dependent transcription factors interferon consensus sequence binding protein (ICSBP), interferon regulatory factor (IRF) 1 or 2 for their capacity to eliminate Listeria in vivo and in vitro and for production of inducible reactive nitrogen intermediates (RNI) or reactive oxygen intermediates (ROI) in macrophages . ICSBP-/- and to a lesser degree also IRF2-/- mice were highly susceptible to Listeria infection . This correlated with impaired elimination of Listeria from infected peritoneal macrophage (PEM) cultures stimulated with IFN-gamma in vitro; in addition these cultures showed reduced and delayed oxidative burst upon IFN-gamma stimulation, whereas nitric oxide production was normal . In contrast, mice deficient for IRF1 were not able to produce nitric oxide, but they efficiently controlled Listeria in vivo and in vitro . These results indicate that (a) the ICSBP/IRF2 complex is essential for IFN-gamma-mediated protection against Listeria and that (b) ROI together with additional still unknown effector mechanisms may be responsible for the anti-Listeria activity of macrophages, whereas IRF1-induced RNI are not limiting. Int J Food Microbiol, 1997 Mar 3, 34(3), 319 - 27 Differences in pathogenicity for chick embryos and growth kinetics at 37 degrees C between clinical and meat isolates of Listeria monocytogenes previously stored at 4 degrees C; Avery SM et al.; Fifteen clinical strains of Listeria monocytogenes (eight strains of serogroup 4 and seven strains of serogroup 1) and 15 meat isolates (all serogroup 1) were stored with no growth in phosphate-buffered saline (pH 7.0) at 4 degrees C for 4 weeks . Pathogenicity for 14 day old chick embryos and growth kinetics in brain heart infusion (BHI) broth at 37 degrees C of the strains were determined before and after storage . Although no differences in pathogenicity between clinical and meat strains were found when tested as fresh cultures significant differences became apparent after cold storage . Firstly, the pathogenicity of clinical strains was not affected by storage, whereas the average mortality of embryos inoculated with meat strains decreased from 98.7 to 68.0% . Secondly, clinical strains subcultured at 37 degrees C had a significantly shorter average lag phase than meat strains after cold storage . The results of this study indicate that strains that caused human listeriosis have a higher resistance to the effects of unfavourable storage conditions than meat strains with respect to pathogenicity and lag phase duration at body temperature. Int J Food Microbiol, 1997 Mar 3, 34(3), 221 - 32 Predictive modelling of growth of Listeria monocytogenes . The effects on growth of NaCl, pH, storage temperature and NaNO2; McClure PJ et al.; The effect of NaCl concentration (5.0 115.0 g/l) . pH value (4.0-7.2), temperature (1-35 degrees C) and NaNO2 concentration (0 200 mg/l) on the growth responses of Listeria monocytogenes, in laboratory medium was investigated . The growth curves generated within this matrix of conditions were fitted using the function of Baranyi and Roberts (1994) and the growth responses modelled using a quadratic polynomial to produce response surfaces . Growth curves could then be regenerated for any set of conditions within the experimental matrix and values predicted for the growth rate, doubling time, lag time and time to 1000-fold increase . The model was validated using data from published literature and was found to give realistic predictions for doubling times in foods, including meat and meat products, milk, dairy products and vegetables . Predictions from this model (Baranyi and Roberts . 1994) compared favourably with those from the models of Buchanan and Phillips (1990), Murphy et al . (1996) and the Food MicroModel. Curr Biol, 1997 Mar 1, 7(3), R164 - 7 Cell motility: complex dynamics at the leading edge; Machesky LM; The intracellular pathogen Listeria monocytogenes is a useful model for general actin-based cell motility, because it recruits host actin and associated proteins for movement . Recent data have shown that these associated proteins include the Ena/VASP family of proteins and the actin-related proteins Arp2 and Arp3. Vaccine, 1997 Mar, 15(4), 433 - 40 Influenza-specific immunity induced by recombinant Listeria monocytogenes vaccines; Ikonomidis G et al.; In this study, we evaluate two Listeria monocytogenes strains that express influenza nucleoprotein (NP) sequences for their ability to protect against challenge with influenza-virus . The construction of one strain, which expresses only the Kd restricted NP epitope (NP 147-155), is described in this study; the other strain, which expresses the full NP sequence in the form of a fusion protein, has been described previously . The ability of the two strains to present the Kd restricted NP epitope in vitro and induce NP-specific CTL in vivo is also described . Mice immunized by the intravenous route with either strain cleared a subsequent (3 weeks post-immunization) influenza virus infection more rapidly as indicated by reduced virus titers in the lungs 5 days after challenge . Efficacy of both recombinant L . monocytogenes strains as vaccines in this system was equivalent and equal to that of recombinant vaccinia expressing NP. Vaccine, 1997 Mar, 15(4), 395 - 401 Effective adjuvants for the induction of antigen-specific delayed-type hypersensitivity; Baldridge JR et al.; Vaccines utilizing poorly immunogenic subunit antigens are dependent upon adjuvants to drive the appropriate T cell responses . In an effort to determine the ability of several adjuvants to promote cell-mediated immunity (CMI), we assessed delayed-type hypersensitivity (DTH) in mice inoculated with heat-killed Listeria monocytogenes (HKLM) vaccines . The vaccines were formulated as oil-in-water emulsions containing one or more of the following bacterial-derived immunostimulators: MPL immunostimulant, a monophosphoryl lipid A preparation, synthetic trehalose dicorynomycolate (TDCM) and Mycobacterium phlei cell wall skeleton (CWS) . Oil-in-water emulsions containing HKLM without adjuvants did not induce DTH responsiveness in mice . The incorporation of TDCM, or MPL plus TDCM and/or CWS to the formulation enabled the HKLM vaccine to stimulate CMI characterized by DTH responsiveness . Following antigen challenge the resulting increases in footpad thickness ranged from 15-20% and were comparable to the DTH driven by complete Freund's adjuvant . Adjuvants composed of MPL/TDCM and MPL/TDCM/CWS induced responses equivalent to those measured in mice immunized with viable L . monocytogenes, and the responses remained at these levels for at least 2 months . Furthermore, in vivo depletion of CD4+ T cells, but not CD8+ T cells, abrogated the induction and expression of DTH, indicating that the response is mediated by CD4+ T cells. J Med Microbiol, 1997 Mar, 46(3), 239 - 50 Neutrophils and tumour necrosis factor-alpha are important for controlling early gastrointestinal stages of experimental murine listeriosis; Conlan JW; The present study examined the need for neutrophils and tumour necrosis factor-alpha (TNF alpha) for early defence against gut infection with the enteroinvasive, facultative intracellular bacterial pathogen, Listeria monocytogenes . Mice were treated with a neutrophil-depleting monoclonal antibody (MAb) or a MAb directed against TNF alpha, and the consequences of these treatments on the course of orally initiated infection with the pathogen were monitored . By day 3, orally initiated L . monocytogenes infection in mice treated with either MAb was severely exacerbated to the extent that up to 5000-fold more listeriae were recovered from the walls of the stomach, small intestine, caecum or large intestine of treated mice than from controls . Systemic infection resulting from the ingestion of L . monocytogenes was also severely enhanced in mice treated with these MAbs . Therefore, the results showed that neutrophils and TNF alpha have a critical role in the early defence against enteroinvasive L . monocytogenes infection initiated by a natural (in this case the oral) route, as well as in the control of subsequent systemic infection. J Cell Sci, 1997 Mar, 110 ( Pt 6), 731 - 43 Internalized Listeria monocytogenes modulates intracellular trafficking and delays maturation of the phagosome; Alvarez-Dominguez C et al.; Previous studies have shown that early phagosome-endosome fusion events following phagocytosis of Listeria monocytogenes are modulated by the live organism . In the present study, we have characterized more fully the intracellular pathway of dead and live Listeria phagosomes . To examine access of endosomal and lysosomal markers to phagosomes containing live and dead Listeria, quantitative electron microscopy was carried out with intact cells using internalized BSA-gold as a marker to quantify transfer of solute from endosomal and lysosomal compartments to phagosomes . To monitor the protein composition of phagosomal membranes and to quantify transfer of HRP from endosomes and lysosomes to phagosomes, highly enriched phagosomes containing live and dead Listeria were isolated . Enriched phagosomal membranes were used for western blotting experiments with endosomal and lysosomal markers . In this study, we used a listeriolysin-deficient mutant, Listeria(hly-), that is retained within the phagosome following phagocytosis . Western blotting experiments indicate that early endosomal markers (mannose receptor, transferrin receptor) and key fusion factors necessary for early events (NSF, alpha/beta-SNAP) but not late endosomal markers (cation dependent mannose 6-phosphate receptor) or lysosomal proteins (cathepsin D or lamp-1) accumulate on the live-Listeria phagosomal membranes . On the contrary, phagosomes containing dead-Listeria are readily accessible by both endocytic and lysosomal markers . Studies with radiolabeled dead- and live-Listeria(hly-) indicate that, following phagocytosis, degradation of the live microorganism is substantially delayed . These findings indicate that dead-Listeria containing phagosomes rapidly mature to a phagolysosomal stage whereas live-Listeria(hly-) prevents maturation, in part, by avoiding fusion with lysosomes . The data suggest that by delaying phagosome maturation and subsequent degradation, Listeria prolongs survival inside the phagosome/endosome assuring bacterial viability as a prelude to escape into the cytoplasm. Lett Appl Microbiol, 1997 Mar, 24(3), 166 - 8 Nucleotide sequence analysis of two virulence-associated genes in Listeria monocytogenes serotype 1/2b and comparison with the same genes in other serotypes important in human disease; Vines A et al.; The nucleotide sequences of the hly and plcA genes (encoding listeriolysin, a thiol-activated cytolysin and a non-specific phospholipase C, respectively) were determined for two strains of Listeria monocytogenes serotype 1/2b . The deduced amino acid sequences for listeriolysin were identical for the two strains and identical to that of listeriolysin from serotype 4b . The two serotype 1/2b strains differed in one amino acid (histidine vs asparagine) in the deduced amino acid sequence for phosopholipase C. Mol Microbiol, 1997 Mar, 23(5), 1075 - 85 Carbon-source regulation of virulence gene expression in Listeria monocytogenes; Milenbachs AA et al.; All known virulence genes of Listeria monocytogenes are under positive regulation by the transcription factor PrfA . Previous work employing the L . monocytogenes strain NCTC7973 suggested that the disaccharide cellobiose might serve as a specific "signature molecule' which functions to prevent activation of the PrfA-controlled regulon in a soil environment . We have examined three other L . monocytogenes strains, 10403S, LO28 and EGD, all commonly regarded as wild-type isolates, and find that NCTC7973 is anomalous with respect to the effect of carbohydrates on the expression of PrfA-controlled gene expression . In the case of 10403S, LO28 and EGD, several other readily metabolized mono- and disaccharides are as effective as cellobiose in repressing expression of the PrfA-controlled gene hly, indicating that the cellobiose effect is not specific, and suggesting that NCTC7973 may be a partially deregulated variant . Moreover, concentrations of cellobiose and other sugars required for repression of hly expression (> 1 mM) were found to significantly enhance growth of L . monocytogenes cultures, suggesting that the repression phenomenon probably results from a metabolic effect of sugar utilization rather than a signal-sensing response . Thus the previously reported cellobiose effect may reflect an aspect of a more global mechanism of catabolite repression in L . monocytogenes . Although cellobiose represses expression of hly and plcA at the level of transcript accumulation, quantitative Western blot analysis indicates that cellobiose has no effect on PrfA levels . These results are consistent with a model in which PrfA activity is controlled by interaction with a hypothetical cofactor, the synthesis or depletion of which is responsive to the presence of readily metabolized carbohydrates. Appl Environ Microbiol, 1997 Mar, 63(3), 1155 - 9 Protamine-induced permeabilization of cell envelopes of gram-positive and gram-negative bacteria; Johansen C et al.; The inhibitory effect of the cationic peptide protamine on Listeria monocytogenes, Escherichia coli, and Shewanella putrefaciens has been studied in detail . The addition of protamine (10 to 1,000 micrograms/ml) resulted in inhibition of oxygen consumption after less than 1 min and loss of intracellular carboxyfluorescein and ATP after 2 to 5 min . Maximum antibacterial activity was reached at alkaline pH and in the absence of divalent cations . The efficient permeabilization of cell envelopes of both gram-positive and gram-negative bacteria suggests that protamine causes a general disruption of the cell envelope, leading to a rapid and nonspecific efflux of low- and high-molecular-weight compounds. Appl Environ Microbiol, 1997 Mar, 63(3), 1077 - 82 DNA fragments from regions involved in surface antigen expression specifically identify Listeria monocytogenes serovar 4 and a subset thereof: cluster IIB (serotypes 4b, 4d, and 4e); Lei XH et al.; Listeria monocytogenes serotype 4b has frequently been implicated in sporadic as well as epidemic listeriosis . On the basis of pulsed-field fingerprinting, serotype 4b strains, along with strains of serotypes 4d and 4e, constitute one genomic cluster (IIB) . We have identified two genomic regions essential for the expression of surface antigens which previously were shown to be specific to cluster IIB strains . A DNA probe of 1.1 kb derived from one of the regions (probe 1) hybridized only with strains of serotypes 4b, 4d, and 4e in Southern blots and dot blots . A different DNA probe of 0.3 kb (probe 2), derived from the other region, hybridized with all serovar 4 strains (serotypes 4b, 4a, 4c, 4d, and 4e) . All other L . monocytogenes serotypes were negative with probe 1 or 2 . Use of probe 1 in Southern blots of EcoRI-digested genomic DNA revealed a restriction fragment length polymorphism in serotype 4b strains, with the hybridizing EcoRI fragments being 4.5 kb (strains of the epidemic clone) and either 4.5 or 5.0 kb (all other serotype 4b strains) . Although the probes hybridized with a special group of Listeria innocua strains which also expressed the surface antigens, the latter could be readily distinguished by the size of the hybridizing EcoRI fragment with probe 1 (ca . 2.2 kb) . These data suggest that the combined use of these probes with L . monocytogenes can readily and specifically identify cluster IIB strains as well as the entire serovar 4 complex. J Bacteriol, 1997 Mar, 179(5), 1533 - 40 A Gly145Ser substitution in the transcriptional activator PrfA causes constitutive overexpression of virulence factors in Listeria monocytogenes; Ripio MT et al.; Virulence genes in Listeria monocytogenes are coordinately expressed under the control of the transcriptional activator PrfA, encoded by prfA, a member of the cyclic AMP (cAMP) receptor protein (CRP)/FNR family of bacterial regulators . Strain P14-A is a spontaneous mutant of L . monocytogenes serovar 4b which produces elevated levels of virulence factors (M . T . Ripio, G . Dominguez-Bernal, M . Suarez, K . Brehm, P . Berche, and J . A . Vazquez-Boland, Res . Microbiol . 147:371-384, 1996) . Here we report that P14-A and other variant strains with the same phenotype carry a point mutation in codon 145 of prfA, leading to a Gly-->Ser substitution . trans-complementation experiments with PrfA-deficient mutants demonstrated that the Gly145Ser prfA allele causes overexpression of virulence factors in L . monocytogenes, to the levels found in the virulence factor-overexpressing variants . In strain P14-A with a chromosomal Glyl45Ser prfA background, transcription of prfA and of PrfA-dependent virulence genes remained constitutively high under culture conditions in which virulence factor expression is downregulated in wild-type L . monocytogenes . The Glyl45Ser substitution is located in a PrfA stretch (residues 141 to 151) showing high sequence similarity to the D alpha-helix of CRP . Interestingly, well-characterized crp* mutations, which make CRP functionally active in the absence of cAMP, map in this region (i.e., Gly141Ser and Ala144Thr substitutions) . By analogy with the CRP model, the phenotype conferred to L . monocytogenes by the Gly145Ser substitution in PrfA could be due to the mutant regulatory protein being locked in a transcriptionally active, cofactor-independent conformational state . Our observations allow the construction of a model for PrfA-dependent virulence gene regulation in which the levels of virulence factor expression depend primarily on the conformational state of the PrfA protein, which alternates between active and inactive forms according to its interaction with an environmentally regulated signal molecule or cofactor. Infect Immun, 1997 Mar, 65(3), 1095 - 7 Involvement of tubulin and inhibitory G proteins in the interaction of Listeria monocytogenes with mouse hepatocytes; Buchwalow IB et al.; Intracellular and cell-to-cell spread of Listeria monocytogenes has been considered exclusively actin dependent . By immunocytochemical techniques, we provide evidence for an involvement of inhibitory G proteins and tubulin in "comet tail" formation in L . monocytogenes-infected mouse hepatocytes. Infect Immun, 1997 Mar, 65(3), 986 - 93 Elimination of resident macrophages from the livers and spleens of immune mice impairs acquired resistance against a secondary Listeria monocytogenes infection; Samsom JN et al.; During a secondary Listeria monocytogenes infection in mice, the bacteria are eliminated more rapidly from the liver and spleen than during a primary infection . This acquired resistance against a secondary infection is dependent on T lymphocytes, which induce enhanced elimination of bacteria via stimulation of effector cells such as neutrophils, resident macrophages, exudate macrophages, and hepatocytes . The aim of the present study was to determine the role of the resident macrophages in acquired resistance against a secondary L . monocytogenes infection in mice . Mice which had recovered from a sublethal primary infection with 0.1 50% lethal dose (LD50) of L . monocytogenes intravenously (i.v.), i.e., immune mice, received a challenge of 1 LD50 of L . monocytogenes i.v . to induce a secondary infection . At 2 days prior to challenge, immune mice were given an i.v . injection of liposomes containing dichloromethylene-diphosphonate (L-Cl2MDP) to selectively eliminate resident macrophages from the liver and spleen . Control immune mice received either phosphate-buffered saline (PBS) or liposomes containing PBS (L-PBS) . Treatment of mice with L-Cl2MDP effectively eliminated resident macrophages from the liver and spleen but did not affect the number of granulocytes, monocytes, or lymphocytes in peripheral blood or their migration to a site of inflammation . Phagocytosis and killing of L . monocytogenes by peritoneal exudate cells elicited with heat-killed L . monocytogenes were similar in all groups of immune mice . On day 3 of a secondary infection, the number of L . monocytogenes organisms in the livers and spleens of L-Cl2MDP-treated immune mice was 4 log10 units higher than in immune mice treated with PBS or L-PBS . The concentration of reactive nitrogen intermediates in plasma, a measure of the severity of infection, was 70-fold higher for L-Cl2MDP-treated immune mice than for PBS- or L-PBS-treated immune mice . Treatment with L-Cl2MDP significantly increased the number of inflammatory foci in the liver and spleen, decreased their size, and affected their structure . From these results, we conclude that resident macrophages are required for the expression of acquired resistance against a secondary L . monocytogenes infection in mice. Infect Immun, 1997 Mar, 65(3), 978 - 85 Porcine polymorphonuclear leukocytes generate extracellular microbicidal activity by elastase-mediated activation of secreted proprotegrins; Panyutich A et al.; Antimicrobial peptides of several structural classes have been found in phagocytes and epithelial cells of many animals . The broadly microbicidal protegrins (PG1, -2, and -3) were originally isolated as 16 to 18-amino-acid peptides from pig neutrophil lysates, but the corresponding cDNA sequences encoded much larger precursors that belonged to the cathelicidin family of antimicrobial peptides . We explored the storage, secretion, and microbicidal activation of protegrins in porcine neutrophils and in a model system consisting of recombinant proprotegrin 3 (pPG3) and various serine proteases and their inhibitors . Protegrins were stored in neutrophils as inactive proforms that were cleaved by neutrophil elastase to mature protegrins during the preparation of granule lysate and during phorbol myristate acetate-stimulated granule secretion from intact neutrophils . Recombinant pPG3 was efficiently cleaved by trace amounts of human neutrophil elastase or equivalent amounts of elastase activity from porcine neutrophils, but pPG3 was relatively resistant to porcine pancreatic elastase or human neutrophil cathepsin G . The recombinant pPG3 and neutrophil proprotegrins lacked microbicidal activity, but the mature protegrins generated in the elastase-mediated cleavage reaction were as active against Listeria monocytogenes as the chemically synthesized protegrin . The secretion and elastase-mediated activation of proprotegrins accounted for much of the stable microbicidal activity of porcine neutrophil secretions against L . monocytogenes . Secreted proprotegrins and trace amounts of elastase constitute a binary microbicidal system that is likely to contribute to the antimicrobial activity of porcine inflammatory fluids. J Immunol, 1997 Mar 1, 158(5), 2259 - 67 Both innate and acquired immunity to Listeria monocytogenes infection are increased in IL-10-deficient mice; Dai WJ et al.; IL-10-deficient mice were highly resistant to Listeria monocytogenes during the course of infection . An increased innate immunity was suggested by reduced bacterial burdens (as much as 50-fold) early (days 2 and 3) in the infection, as compared with control mice . In addition, in vitro stimulation of both IL-10-deficient peritoneal exudate cells and spleen cells with heat-killed Listeria resulted in a dramatically enhanced proinflammatory cytokine response (e.g., IL-12, IFN-gamma, TNF-alpha, IL-1alpha, and IL-6) . During later stages of a primary Listeria infection, the reduced bacterial burden in the infected organs of IL-10-deficient mice was accompanied by decreased tissue damage and earlier clearance of the pathogen, as well as a stronger Th1 polarization . The absence of IL-10 did not influence membrane-bound factors that stimulate Th cell responses, demonstrated by the finding of normal MHC class II, B7.1, and B7.2 surface expression on F4/80+ macrophages in vivo . IL-10-deficient mice were also more resistant to a secondary infection, accompanied by an enhanced Th1 response . The results presented in this work demonstrate that the absence of IL-10 augments innate and acquired immunity during primary and secondary L . monocytogenes infection by up-regulating proinflammatory type 1 cytokine responses . The resulting protective Th1 responses lead to an effective reduction of bacterial growth and tissue destruction and to an earlier clearance of the bacteria . The physiologic role of IL-10 during L . monocytogenes infection studies is discussed and compared with pathogenic infections that induce a more systemic cytokine response in IL-10-deficient mice. Biochem Biophys Res Commun, 1997 Feb 24, 231(3), 686 - 91 ABM-1 and ABM-2 homology sequences: consensus docking sites for actin-based motility defined by oligoproline regions in Listeria ActA surface protein and human VASP; Purich DL et al.; Actin-based motility involves a cascade of binding interactions designed to assemble actin regulatory proteins into functional locomotory units . Listeria ActA surface protein contains a series of nearly identical EFPPPPTDE-type oligoproline sequences for binding vasodilator-stimulated phosphoprotein (VASP) . The latter is a tetrameric protein with numerous GPP-PPP docking sites for profilin, a 15 kDa regulatory protein that promotes actin filament assembly . Analysis of known actin regulatory proteins led to the identification of distinct Actin-Based Motility homology sequences ABM-1; (D/E)FPPPPX(D/E); and ABM-2, XPPPPP (where X denotes G, A, L, and S). J Biol Chem, 1997 Feb 7, 272(6), 3259 - 65 A novel non-heme iron-binding ferritin related to the DNA-binding proteins of the Dps family in Listeria innocua; Bozzi M et al.; A multimeric protein that behaves functionally as an authentic ferritin has been isolated from the Gram-positive bacterium Listeria innocua . The purified protein has a molecular mass of about 240,000 Da and is composed of a single type of subunit (18,000 Da) . L . innocua ferritin is able to oxidize and sequester about 500 iron atoms inside the protein cage . The primary structure reveals a high similarity to the DNA-binding proteins designated Dps . Among the proven ferritins, the most similar sequences are those of mammalian L chains that appear to share with L . innocua ferritin the negatively charged amino acids corresponding to the iron nucleation site . In L . innocua ferritin, an additional aspartyl residue may provide a strong complexing capacity that renders the iron oxidation and incorporation processes extremely efficient . This study provides the first experimental evidence for the existence of a non-heme bacterial ferritin that is related to Dps proteins, a finding that lends support to the recent suggestion of a common evolutionary origin of these two protein families. Scott Med J . 1997 Feb;42(1):18. Listeria monocytogenes: a rare cause of pleural effusion in a patient with congestive cardiac failure; Hood S et al.; We report the case of a 65 year old immunocompetent man with a listerial pleural effusion . Infection of the pulmonary parenchyma and pleura with listeria monocytogenes has been reported in small numbers of immunocompromised patients but there have been only two previous reports of pulmonary listeria in non-compromised hosts. Mol Biotechnol, 1997 Feb, 7(1), 85 - 8 Detection and identification of Listeria monocytogenes from milk and cheese by a single-step PCR; Manzano M et al.; Primers of iap gene were used as a target to develop a PCR technique for detecting Listeria monocytogenes in milk and cheese . The PCR technique gives good results in the detection of Listeria monocytogenes either in artificially or naturally contaminated foodstuffs and has a high sensitivity and specificity . Application of this rapid diagnostic tool could provide further information about the spread of L . monocytogenes in milk and cheese. Nutr Rev, 1997 Feb, 55(2), 57 - 60 Food poisoning, listeriosis, and febrile gastroenteritis; Abscess formation in Listeria monocytogenes-infected gamma delta T cell deficient mouse mutants involves alpha beta T cells; Department of Immunology, University of Ulm, GermanyAlthough mutant mice lacking gamma delta T cells resolve Listeria monocytogenes infection, extensive abscesses are formed . Manifestation of these inflammatory lesions is prevented by in vivo depletion with monoclonal antibodies of CD4, CD8 or both T cell subsets . We conclude that these inflammatory tissue reactions develop when alpha beta T cells of either CD4 or CD8 phenotype are released from control by gamma delta T cells. Microb Pathog, 1997 Feb, 22(2), 79 - 88 Involvement of inflammatory cytokines and nitric oxide in the expression of non-specific resistance to Listeria monocytogenes in mice induced by viable but not killed Mycobacterium bovis BCG; Yang J et al.; The non-specific defense against Listeria monocytogenes could be induced by viable BCG but not by killed BCG in mice . In order to understand the mechanism of antilisterial activity, viable and killed BCG were compared for their ability of inducing cytokine gene expression in spleen cells . Both viable and killed BCG induced the same level of mRNA expression of interleukin 10 (IL-10), transforming growth factor beta (TGF-beta), IL-12 and tumor necrosis factor alpha (TNF-alpha) . Gene expression and production of IL-1 alpha and gamma interferon (IFN-gamma) could be induced by stimulation only with viable BCG . Viable BCG but not killed BCG induced the mRNA expression of inducible nitric oxide synthase (iNOS) . Treatment of mice with NG-monomethyl-L-arginine acetate (NMMA) significantly impaired the non-specific antilisterial action induced by viable BCG . These results demonstrated that NO is an important mediator for the non-specific antilisterial activity induced by viable BCG, and IFN-gamma, IL-1 alpha and TNF-alpha may play a critical role in the non-specific antilisterial activity. Microb Pathog, 1997 Feb, 22(2), 67 - 78 Mutants in the CtpA copper transporting P-type ATPase reduce virulence of Listeria monocytogenes; Francis MS et al.; The CtpA protein from pathogenic Listeria monocytogenes, is a P-type adenosine triphosphatase involved in copper homeostasis . To establish a role in pathogenicity for CtpA, a mutant strain was constructed by insertion of an antibiotic resistance cartridge into the ctpA gene . This mutant was then compared to the wild-type in tissue culture invasion assays and mouse infection studies . Mutants in CtpA, were unaltered for intracellular growth in J774 and HeLa cell lines . However, recovery of mutants from tissue of infected mice was dramatically reduced compared with the wild-type, and a significant impairment in terms of in vivo persistence in mixed-infection competition experiments was observed . These results demonstrate the significance of CtpA in establishing an in vivo infection by L . monocytogenes, and highlight some inadequacies of in vitro tissue culture monolayer assays for determining invasion and intracellular growth of a pathogen. Can J Neurol Sci, 1997 Feb, 24(1), 70 - 2 Musical auditory hallucinosis from Listeria rhombencephalitis; Douen AG et al.; BACKGROUND: Complex auditory hallucinations have rarely been reported in cases of brainstem stroke or tumor . METHOD: Case study . RESULTS: A patient with acute Listeria rhombencephalitis complained of formed musical auditory hallucinations on the side of recent sensorineural deafness . MRI revealed an abscess in the middle cerebellar peduncule with extensive surrounding edema . CONCLUSIONS: Disruption of brainstem auditory pathways may cause complex auditory hallucinations . Potential pathogenetic mechanisms are discussed and a diagnostic approach is proposed. Curr Opin Immunol, 1997 Feb, 9(1), 35 - 43 Inter-relationship among macrophages, natural killer cells and neutrophils in early stages of Listeria resistance; Unanue ER; Reports in the past few years have shown the involvement of different cells and cytokines in controlling the infection with the intracellular facultative pathogen Listeria monocytogenes . A synergistic interaction of T-cell-independent and -dependent processes takes place but the nature of these interactions and of the relevant cells and cytokines depends on both the stage of the infection and the tissue that is involved. Int J Food Microbiol, 1997 Feb, 34(2), 171 - 7 Temperature distribution and prevalence of Listeria spp . in domestic, retail and industrial refrigerators in Greece; Sergelidis D et al.; The present paper examined the presence of Listeria spp . in the environment of domestic, retail and industrial refrigerators . From 136 household refrigerators, 136 surface samples were taken from the walls or shelves, and 125 from cheese compartments . Only two refrigerators harboured L . monocytogenes . From 228 food store refrigerators, 335 samples were taken . Of these, 118 were in in contact with cheeses, 69 with sausages, 21 with cheese and sausages, 20 with miscellaneous products and 107 from refrigerator handles . Listeria spp . and L . monocytogenes were found in 3.1% and 1.7%, of the samples respectively . Listeria spp . was not detected in any of the nine dairy plant refrigerators examined . Listeria monocytogenes and L . innocua were found in 4.5 and 36.4%, respectively, of the 22 refrigerators inside meat processing plants, with only one of 22 refrigerators handles being positive for L . monocytogenes . Temperature distribution in the refrigerators was also investigated . Fifty five per cent of the 136 domestic and 32% of the 228 retail store refrigerators had temperatures of greater than or equal to 9 degrees C . The range of refrigeration temperatures of the industrial refrigerators was 0-2 degrees C for meat plants and 2-7 degrees C for dairy plants . No correlation of any kind could be established between the prevalence of Listeria spp . and the temperature of the various refrigerators due to the low number of positive samples. FEMS Microbiol Lett, 1997 Feb 1, 147(1), 45 - 50 Effect of sampling procedure and strain variation in Listeria monocytogenes on the discrimination of species in the genus Listeria by Fourier transform infrared spectroscopy and canonical variates analysis; Lefier D et al.; The ability to discriminate successfully among cultures of all species of the Listeria genus by infrared spectroscopy in combination with canonical variate analysis was confirmed . The robustness of the method was demonstrated by showing that the separation of L . monocytogenes and L . grayi was hardly affected by variations in broth medium, incubation temperature, incubation time and cell washing procedure . Discrimination among 24 strains of L . monocytogenes according to serotype allowed two groups to be recognised, one comprising serotypes 4 and 4b and the other containing serotypes 1, 1/2b and 1/2c . When strain variation was included in the species discrimination model, the classification of all the L . monocytogenes strains was virtually 100% correct. Appl Environ Microbiol, 1997 Feb, 63(2), 543 - 6 Listeria monocytogenes Scott A transports glucose by high-affinity and low-affinity glucose transport systems; Parker C et al.; Listeria monocytogenes transported glucose by a high-affinity phosphoenolpyruvate-dependent phosphotransferase system and a low-affinity proton motive force-mediated system . The low-affinity system (Km = 2.9 mM) was inhibited by 2-deoxyglucose and 6-deoxyglucose, whereas the high-affinity system (Km = 0.11 mM) was inhibited by 2-deoxyglucose and mannose but not 6-deoxyglucose . Cells and vesicles artificially energized with valinomycin transported glucose or 2-deoxyglucose at rates greater than those of de-energized cells, indicating that a membrane potential could drive uptake by the low-affinity system. Appl Environ Microbiol, 1997 Feb, 63(2), 524 - 31 Functional characterization of pediocin PA-1 binding to liposomes in the absence of a protein receptor and its relationship to a predicted tertiary structure; Chen Y et al.; The physicochemical interaction of pediocin PA-1 with target membranes was characterized using lipid vesicles made from the total lipids extracted from Listeria monocytogenes . Pediocin PA-1 caused the time- and concentration-dependent release of entrapped carboxyfluorescein (CF) from the vesicles . The pediocin-induced CF efflux rates were higher under acidic conditions than under neutral and alkaline conditions and were dependent on both pediocin and lipid concentrations . A binding isotherm constructed on the basis of the Langmuir isotherm gave an apparent binding constant of 1.4 x 10(7) M-1 at pH 6.0 . The imposition of a transmembrane potential (inside negative) increased the CF efflux rate by 88% . Pediocin PA-1 also permeablized synthetic vesicles composed only of phosphatidylcholine . Sequence alignments and secondary-structure predictions for the N terminus of pediocin PA-1 and other class IIa bacteriocins predicted that pediocin PA-1 contained two beta-sheets maintained in a hairpin conformation stabilized by a disulfide bridge . The structural model also revealed patches of positively charged residues, consistent with the argument that electrostatic interactions play an important role in the binding of pediocin PA-1 to the lipid vesicles . This study demonstrates that pediocin PA-1 can function in the absence of a protein receptor and provides a structural model consistent with these results. Curr Opin Cell Biol, 1997 Feb, 9(1), 54 - 61 Actin dynamics in vivo; Welch MD et al.; Actin dynamics in lamellipodia are driven by continuous cycles of actin polymerization, retrograde flow, and depolymerization . In the past year, advances have been made in identifying signaling pathways that regulate actin-filament uncapping and polymerization, in determining the role of myosin motor proteins in retrograde flow, and in evaluating the role of severing proteins in actin depolymerization . Both Listeria monocytogenes and Saccharomyces cerevisiae have emerged as powerful model organisms for studying actin dynamics in cells. Ned Tijdschr Geneeskd, 1997 Jan 25, 141(4), 202 - 4 {Green amniotic fluid as initial symptom of high intestinal obstruction in infants}; Swarte RM et al.; At the birth of two children the amniotic fluid was green colored . The Apgar scores were good . Because of bilious vomiting and food retention, respectively, an open stomach tube was inserted, out of which bilious stomach contains were drained . The cause of green amniotic fluid was not meconium production or infection with Listeria monocytogenes, but mixing with green bile . At further investigation the children both proved to have a high intestinal obstruction distal of the papilla duodeni major. Nature, 1997 Jan 16, 385(6613), 265 - 9 Actin polymerization is induced by Arp2/3 protein complex at the surface of Listeria monocytogenes; Welch MD et al.; The pathogenic bacterium Listeria monocytogenes is capable of directed movement within the cytoplasm of infected host cells . Propulsion is thought to be driven by actin polymerization at the bacterial cell surface, and moving bacteria leave in their wake a tail of actin filaments . Determining the mechanism by which L . monocytogenes polymerizes actin may aid the understanding of how actin polymerization is controlled in the cell . Actin assembly by L . monocytogenes requires the bacterial surface protein ActA and protein components present in host cell cytoplasm . We have purified an eight-polypeptide complex that possesses the properties of the host-cell actin polymerization factor . The pure complex is sufficient to initiate ActA-dependent actin polymerization at the surface of L . monocytogenes, and is required to mediate actin tail formation and motility . Two subunits of this protein complex are actin-related proteins (ARPs) belonging to the Arp2 and Arp3 subfamilies . The Arp3 subunit localizes to the surface of stationary bacteria and the tails of motile bacteria in tissue culture cells infected with L . monocytogenes; this is consistent with a role for the complex in promoting actin assembly in vivo . The activity and subunit composition of the Arp2/3 complex suggests that it forms a template that nucleates actin polymerization. FEMS Microbiol Lett, 1997 Jan 15, 146(2), 303 - 10 Complementation of Listeria seeligeri with the plcA-prfA genes from L . monocytogenes activates transcription of seeligerolysin and leads to bacterial escape from the phagosome of infected mammalian cells; Karunasagar I et al.; Infection experiments have shown that the avirulent species Listeria seeligeri invaded the enterocyte-like cell line Caco-2 with low efficiency but was unable to escape from the phagosome . Introduction of the listeriolysin gene (hly) from L . monocytogenes into L . seeligeri via a recombinant plasmid did not change these characteristics . No measurable transcription of this gene or of the structurally intact chromosomal seeligerolysin gene (lso) was detected . Transformation with a plasmid carrying the bicistronically transcribed plcA-prfA genes from L . monocytogenes resulted in the efficient expression of the plasmid-encoded transcription activator PrfA, a readily detectable synthesis of seeligerolysin and the escape of the bacteria from the phagosome of infected mammalian cells, followed by intracytoplasmic multiplication. N Engl J Med, 1997 Jan 9, 336(2), 100 - 5 An outbreak of gastroenteritis and fever due to Listeria monocytogenes in milk; Dalton CB et al.; BACKGROUND: After an outbreak of gastroenteritis and fever among persons who attended a picnic in Illinois, chocolate milk served at the picnic was found to be contaminated with Listeria monocytogenes . METHODS: In investigating this outbreak, we interviewed the people who attended the picnic about what they ate and their symptoms . Surveillance for invasive listeriosis was initiated in the states that receive milk from the implicated dairy . Stool and milk samples were cultured for L . monocytogenes . Serum samples were tested for IgG antibody to listeriolysin O . RESULTS: Forty-five persons had symptoms that met the case definition for illness due to L . monocytogenes, and cultures of stool from 11 persons yielded the organism . Illness in the week after the picnic was associated with the consumption of chocolate milk . The most common symptoms were diarrhea (present in 79 percent of the cases) and fever (72 percent) . Four persons were hospitalized . The median incubation period for infection was 20 hours (range, 9 to 32), and persons who became ill had elevated levels of antibody to listeriolysin O . Isolates from stool specimens from patients who became ill after the picnic, from sterile sites in three additional patients identified by surveillance, from the implicated chocolate milk, and from a tank drain at the dairy were all serotype 1/2b and were indistinguishable on multilocus enzyme electrophoresis, ribotyping, and DNA macrorestriction analysis . CONCLUSIONS: L . monocytogenes is a cause of gastroenteritis with fever, and sporadic cases of invasive listeriosis may be due to unrecognized outbreaks caused by contaminated food. World Health Stat Q, 1997, 50(1-2), 67 - 73 Foodborne listeriosis; Rocourt J et al.; Various epidemiological investigations of outbreaks and sporadic cases have clearly demonstrated that the consumption of contaminated food is responsible for a high proportion of listeriosis cases and Listeria monocytogenes has been increasingly recognized as an important foodborne pathogen over the last 15 years . The emergence of listeriosis is the result of complex interactions of different factors: medical progress which increases the lifespan and allows immunodeficient people to survive, expansion of the food industry and cold storage systems as well as changes in food habits . None of these factors on its own is entirely responsible . Considerable research has attempted to characterize the organism, define the magnitude of the public health problem and its impact on the food industry, identify the risk factors associated with the disease, and devise appropriate control strategies . Nevertheless, a number of crucial questions remains incompletely elucidated (extent of the foodborne transmission of listeriosis, health status of apparently "healthy patients" with the possible role of an intercurrent infection or genetic susceptibility, how to distinguish highly virulent from less virulent strains of L . monocytogenes, factors contributing to the emergence of outbreaks, the possible role of healthy carriers in the epidemiology of listeriosis, etc.) . To investigate the complexity of listeriosis requires the close collaboration of clinicians, epidemiologists, clinical and food microbiologists, food scientists and the food industry . A large amount of data has been accumulated during the past 10 years but more research is required to elucidate the epidemiology of the disease and the virulence of the causative agent. Scand J Infect Dis, 1997, 29(3), 308 - 9 Fatal Listeria meningitis, endocarditis and pericarditis in a patient with haemochromatosis; Manso C et al.; A 65-year-old man with primary haemochromatosis was admitted because of fever and confusion . He was found to have bacteraemia and meningitis due to Listeria monocytogenes . Treatment with ampicillin plus tobramycin was instituted, and despite an initial improvement, the patient experienced an unfavourable course and died . At postmortem examination, tricuspid valve endocarditis and purulent pericarditis with tamponade were detected . Listeria monocytogenes grew in the culture of the pericardial fluid . Documentation of Listeria monocytogenes pericarditis is extremely rare, and data on the patient described and on seven published cases are reported. Annu Rev Nutr, 1997, 17, 255 - 75 Emerging issues in microbiological food safety; Meng J et al.; Many microorganisms previously unrecognized as food-borne or harmful are emerging as human pathogens transmitted by food . This is a result of recent acquisition of key virulence factors, detection by newly developed isolation procedures, or astute detective-like laboratory skills of microbiologists . Six microbial pathogens, including Shiga toxin-producing Escherichia coli, Listeria monocytogenes, Arcobacter butzleri, Helicobacter pylori, Cryptosporidium parvum, and Cyclospora, have become recognized as significant causes of human illness . Although the ecology and epidemiology of illness caused by some of these pathogens have not been fully elucidated, food has the potential of being an important vehicle in their dissemination . Existing technologies and new approaches such as irradiation and hazard analysis critical control point (HACCP) programs are useful tools in the control of food-borne hazards . However, because of ever-changing products, processes, food-handling practices, societal habits, and pathogens, emerging food-borne diseases will continue to be an important public health concern. J Clin Dent, 1997, 8(2 Spec No), 54 - 61 A comparison of intraoral antimicrobial effects of stabilized stannous fluoride dentifrice, baking soda/peroxide dentifrice, conventional NaF dentifrice and essential oil mouthrinse; Bacca LA et al.; The intraoral antimicrobial activity of four commercial oral products-conventional NaF dentifrice (Crest), baking soda/peroxide/NaF dentifrice (Mentadent), essential oil mouthrinse (Listerine) and SnF2 dentifrice (Crest Plus Gum Care)-have been compared in three test regimens . Formulations were compared for their ability to suppress the regrowth and apical extension of dental plaque following toothbrushing during thirty hours of non-brushing where products were used as oral rinses (30-hour plaque regrowth model) . Formulations were also compared for their ability to suppress the colony-forming units (cfu) of facultative anaerobic bacteria sampled from buccal gingival surfaces following use (Gingival Surface Microbial Index-GSMI model) . Lastly, formulations were compared for effects in suppressing the glycolytic metabolic activity and regrowth activity of in vivo-treated dental plaques sampled at various periods following topical use and incubated under controlled ex vivo conditions (Plaque Glycolysis and Regrowth-PGRM model) . In thirty-hour plaque regrowth testing, the rank ordered antimicrobial efficacy of formulations followed SnF2 > essential oils > NaF = water = baking soda/peroxide . In GSMI testing, all formulations were shown to suppress the cfu of facultative anaerobic bacteria relative to baseline, although SnF2 treatment was observed to reduce bacterial levels to a significantly greater degree than NaF dentifrice or baking soda/peroxide dentifrice up to two hours following brushing . In PGRM testing, the SnF2 dentifrice provided significant inhibition of bacterial metabolism and regrowth following topical application when compared with the NaF dentifrice as control . The baking soda/peroxide dentifrice provided no reduction in either bacterial metabolism or regrowth in PGRM . Previous studies had demonstrated modest effects for essential oil rinse in reducing PGRM plaque regrowth, with no effects for this treatment on plaque metabolism . Overall, these results demonstrate that SnF2 dentifrice provides substantial intraoral antimicrobial effects . The essential oil mouthrinse also exhibits significant intraoral antimicrobial effects, albeit apparently less than SnF2 dentifrice . The baking soda/peroxide dentifrice did not produce any antimicrobial effects following in vivo use compared with conventional dentifrice . These results provide mechanistic rationale for the chemotherapeutic efficacy of SnF2 and essential oil formulations in reducing gingivitis, while providing no support for the expectation of clinical efficacy for formulations containing baking soda and peroxide. J Clin Dent, 1997, 8(2 Spec No), 46 - 53 The comparative efficacy of stabilized stannous fluoride dentifrice, peroxide/baking soda dentifrice and essential oil mouthrinse for the prevention of gingivitis; Beiswanger BB et al.; This double-blind parallel-design clinical study compared the efficacy of a stabilized stannous fluoride dentifrice (Crest Plus Gum Care), baking soda and peroxide (NaF) dentifrice (Mentadent), and essential oil mouthrinse (Listerine) to a conventional NaF dentifrice (Crest) for the control of plaque, gingivitis and gingival bleeding over six months . Following an initial baseline examination and stratification, subjects received a complete oral prophylaxis and were distributed assigned test products . Following three and six months, subjects re-visited the clinic for examinations . Evaluations at baseline and at 3 and 6 months included soft tissue status . Loe-Silness gingivitis/gingival bleeding, Silness-Loe plaque and dental stain . Results subsequent to six months of product use were as follows: At six months, the stabilized stannous fluoride dentifrice was observed to produce statistically significant 17.5% reductions in gingivitis and 27.5% reductions in gingival bleeding relative to the NaF dentifrice . The combination of sodium fluoride dentifrice and essential oil mouthrinse produced statistically significant reductions of 7.4% in gingivitis and 10.8% in plaque as compared with the NaF dentifrice . The stabilized stannous fluoride dentifrice produced statistically significant reductions in both gingivitis (10.8%) and gingival bleeding (23.0%) relative to the combination of sodium fluoride dentifrice and essential oil mouthrinse . The baking soda and peroxide (NaF) dentifrice did not provide reductions in gingivitis, plaque or gingival bleeding as compared with the conventional NaF dentifrice . The stabilized stannous fluoride dentifrice provided statistically significant reductions in gingivitis as compared with the baking soda and peroxide dentifrice following six months of use, and both the essential oil mouthrinse and stabilized stannous fluoride dentifrice provided statistically significant reductions in gingivitis as compared with the baking soda and peroxide dentifrice following three months of use . These results support: 1) the efficacy of stabilized stannous fluoride dentifrice and the combination of sodium fluoride dentifrice and essential oil mouthrinse for the prevention of gingivitis; 2) the superior activity of stabilized stannous fluoride dentifrice as compared with a combination of sodium fluoride dentifrice and essential oil mouthrinse for the control of gingivitis and gingival bleeding; and 3) the lack of efficacy for baking soda and peroxide dentifrice for the control of plaque, gingivitis and gingival bleeding as compared with conventional fluoridated dentifrice. Anim Reprod Sci, 1997 Jan, 45(4), 311 - 27 Effect of experimental infection with Listeria monocytogenes on the development of pregnancy and on concentrations of progesterone, oestrone sulphate and 15-ketodihydro-PGF2 alpha in the goat; Engeland IV et al.; The effect of Listeria monocytogenes infection on hormone levels in pregnant goats was studied . Four goats (Group I) received an intravenous inoculation of a bacterial culture (Type 1) on Days 69-77 and another four goats (Group II) received a similar inoculation on Days 105-106 of gestation . Five non-inoculated goats were used as controls . Plasma was analysed for progesterone, oestrone sulphate and 15-ketodihydro-PGF2 alpha . The status of the foetus was followed using real-time ultrasonography . Three of the four goats in Group I aborted 8-10 days after inoculation . The fourth goat gave birth to a normal live kid at term . The three goats which aborted showed clinical signs of disease in connection with abortion . In Group II, all goats aborted after 9-11 days . All the goats showed clinical symptoms of disease from a few days after inoculation and the symptoms continued until abortion . The clinical symptoms of disease were more pronounced in Group II than in Group I . L . monocytogenes was isolated from all aborted foetuses . None of the control goats aborted . Ultrasound examination revealed foetal death either immediately before or up to 2 days before abortion . Mummification had begun in the foetus that had been dead for 2 days before expulsion . In comparison with pre-inoculation plasma levels in Group I, a significant decrease (P < 0.05) in progesterone levels and an increase in 15-ketodihydro-PGF2 alpha levels were observed from Days 4 and 6 after inoculation, respectively . In Group II, a significant decrease (P < 0.05) in progesterone levels and an increase in 15-ketodihydro-PGF2 alpha levels in plasma were observed from Days 8 and 6, respectively . The oestrone sulphate levels decreased slightly in the inoculated goats a few days before abortion . The pattern of changes in levels around abortion was similar to the pattern present in the control animals around parturition . However, oestrone sulphate levels did not increase in the inoculated groups before abortion in contrast to goats which delivered healthy kids . The changes in levels of 15-ketodihydro-PGF2 alpha in goats that aborted indicated that the endocrine foetal-placental function was disturbed, which was most likely due to the establishment and development of L . monocytogenes in the placenta and foetus. Crit Rev Microbiol, 1997, 23(2), 77 - 107 Antibodies to Listeria monocytogenes; Bhunia AK; Listeria monocytogenes is one of the leading foodborne pathogens and has been implicated in numerous outbreaks in the last 2 decades . Immunocompromised populations are usually the most susceptible to Listeria infections . Although the pathogenic mechanism is a complex process, significant progress has been made in unravelling the mechanism in recent years . It is now clear that numerous extracellular and cell-associated proteins, such as internalin, listeriolysin, actin polymerization protein, phospholipase, metalloprotease, and possibly p60 proteins, are essential for L . monocytogenes entry into mammalian cells, survival inside the phagosome, escape into the cytoplasm, and cell-to-cell spread . Other proteins may be responsible for growth and physiology or to maintain the structural integrity of the bacteria . Monoclonal and polyclonal antibodies have been developed against many of those antigens or their synthetic derivatives that have helped greatly to determine the structure and function of these antigens . The antibodies were also used for the diagnosis and detection, immunocytochemical staining, and serotyping of Listeria . Humoral immune response to live L . monocytogenes cells was examined in naturally or experimentally infected hosts . Studies revealed that only extracellular antigens induced the humoral response, whereas cell-associated antigens had apparently no response . It is speculated that during the occasional bacteremic phase, L . monocytogenes releases extracellular antigens that are then processed by the immune system for antibody production . As L . monocytogenes is an intracellular pathogen, the cell-associated antigens are not persistent in the blood circulation and thus fail to stimulate the humoral immune response. Stomatologiia (Mosk), 1997, 76(2), 26 - 7 {The comparative characteristics of the antibacterial activity of new antiseptics and the prospects for their use in dental practice}; Dmitrieva LA et al.; Antibacterial activities of modern antiseptics listerine, myramistine, cidipol, octenisept, tantum verde, matecide, and rautine drugs chlorhexidine and dioxidine are compared . The prospects of their use in dentistry for the treatment of inflammations associated with anaerobes are discussed . Metacide, listerine, chlorhexidine, and dioxidine are characterized by the widest spectrum of activity towards obligate anaerobic bacteria; moreover, these drugs inhibit bacterial growth when used in lower concentrations than other drugs. Folia Microbiol (Praha), 1997, 42(1), 65 - 71 Primary Listeria monocytogenes infection in gestating mice; Abram M et al.; The facultative intracellular Gram-positive bacterium Listeria monocytogenes is a food-borne pathogen of frequently underestimated importance . Pregnant women represent the high-risk group for L . monocytogenes infection . Abortion, stillbirth or neonatal infection can be the serious outcome of such an infection . Recovery from listeriosis, resistance mechanisms of the host and the effect of L . monocytogenes on fetal development still remain to be fully understood . The results of our experiments showed an increased susceptibility of gestating BALB/c mice to primary L . monocytogenes infection . The duration of listeriosis in gestating animals was almost twice longer than in the control group . Furthermore, it was clearly shown that the detrimental effect of L . monocytogenes on fetal development was more pronounced if the infection was acquired earlier during gestation. Leuk Lymphoma, 1997 Jan, 24(3-4), 335 - 9 2-Chlorodeoxyadenosine as initial therapy for advanced low grade lymphomas; Canfield VA et al.; In order to evaluate efficacy and safety of 2-chlorodeoxyadenosine (2-CdA) as primary therapy of low grade non Hodgkin's lymphoma, a phase II trial of 2-CdA was initiated in patients with previously untreated advanced low grade lymphoma . Fourteen previously untreated patients with stage III and IV low grade lymphoma were enrolled . Patients received 2-CdA 0.1 mg/kg/d by continuous infusion for 7 days every 28 days, for 1-6 cycles of therapy (median 3.5) . Results showed one complete response and nine partial responses for an overall response rate of 75% . Until now there have only been three responding patients who have had progressive disease, with a median follow-up time of 18 months . The major toxicity was bone marrow suppression and nine patients stopped therapy prior to a planned six cycles because of prolonged cytopenias, primarily thrombocytopenia . Fifteen of 50 cycles of therapy were associated with neutropenic febrile episodes and there was one septic death secondary to Listeriosis . It seems from this small group of patients that 2-CdA is an active agent in previously untreated low grade lymphoma . Myelosuppression is cumulative and limits the number of cycles of therapy which can be given . Future exploration of different doses or schedules of this active agent is warranted. Vet J, 1997 Jan, 153(1), 9 - 29 A review of Listeria monocytogenes and listeriosis; Low JC et al.; Following the initial isolation and description in 1926 Listeria monocytogenes has been shown to be of world-wide prevalence and is associated with serious disease in a wide variety of animals, including man . Our knowledge of this bacterial pathogen and the various forms of listeriosis that it causes has until recently been extremely limited, but recent advances in taxonomy, isolation methods, bacterial typing, molecular biology and cell biology have extended our knowledge . It is an exquisitely adaptable environmental bacterium capable of existing both as an animal pathogen and plant saprophyte with a powerful array of regulated virulence factors . Most cases of listeriosis arise from the ingestion of contaminated food and in the UK the disease is particularly common in ruminants fed on silage . Although a number of forms of listeriosis are easily recognized, such as encephalitis, abortion and septicaemia, the epidemiological aspects and pathogenesis of infection in ruminants remain poorly understood . The invasion of peripheral nerve cells and rapid entry into the brain is postulated as a unique characteristic of its virulence, but relevant and practical disease models are still required to investigate this phenomenon . This review offers an up to date introduction to the organism with a description of virulence determinants, typing systems and a detailed account of listeriosis in animals . Experimental and field papers are reviewed and further sections deal with the diagnosis, treatment and control of listeriosis in animals . A final part gives an overview of listeriosis in man. J Dairy Sci, 1997 Jan, 80(1), 220 - 9 Molecular diagnostics for dairy-borne pathogens; Batt CA; Advances in diagnostic assays based on nucleic acids will revolutionize the ability of the industry to maintain the safety of dairy foods . Two complementary assay formats are explored, one of which permits the rapid detection of bacterial pathogens and the other the identification of reservoirs of these pathogens . The first format is an assay based on the polymerase chain reaction that employs homogeneous detection (TaqMan polymerase chain reaction detection; Perkin Elmer, Applied Biosystems Division, Foster City, CA) of the target sequence . This assay has been applied to the detection of Listeria monocytogenes . A primary problem with current assays that are based on polymerase chain reaction is the complexity of sample handling and the quantification of the initial target number . This fluorogenic assay takes advantage of the endogenous 5',3'-endonuclease activity in Taq DNA polymerase . Approximately 100 samples can be analyzed in 2 to 3 h with a sensitivity of < 50 cells and a dynamic range of > 1000-fold . The TaqMan polymerase chain reaction detection assay is a robust format that is readily applicable to a wide array of other pathogens found in foods and in the environment . The second format is an instrument for automated ribosomal RNA analysis (Riboprinter; DuPont, Wilmington, DE) that can be used to locate the reservoirs harboring the bacterial pathogen . Use of this typing method it has been shown that, although a number of different ribotypes can be isolated from a single environmental sample, only a selected number of these strains apparently have the ability to cause disease . The future of food microbiology lies in the development and integration of molecular methods that can be automated into a testing regimen that extends from the farm to finished products. J Appl Microbiol, 1997 Jan, 82(1), 32 - 8 Nisin induces changes in membrane fatty acid composition of Listeria monocytogenes nisin-resistant strains at 10 degrees C and 30 degrees C; Mazzotta AS et al.; Listeria monocytogenes isolates resistant to 10(5) IU ml-1 nisin were obtained at 30 degrees C (NR30) and at 10 degrees C (NR10) . Nisin prolonged the lag phase of isolate NR30 at 10 degrees C . Isolates NR30 and NR10 did not produce a nisinase . Protoplasts of isolate NR30 were unaffected by exposure to nisin . The fatty acid composition from the wild-type strain and NR isolates was determined . As expected, temperature-induced differences in the C15/C17 fatty acid ratios were found . Growth of the NR strains in the presence of nisin resulted in significantly different C15/C17 ratios and a significant increase in the percentage of C16:0, C16: 1, C18:0 and C18: 1 fatty acids at 10 degrees C and 30 degrees C . Both the NR10 and NR30 isolates had similar growth rates at low temperatures, but these were slower than the wild-type strain . These results indicate that 'nisin resistance' is an environmentally defined phenotype and that nisin induces changes in the fatty acid composition of the membrane in L . monocytogenes nisin-resistant isolates regardless of the growth temperature. Arch Immunol Ther Exp (Warsz), 1997, 45(1), 49 - 54 Interleukin 12 and direct cytotoxicity of spleen lymphocytes to Listeria innocua-phagocyting syngeneic macrophages in C57BL/6 and BALB/c mice; Szeliga J et al.; Production of interleukin 12 (IL-12) during cytotoxic reaction of C57BL/6 and BALB/c spleen lymphocytes or their subpopulations: T+B, T, CD4+ and CD8+ cells to L . innocua-phagocyting syngeneic macrophages was examined . The effector cell donors were untreated or L . innocua-infected . The number of surviving bacteria in phagocytes was tested and IL-12 level in culture supernatants of reacting cells was determined . C57BL/6 mice, resistant to Listeria infection, were found to develop stronger cell cytotoxicity to bacteria-phagocyting syngeneic macrophages than BALB/c mice . The lymphocytes responsible for that phenomenon were of CD8+ phenotype . IL-12 was produced only during nonspecific cytotoxic reaction of CD4+ and CD8+ T cells . It is suggested that the innate resistance of mice to Listeria is dependent on their ability to develop a specific cytotoxic reaction and IL-12 production. J Cell Sci, 1997 Jan, 110 ( Pt 2), 191 - 200 Transfer of phagocytosed particles to the parasitophorous vacuole of Leishmania mexicana is a transient phenomenon preceding the acquisition of annexin I by the phagosome; Collins HL et al.; The eukaryotic intracellular pathogen Leishmania mexicana resides inside macrophages contained within a membrane bound parasitophorous vacuole which, as it matures, acquires the characteristics of a late endosomal compartment . This study reports the selectivity of fusion of this compartment with other particle containing vacuoles . Phagosomes containing zymosan or live Listeria monocytogenes rapidly fused with L . mexicana parasitophorous vacuoles, while those containing latex beads or heat killed L . monocytogenes failed to do so . Fusigenicity of phagosomes was not primarily dependent on the receptor utilized for ingestion, as opsonization with defined ligands could not overcome the exclusion of either latex beads or heat killed organisms . However modulation of intracellular pH by pharmacological agents such as chloroquine and ammonium chloride increased delivery of live Listeria and also induced transfer of previously excluded particles . The absence of fusion correlated with the acquisition of annexin I, a putative lysosomal targeting, molecule, on the phagosome membrane . We propose that the acquisition of cellular membrane constituents such as annexin I during phagosome maturation can ultimately direct the fusion pathway of the vesicles formed and have described a model system to further document changes in vesicle fusigenicity within cells. Int Immunol, 1997 Jan, 9(1), 105 - 15 Active catabolism of glucocorticoids by 11 beta-hydroxysteroid dehydrogenase in vivo is a necessary requirement for natural resistance to infection with Listeria monocytogenes; Hennebold JD et al.; The results from the present study demonstrate that the innate defense mechanisms which control the progressive growth of Listeria monocytogenes in normal animals in vivo are dependent upon the active catabolism of endogenous glucocorticoids by the enzyme 11 beta-hydroxysteroid dehydrogenase (11 beta-HSD) . When 11 beta-HSD activity was pharmacologically inhibited in vivo, host susceptibility to progressive bacterial disease was markedly increased . Depressed natural resistance following 11 beta-HSD inhibition correlated with changes in the patterns of inducible cytokines by macrophages and T cells . Similar changes were observed when normal adult animals were treated with low doses of dexamethasone prior to experimental infection with Listeria. Immunopharmacology, 1997 Jan, 35(3), 273 - 82 Effect of hot water extract of Chlorella vulgaris on cytokine expression patterns in mice with murine acquired immunodeficiency syndrome after infection with Listeria monocytogenes; Hasegawa T et al.; We have previously reported that oral administration of hot water extract of Chlorella vulgaris (CVE) enhances resistance to Listeria monocytogenes through augmentation of Listeria-specific cell-mediated immunity in normal mice and mice with murine acquired immunodeficiency syndrome (MAIDS) caused by murine leukemia virus (MuLV) LP-BM5 . To elucidate the mechanisms whereby CVE augments the cell-mediated immunity, we examined the expression patterns of mRNA for cytokines in normal and MAIDS mice given CVE orally after L . monocytogenes infection . The expression levels of IL-1 alpha, IL-12, GM-CSF, MIP and TNF alpha genes were significantly augmented in the peritoneal adherent cells by oral administration of CVE for 2 weeks before Listeria infection . The expression levels of gamma IFN and IL-12 mRNA were significantly higher in the spleen after Listeria infection in CVE-treated mice than in normal mice, while the expression of IL-10 mRNA in the spleen was decreased by CVE administration . In MAIDS mice, oral administration of CVE also augmented the expression of gamma IFN and IL-12 mRNA in the spleen after Listeria infection, while it rather reduced the expression of IL-10 mRNA . These results suggest that CVE may preferentially augment THI responses against Listeria via activation of macrophages to produce IL-12 and enhance host defence against Listeria infection both in normal and MAIDS mice. Life Sci, 1997, 60(8), 545 - 54 Effect of dietary flaxseed on fatty acid composition, superoxide, nitric oxide generation and antilisterial activity of peritoneal macrophages from female Sprague-Dawley rats; Babu US et al.; The impact of ground flaxseed (FS) or flaxseed meal (FSM) diets on the fatty acid composition and functions of rat peritoneal exudate cells (PEC) was determined . Female weanling Sprague-Dawley rats (10/group) were fed isocaloric AIN-76 diets supplemented with 0.0, 10.0% (w/w) FS or 6.2% (w/w) FSM . At the end of 56-days, rat serum and thioglycollate-elicited PEC were analyzed for total lipid fatty acids . Production of nitric oxide (NO) and superoxide (O2-), Listeria monocytogenes (LM) phagocytic index and antilisterial activity of resident PEC were also assessed . A significant increase in alpha-linolenic (C18:3), eicosapentanoic (C20:5) and docosahexanoic (C22:6) acids, as well as a significant reduction in arachidonic acid (C20:4) was observed in the serum of rats fed 10% FS . Dietary FS caused a significant reduction in palmitic acid (C16:0) and an increase in stearic acid (C18:0) of PEC . Defatted FSM produced a significant increase in long chain fatty acids, which included eicosadienoic acid (C20:2) in PEC and C22:6 in serum . PEC from rats fed 10.0% FS produced significantly less (about 50%) O2- in response to phorbol myristate acetate (PMA), than did PEC from control animals; dietary treatment had no effect on O2- in response to LM . FSM had no impact on the O2- production by PEC in response to PMA or LM . Antilisterial activity of PEC was determined by comparing bacterial uptake after 1 hr with recovery 24 hrs later . Despite comparably equivalent bacterial uptake, few viable intracellular LM were recovered at T = 24 for all test samples, indicating that, regardless of the dietary treatment, PEC were able to handle the in vitro LM infection . This bacterial clearance was accompanied by equivalent NO generation by PEC from each dietary group in response to LM . Summarily, dietary FS produced significant changes in fatty acid composition of serum and PEC, inhibited O2- generation by PEC, and was ineffectual to both NO production by and antilisterial activity of PEC. Clin Sci (Lond), 1997 Jan, 92(1), 95 - 101 Dietary fish oil reduces survival and impairs bacterial clearance in C3H/Hen mice challenged with Listeria monocytogenes; Fritsche KL et al.; 1 . To investigate the effect of dietary fat source on host resistance to intracellular pathogens, weanling female C3H/Hen mice were fed one of three experimental diets containing, 20% by weight, lard, soybean oil or 17% menhaden fish oil plus 3% corn oil . After 4 weeks, survival of mice (n = 12/treatment group) injected intraperitoneally with 2 x 10(6) colony forming units of live Listeria monocytogenes was determined . In a second study, bacterial clearance from the liver and spleen at 2, 4 and 7 days post-challenge was determined (n = 8/treatment group) . 2 . We found that the survival of mice fed the diets with soybean oil or menhaden fish oil was significantly lower than those fed lard (P < 0.05) . Survival rates were 58% (7/12), 33% (4/12) and 100% (12/12), respectively, for mice fed soybean oil, menhaden fish oil and lard . In the second study, mice fed menhaden fish oil had approximately 1 log10 greater bacteria in their spleens at day 4 than mice fed lard or soybean oil (P < 0.001) . There were no significant treatment differences in the number of bacteria recovered from liver samples . 3 . In summary, dietary fat source significantly affects murine resistance to Listeria, with diets rich in n-3 polyunsaturated fatty acids, such as from fish oil, having the most detrimental effect. Lett Appl Microbiol, 1997 Jan, 24(1), 65 - 8 A case of foodborne listeriosis in Sweden; Loncarevic S et al.; A 70-year-old woman fell seriously ill overnight with meningitis and was admitted to hospital . Cerebrospinal fluid culture yielded Listeria monocytogenes . One of the first problems in solving a human case of listeriosis suspected to be foodborne is to find the foods likely to have been transmitting L . monocytogenes . Two enrichment procedures and a direct plating procedure were used for isolation of the bacteria from different food items collected from the patient's refrigerator, local retail store and producer . Samples of vacuum-packed products of sliced pork brawn, sliced cooked medwurst and berliner wurst of the same brand harboured L . monocytogenes . Serotyping and restriction enzyme analysis (REA) with pulsed-field gel electrophoresis (PFGE) were used to characterize and compare 41 isolates, including the human strain . At least three clones were present in the foods investigated, and one of these was identical to the human clone . This clone was present in samples of medwurst from the patient's refrigerator and the local retail store . This is, to our knowledge, the first proven foodborne case of listeriosis reported in Sweden. Lett Appl Microbiol, 1997 Jan, 24(1), 51 - 4 Optimization of the detection of bacteriophages induced from Listeria sp; Lemaitre JP et al.; It is necessary to isolate new phages in order to improve the rate of typeability of Listeria monocytogenes strains . We propose a method which increases the detection of induced phages in the presence of inhibitory substances synthesized or liberated by the cells during phage production . Of the 29 phages isolated, 11 (38%) were detected by the spot-on-the-lawn technique and 18 (62%) were revealed by the soft-agar technique . To increase the rate of phage detection, both techniques appear useful . Listeria cultures were subjected to phage typing procedures utilizing these newly isolated phages and the French International set of phages . It appears that the newly isolated phages are good tools for the differentiation of Listeria strains . Among them, one phage seems to be complementary to the French International set. Eur J Haematol, 1997 Jan, 58(1), 46 - 50 2-Chlorodeoxyadenosine in the treatment of relapsed/refractory chronic lymphoproliferative disorders; Rondelli D et al.; 2-Chlorodeoxyadenosine (2-CdA) is a purine analog with cytotoxic activity on both resting and cycling lymphocytes which has been used as salvage therapy in advanced/resistant chronic lymphoproliferative disorders . In our study 39 patients (19 B-CLL, 5 B-PLL, 9 low-grade B-NHL, 5 CTCL and 1 high-grade T-NHL) who relapsed or became resistant after 1-4 chemotherapy regimens were treated with 2-CdA 6 mg/m2 per day by 2 h infusion for 5 d every 28 d . The overall clinical response rate, including complete remission (CR) and partial remission (PR), was 66% . Two of 19 (10%) B-CLL patients achieved a CR lasting 9 months, while 11/19 B-CLL (58%) and 4/5 B-PLL (3 B-PLL/B-CLL and 1 B-PLL) (80%) achieved a PR . Interestingly, 5 of 6 patients who had been previously treated with fludarabine obtained a clinical response (2 CR and 3 PR) . One of 9 (11%) low-grade B-NHL patients achieved a CR and relapsed after 26 months, and 5/9 (55%) achieved a PR . One of 5 (20%) CTCL achieved a CR lasting 32 months, while 2/5 (40%) achieved a PR . The overall mean duration of PR was 7.4 months and no differences were observed among different groups of patients . Toxicity was acceptable, as only a transient severe hematological impairment was observed in 20% of the patients while nonhematological toxicity was not documented . Two patients died because of bacterial pneumonia, 1 of meningitis due to Listeria and 9 from progression of the disease . In conclusion, treatment with 2-CdA in heavily pretreated patients with chronic lymphoproliferative disorders is well tolerated and obtains high response rates, even in patients relapsed after treatment with fludarabine. Antimicrob Agents Chemother, 1997 Jan, 41(1), 60 - 5 Comparative activities of new fluoroquinolones, alone or in combination with amoxicillin, trimethoprim-sulfamethoxazole, or rifampin, against intracellular Listeria monocytogenes; Michelet C et al.; We studied the activities of the new fluoroquinolones clinafloxacin, levofloxacin, ofloxacin, and sparfloxacin alone or in combination on the intracellular growth of Listeria monocytogenes . Against intracellular growth of the four strains tested, a similar reduction of the bacterial count was obtained with clinafloxacin at the dose of 10 x MIC (delta log10 CFU/ml = -2.19 +/- 0.24), with levofloxacin at 8 x MIC (delta log10 CFU/ml = -2.28 +/- 0.25), and with sparfloxacin at 4 x MIC (delta log10 CFU/ml = -2.16 +/- 0.21) after 24 h of incubation . The combination of the quinolones with trimethoprim-sulfamethoxazole or amoxicillin did not show a substantial increase in activity compared to the fluoroquinolone alone . Antagonism with rifampin was strongly suggested . No modification of the MIC was observed after 20 successive infections of HeLa cells and contact with subinhibitory concentrations of clinafloxacin, levofloxacin, and sparfloxacin for 24 h . We conclude that clinafloxacin, levofloxacin, or sparfloxacin could represent a therapeutic alternative to amoxicillin for the treatment of Listeria infections in adults, especially clinafloxacin, whose MIC is low (0.06 to 0.12 micrograms/ml), and whose best activity against intracellular L . monocytogenes was obtained at a concentration of 1.2 micrograms/ml, which is similar to clinically achievable levels . The results must be confirmed in an experimental model. Appl Environ Microbiol, 1997 Jan, 63(1), 310 - 3 A nucleic acid sequence-based amplification system for detection of Listeria monocytogenes hlyA sequences; Blais BW et al.; A nucleic acid sequence-based amplification system primarily targeting mRNA from the Listeria monocytogenes hlyA gene was developed . This system enabled the detection of low numbers (< 10 CFU/g) of L . monocytogenes cells inoculated into a variety of dairy and egg products after 48 h of enrichment in modified listeria enrichment broth. J Immunol, 1997 Jan 1, 158(1), 359 - 66 Antigen-driven but not lipopolysaccharide-driven IL-12 production in macrophages requires triggering of CD40; DeKruyff RH et al.; We demonstrated that two distinct pathways exist for the induction of IL-12 in APC . The first pathway for IL-12 production occurred during responses to T cell-dependent Ags such as OVA and required triggering of CD40 molecules on the APC . IL-12 production in this T cell-dependent system increased in direct proportion to Ag concentration and required TCR ligation but not CD28 costimulation . The second pathway occurred when bacterial products such as LPS or heat-killed Listeria monocytogenes were used to activate macrophages to produce IL-12 in the complete absence of T cells . In this second pathway, IL-12 production was completely independent of CD40 triggering . In both pathways, the presence of IFN-gamma was not required for induction of IL-12 synthesis when splenic adherent cells (SAC) from normal mice were used . However, addition of IFN-gamma to cultures of Th2 T cells and SAC increased IL-12 production two- to fivefold, and addition of rTNF-alpha with IFN-gamma further enhanced IL-12 production . The addition of TNF-alpha in the absence of IFN-gamma, however, had no effect on IL-12 production in the T cell-dependent pathway . Similarly, addition of TNF-alpha in the presence or the absence of IFN-gamma to cultures of LPS or heat-killed Listeria and SAC did not increase IL-12 production, but addition of IFN-gamma alone greatly enhanced IL-12 production, consistent with the idea that bacterial stimuli induce significant quantities of endogenous TNF-alpha production . These results indicate that the requirements for the induction of IL-12 production in T cell-dependent and T cell-independent responses differs mainly with regard to CD40 triggering . Furthermore, these results suggest that IL-12 production can be induced by bacterial products in patients with hyper-IgM syndrome who lack CD40 ligand expression and in those treated with soluble gp39 to interrupt CD40-CD40 ligand interactions. J Immunol, 1997 Jan 1, 158(1), 287 - 93 Immune CD8+ T lymphocytes lyse Listeria monocytogenes-infected hepatocytes by a classical MHC class I-restricted mechanism; Jiang X et al.; Hepatocytes constitute the principal site of listerial replication in the livers of mice infected i.v . CD8+ T lymphocytes play a predominant role in the host defenses to Listeria monocytogenes . In vitro experiments by others undertaken to delineate the functions of CD8+ T lymphocytes have focused primarily on their interaction with Listeria-infected macrophages . Such experiments do not address directly the role of CD8+ T lymphocytes in eliminating the bulk of Listeria replicating within the liver . Here, we report that immune CD8+ T cells at an E:T cell ratio > or = 10:1 lysed Listeria-infected hepatocytes as judged by the following two criteria . Aspartate aminotransferase activity in the culture supernatants, indicative of hepatocyte damage, increased significantly . Conversely, infected hepatocytes cocultured with immune CD8+ T cells exhibited a marked reduction in viable intracellular Listeria assessed by CFUs . Neither immune CD4+ T cells nor nonimmune CD8+ T cells caused a similar increase in aspartate aminotransferase activity released or a decrease in intracellular bacteria . Immune CD8+ T cell-mediated lysis of infected hepatocytes was restricted by classical MHC class I (H-2Kb) molecules and was inhibited by the presence of either brefeldin A or mAb specific for CD8 . These results suggest that the predominant role of CD8+ T lymphocytes in host resistance to listerial infections of the liver may be due to their capacity to lyse infected hepatocytes. Infect Immun, 1997 Jan, 65(1), 101 - 9 Identification and characterization of a novel PrfA-regulated gene in Listeria monocytogenes whose product, IrpA, is highly homologous to internalin proteins, which contain leucine-rich repeats; Domann E et al.; The expression of all virulence factors in Listeria monocytogenes characterized to date is controlled by the virulence regulator protein, PrfA . To identify further PrfA-regulated proteins, we examined supernatants of L . monocytogenes EGD harboring additional copies of the PrfA regulator for the presence of novel proteins . This led to the identification and biochemical purification of a hitherto uncharacterized PrfA-dependent 30-kDa protein (A . Lingnau, T . Chakraborty, K . Niebuhr, E . Domann, and J . Wehland, Infect . Immun . 64:1002-1006, 1996) . Oligonucleotide primers derived from internal peptide sequences of this protein allowed the cloning and determination of the entire sequence of the respective gene . The protein comprised 297 amino acids with strong overall homology to the internalins, InlA and InlB, particularly in the region harboring the leucine-rich repeats . The gene has been designated irpA for internalin-related protein A gene . Transcriptional studies revealed that the gene was monocistronic and, like the inlA and inlB genes, was transcribed by PrfA-dependent and PrfA-independent mechanisms . Monoclonal antibodies raised against IrpA indicated that it was produced by L . monocytogenes but not by the nonpathogenic species Listeria innocua . To examine the role of IrpA in pathogenesis, we constructed an isogenic in-frame deletion mutant that removed all but 116 amino acids of the IrpA protein . This mutant was neither defective for invasion into many tissue culture cell lines nor did it demonstrate reduced intracellular survival . However, in vivo studies using the mouse infection model revealed that the irpA mutant showed reduced virulence compared to the parental strain . These results suggest a role for IrpA during disseminated infection by L . monocytogenes. Infect Immun, 1997 Jan, 65(1), 78 - 88 Host cell heparan sulfate proteoglycans mediate attachment and entry of Listeria monocytogenes, and the listerial surface protein ActA is involved in heparan sulfate receptor recognition; Alvarez-Dominguez C et al.; The mechanisms by which the intracellular pathogen Listeria monocytogenes interacts with the host cell surface remain largely unknown . In this study, we investigated the role of heparan sulfate proteoglycans (HSPG) in listerial infection . Pretreatment of bacteria with heparin or heparan sulfate (HS), but not with other glycosaminoglycans, inhibited attachment and subsequent uptake by IC-21 murine macrophages and CHO epithelial-like cells . Specific removal of HS from target cells with heparinase III significantly impaired listerial adhesion and invasion . Mutant CHO cells deficient in HS synthesis bound and internalized significantly fewer bacteria than wild-type cells did . Pretreatment of target cells with the HS-binding proteins fibronectin and platelet factor 4, or with heparinase III, impaired listerial infectivity only in those cells expressing HS . Moreover, a synthetic peptide corresponding to the HS-binding ligand in Plasmodium falciparum circumsporozoite protein (pepPf1) inhibited listerial attachment to IC-21 and CHO cells . A motif very similar to the HS-binding site of pepPf1 was found in the N-terminal region of ActA, the L . monocytogenes surface protein responsible for actin-based bacterial motility and cell-to-cell spread . In the same region of ActA, several clusters of positively charged amino acids which could function as HS-binding domains were identified . An ActA-deficient mutant was significantly impaired in attachment and entry due to altered HS recognition functions . This work shows that specific interaction with an HSPG receptor present on the surface of both professional and nonprofessional phagocytes is involved in L . monocytogenes cytoadhesion and invasion and strongly suggests that the bacterial surface protein ActA may be a ligand mediating HSPG receptor recognition. Infect Immun, 1997 Jan, 65(1), 72 - 7 Requirement of the initial production of gamma interferon in the generation of protective immunity of mice against Listeria monocytogenes; Yang J et al.; Protective immunity of mice against Listeria monocytogenes, which is mediated mainly by gamma interferon (IFN-gamma)-producing T cells, was induced by immunization with viable bacteria but not with killed bacteria . By comparing mice immunized with either viable or killed L . monocytogenes, it was found that IFN-gamma was produced at the initial stage only after immunization with viable bacteria . This finding prompted us to investigate the effect of neutralizing the IFN-gamma on the final generation of protective T cells against L . monocytogenes . When endogenous IFN-gamma was neutralized by administration of anti-IFN-gamma monoclonal antibody for the initial 2 days in mice immunized with viable bacteria, the generation of protective T cells on day 6 was completely blocked, as revealed by T-cell adoptive transfer . The generation of listeria-specific IFN-gamma-producing T cells was also abolished . These results clearly demonstrated that endogenous IFN-gamma, which is produced at the initial stage of immunization, actually plays a critical role in the generation of protective T cells against L . monocytogenes in vivo . Moreover, this study suggested that the lack of IFN-gamma-inducing ability is responsible for the inability of killed L . monocytogenes to induce protective T cells in mice. J Clin Microbiol, 1997 Jan, 35(1), 179 - 83 Isolation of catalase-negative Listeria monocytogenes strains from listeriosis patients and their rapid identification by anti-p60 antibodies and/or PCR; Bubert A et al.; Two catalase-negative Listeria monocytogenes serovar 1/2b strains were isolated from listeriosis patients in 1995 in Germany . The infections appeared in individuals from different cities at different seasons and were caused by L . monocytogenes strains of different clonal types . In particular, the catalase reaction of one strain isolated from blood was consistently negative, whereas this reaction was only reversibly blocked when the strain was freshly isolated from ascitic fluid . After subculturing, the catalase-positive reaction was restored . Initially, identification of these isolates was difficult to achieve not only because of the lack of a catalase reaction, which generally distinguishes L . monocytogenes from other morphologically similar pathogenic gram-positive bacteria, but also because other routinely used biochemical tests such as CAMP and the commercial API test gave unclear results . However, rapid and unequivocal identification of these strains was possible by analyzing secretions of the p60 protein in culture supernatants by enzyme-linked immunosorbent assay or Western blot (immunoblot) analysis with our recently developed Listeria- and L . monocytogenes-specific anti-p60 antibodies . Additionally, the identifications were confirmed by Listeria- and L . monocytogenes-specific PCR analyses with primers derived from the iap, hly, and prfA genes . Immunoanalyses also allowed for the differentiation of these two strains, whereas no differentiation was possible by PCR when the internal, variable repetitive iap gene portion was analyzed . However, size variations of the PCR products comprising these gene portions which were obtained from a number of L . monocytogenes strains belonging to the same serotypes indicated that this type of PCR is not only useful for specific identifications but may be used in parallel as an additional marker for epidemiological studies . In conclusion, the data suggest that catalase production should not be taken as a strict criterion for the identification of listeriae . Furthermore, at least the infection caused by the stably catalase-negative strain supports the notion that catalase does not seem to be necessary for the intracellular growth of L . monocytogenes. FEMS Immunol Med Microbiol, 1996 Dec 31, 16(3-4), 291 - 8 The protective role of endogenous cytokines in host resistance against an intragastric infection with Listeria monocytogenes in mice; Nishikawa S et al.; It has been demonstrated that endogenous cytokines including gamma-interferon (IFN-gamma), tumour necrosis factor-alpha (TNF-alpha), and interleukin-6 (IL-6) play a protective role but that IL-4 plays a detrimental role in systemic Listeria monocytogenes infection in mice . The diverse roles of IL-10 have been reported in antilisterial resistance . In this paper, we studied the role of endogenous cytokines in host resistance against an intragastric infection with L . monocytogenes in mice . The expression of cytokine mRNAs including IFN-gamma, TNF-alpha, IL-4, IL-6, or IL-10, which were amplified by reverse transcription-PCR, was observed in intestinal intraepithelial lymphocytes irrespective of L . monocytogenes infection . Increased numbers of L . monocytogenes were detected in the ileal contents of infected mice which received monoclonal antibodies (mAbs) against IFN-gamma, TNF-alpha, IL-4, IL-6, or IL-10 . By contrast, mAbs against IL-4 or IL-6 showed little effect on the growth of L . monocytogenes in the mesenteric lymph nodes (MLNs), spleen, and liver, but anti-IFN-gamma mAb and anti-TNF-alpha mAb suppressed the defense in these organs . Anti-IL-10 mAb enhanced bacterial elimination from the MLNs but not from the spleen or liver . These results suggest that the role of endogenous cytokines may differ between systemic and intestinal defenses. FEMS Immunol Med Microbiol, 1996 Dec 31, 16(3-4), 257 - 66 Involvement of various combinations of endogenous inflammatory cytokines in Listeria monocytogenes-induced expression of inducible nitric oxide synthase in mice; Xiong H et al.; Using a in vitro infection of spleen cells with Listeria monocytogenes, the relationship between endogenous cytokines and the expression of inducible nitric oxide synthase (iNOS) was examined . When all interferon (IFN)-gamma, tumor necrosis factor (TNF)-alpha and interleukin (IL)-1 alpha, or the combination of IFN-gamma with either TNF-alpha or IL-1 alpha were neutralized by antibodies, there was a significant reduction of iNOS expression and nitrite production in culture . However, there was no reduction of iNOS expression and nitrite production when these cytokines were individually neutralized . After the depletion of natural killer cells, there was no change in the expression of Listeria-induced iNOS and nitrite production although the IFN-gamma production was abrogated . Neutralization of TNF-alpha and IL-1 alpha in natural killer cell-depleted culture resulted in the reduction of iNOS expression . Thus, various combinations of cytokines to play an important role in iNOS induction by L . monocytogenes. FEMS Immunol Med Microbiol, 1996 Dec 31, 16(3-4), 213 - 22 Expression of listeriolysin O by intracellular Listeria monocytogenes following infection of lipopolysaccharide-treated or untreated J774.1 macrophage-like cells; Moriishi K et al.; Listeria monocytogenes replicates in a phagocytic cell following escape into the host cytoplasm . Listeriolysin O, secreted by L . monocytogenes, which belongs to the thiol-activated hemolysin family, is known to play an important role in the escape of the bacterium into the host cytoplasm . In this study, we demonstrated that expression of listeriolysin O by infecting L . monocytogenes was lightly induced in J774.1 macrophage-like cells pretreated with lipopolysaccharide, although the growth of the bacteria was suppressed . The number of viable L . monocytogenes decreased until 4 h post-infection and then increased between 4 and 8 h post-infection in untreated J774.1 host cells, but it decreased until 8 h post-infection in lipopolysaccharide-treated host cells . However, expression of listeriolysin O by L . monocytogenes was not induced in the untreated host cells, while it increased 0 and 4 h post-infection in the lipopolysaccharide-treated host cells . Expression of listeriolysin O mRNA in the lipopolysaccharide-like cells . These results suggest that macrophage activation induced with lipopolysaccharide could lead to the expression of the listeriolysin O gene and the synthesis of listeriolysin O protein under suppression of the intracellular growth of L . monocytogenes. J Dairy Sci, 1996 Dec, 79(12), 2189 - 95 Bovine mastitis caused by Listeria monocytogenes: kinetics of antibody responses in serum and milk after experimental infection; Bourry A et al.; The kinetics of antibodies in serum and milk directed against proteins from Listeria monocytogenes were studied using 4 lactating cows after infection was experimentally induced in the udder with four strains of serotypes 4b or 1/2a . Antibodies (IgG and IgA) in samples of composite quarter milk and serum of the cow were measured by indirect ELISA . Microtiter plates were coated with proteins obtained from the culture supernatant of L . monocytogenes 4b . After challenge, an IgG response in serum and milk to listerial infections in the udder occurred for all cows, although the response varied among cows . In sera, the IgG titers reached a peak at 9 to 13 wk after challenge and remained elevated until 21 to 33 wk after challenge . In milk, the IgG titer increased significantly 3 wk after the challenge for all cows . A weak and nonpersistent increase in IgA antibodies also occurred . These results indicate that IMI by L . monocytogenes induced an increase of antibodies in milk, which could be detected with an ELISA test using our antigenic preparation . Therefore, this antigenic preparation could be used for the evaluation of a new method of diagnosis for bovine mastitis caused by L . monocytogenes. Immunology, 1996 Dec, 89(4), 532 - 8 Th0-like CD4+ T cells protect mice with murine retrovirus-induced immunodeficiency syndrome (MAIDS) against co-infection with Listeria monocytogenes; Hiromatsu K et al.; We examined the host defence mechanism against infection with Listeria monocytogenes, a facultative intracellular bacterium, in mice with murine acquired immunodeficiency syndrome (MAIDS) caused by LP-BM5 murine leukaemia virus (MuLv) infection . Although LP-BM5 MuLV infection in C57BL/6 mice leads to a stage of immunodeficiency characterized by severe compromise of cell-mediated immunity, the mice with established MAIDS infected with LP-BM5 8 weeks previously, showed resistance to an intraperitoneal infection with Listeria monocytogenes . These MAIDS mice also showed resistance to a lethal dose of secondary listerial challenge, while the delayed-type hypersensitivity response to heat-killed Listeria (HKL.) was severely impaired in MAIDS mice . The resistance of MAIDS mice to listerial infection was mediated by CD4+ alpha beta T cells but neither by gamma delta T cells nor natural killer (NK) cells . Interferon-gamma (IFN-gamma) and interleukin-10 (IL-10) were produced by CD4+ T cells from Listeria-infected MAIDS mice in response to the in vitro stimulation with HKL, whereas IFN-gamma but not IL-10 were produced by those from Listeria-infected control mice . These results suggest that T-helper 0 (Th0)-like immune responses of CD4+ T cells occur and participate in host defence mechanisms against listerial infection in MAIDS mice. Epidemiol Infect, 1996 Dec, 117(3), 437 - 42 Listeria species in domestic environments; Beumer RR et al.; Using a direct isolation method Listeria spp . were detected in 101 (47.4%) of 213 houses investigated . L . monocytogenes was present in 45 houses (21.1%) . Listeria spp . occurred at all sampling sites . Dish-cloths (37%) and surface samples round the drain in the bathroom (27.2%) were most frequently contaminated . Highest numbers (c . 10(4) c.f.u./object) were found in dish-cloths and washing-up brushes . Lower levels (up to 10(3) c.f.u./object) were obtained from kitchen sinks, refrigerator vegetable compartment samples and tooth brushes . In total, 132 isolations of Listeria spp . were made from 871 samples . L . innocua (53%) and L . monocytogenes (41%) were the predominant species in the positive samples . Other Listeria spp . were found in only 6% of the positive samples. Epidemiol Infect, 1996 Dec, 117(3), 429 - 36 A foodborne outbreak of gastroenteritis involving Listeria monocytogenes; Salamina G et al.; An outbreak of gastroenteritis occurred in Italy among 39 persons who had attended a private supper . All guests were previously healthy, young, non-pregnant adults; 18 (46%) had symptoms, mostly gastrointestinal (78%), with a short incubation period . Four were hospitalized with acute febrile gastroenteritis, two of whom had blood cultures positive for Listeria monocytogenes . No other microorganisms were recovered from the hospitalized patients' specimens . Epidemiological investigation identified rice salad as the most likely vehicle of the food-borne outbreak . L . monocytogenes was isolated from three leftover foods, the kitchen freezer and blender . Isolates from the patients, the foods and the freezer were indistinguishable: serotype 1/2b, same phage type and multilocus enzyme electrophoretic type . Eight (36%) of 22 guests tested were found to have antibodies against L . monocytogenes, compared with none of 11 controls from the general population . This point source outbreak was probably caused by infection with L . monocytogenes . Unusual features included the high attack rate among immunocompetent adults and the predominance of gastrointestinal symptoms. J Appl Bacteriol, 1996 Dec, 81(6), 641 - 50 The incidence and level of Listeria monocytogenes contamination of food sources at primary production and initial processing; Fenlon DR et al.; Listeria monocytogenes was isolated in low numbers from a variety of environmental samples associated with the primary production of food, including vegetation, faeces and meat . The organism was rarely detected on growing grass and vegetables prior to processing . The excretion of L . monocytogenes by farm animals was linked to their diet, with animals fed entirely on hay or manufactured diets not excreting detectable levels of Listeria (i.e . absence in 25 g) . However, animals fed on silage, which is frequently contaminated with L . monocytogenes, commonly excreted the organism . Transport of live animals over long distances (> 100 km) significantly increased the level of excretion of Listeria, but the contamination of carcasses of sheep and cattle was not high . Pigs and poultry faeces were free of Listeria prior to slaughter and pig carcasses were not found to have Listeria present . Frozen and chilled chicken did show detectable levels reflecting the greater potential for contamination during poultry processing . Samples of minced beef were tested and 21 of 23 samples were positive for L . monocytogenes, demonstrating that processing significantly increases the level of contamination compared to whole carcasses . Multilocus enzyme electrophoresis of a representative selection of the isolates showed that there was a wide range of electrophoretic types present in the primary production environment, relatively few of which have been linked to cases of human listeriosis . However, these types do arise on farms and occasional contamination of food raw material by potentially virulent strains may be sufficient to allow adaptable strains to become established in the processing environment and thus be responsible for more widespread contamination of the food available to the consumer. Biophys J, 1996 Dec, 71(6), 3030 - 45 Cell motility driven by actin polymerization; Mogilner A et al.; Certain kinds of cellular movements are apparently driven by actin polymerization . Examples include the lamellipodia of spreading and migrating embryonic cells, and the bacterium Listeria monocytogenes, that propels itself through its host's cytoplasm by constructing behind it a polymerized tail of cross-linked actin filaments . Peskin et al . (1993) formulated a model to explain how a polymerizing filament could rectify the Brownian motion of an object so as to produce unidirectional force (Peskin, C., G . Odell, and G . Oster . 1993 . Cellular motions and thermal fluctuations: the Brownian ratchet . Biophys . J . 65:316-324) . Their "Brownian ratchet" model assumed that the filament was stiff and that thermal fluctuations affected only the "load," i.e., the object being pushed . However, under many conditions of biological interest, the thermal fluctuations of the load are insufficient to produce the observed motions . Here we shall show that the thermal motions of the polymerizing filaments can produce a directed force . This "elastic Brownian ratchet" can explain quantitatively the propulsion of Listeria and the protrusive mechanics of lamellipodia . The model also explains how the polymerization process nucleates the orthogonal structure of the actin network in lamellipodia. Fundam Appl Toxicol, 1996 Dec, 34(2), 228 - 39 Immune function and host defense in rodents exposed to 60-Hz magnetic fields; House RV et al.; This study was conducted to evaluate the influence of subchronic exposure to pure, linearly polarized 60-Hz magnetic fields (MF) on the host immune response in mice . The experimental design was as follows: three groups were exposed continuously (18.5 hr/day) to MF at field strengths of 0.02, 2, or 10 gauss (G), one group was exposed intermittently (1 hr on/1 hr off) to MF at a field strength of 10 G, and one group served as a sham control . Experimental endpoints included spleen and thymus weights and cellularity, antibody-forming cell (AFC) response, delayed-type hypersensitivity (DTH) response, splenic lymphocyte subset analysis, susceptibility to infection with Listeria monocytogenes, and natural killer (NK) cell activity . No differences in body weight, lymphoid organ weight, or lymphoid organ cellularity were observed in any MF-exposed group in comparison to sham controls . Likewise, no statistically significant differences were found in comparisons of AFC responses . Isolated statistically significant differences from control were observed in MF-exposed mice in the DTH assay, although no clear dose-related pattern of altered activity was seen . Splenic lymphocyte subset parameters examined were within normal limits in all groups, and no differences between control and MF-exposed mice were found . Host resistance to bacterial infection was not altered at any MF exposure examined in this study . Finally, although apparently dose-related, statistically significant alterations were observed in an initial study of NK cell function, repeat studies failed to demonstrate a consistent pattern of alteration. Appl Environ Microbiol, 1996 Dec, 62(12), 4410 - 6 Purification and amino acid sequences of piscicocins V1a and V1b, two class IIa bacteriocins secreted by Carnobacterium piscicola V1 that display significantly different levels of specifi