Blood, 1993 Sep 15, 82(6), 1695 - 700 Results of fludarabine and prednisone therapy in 264 patients with chronic lymphocytic leukemia with multivariate analysis-derived prognostic model for response to treatment; O'Brien S et al.; Two hundred sixty-four patients with chronic lymphocytic leukemia were treated with fludarabine 30 mg/m2 intravenously for 30 minutes each day for 5 days and with prednisone 30 mg/m2 orally each day for 5 days . Courses were repeated monthly . Of the 264 patients . 125 patients (47%) had Rai stage III-IV disease; 169 patients (64%) were previously treated with a median of 3 prior regimens; and 138 of them (82%) were refractory to therapy with alkylating agents . The overall response (OR) and complete response (CR) rates in the 169 previously-treated patients were 52% and 37%; these were 74% and 63%, respectively, in Rai stage O-II patients and declined to 64% and 46%, respectively, in Rai III-IV disease . Among the previously untreated patients, the OR and CR rates were 79% and 63%, these being 85% and 70%, respectively, in Rai O-II patients, and declining to 64% and 46%, respectively, in Rai III-IV disease . The incidence of minor infections or fever of unknown origin was similar in all patient groups and occurred in 22% of courses . The incidence of sepsis and/or pneumonia was significantly correlated with the extent of prior therapy and with Rai stage, and ranged from 3% of courses in the previously untreated Rai O-II patients, to 13% of courses in the previously treated Rai III-IV patients . Listeria sepsis or Pneumocystis carinii pneumonia was noted in 14 patients . With therapy, CD4 levels were uniformly depressed from a median 1,015/microL pretreatment to a median 159/microL after 3 months of fludarabine therapy . Median time to progression in previously treated patients was 22 months . In previously untreated patients, median time to progression was 30 months for patients who achieved a partial remission and has not been reached in patients who achieved a CR with a median follow-up of 2 years . The median survival was 18 months for previously treated patients and has not been reached for previously untreated patients . Response rates in previously treated and untreated patients, as well as infection rates, were identical to those seen in 110 patients treated with the same dose schedule of fludarabine alone . Logistic regression analysis selected 4 factors to be significantly associated with worse response: Rai III-IV stage disease, prior therapy, older age, and low albumin levels . The regression equation was used to derive a probability of response based on the 4 characteristics . When the model was applied to the same population, patients could be divided into 4 prognostic groups with different outcomes. Commun Dis Rep CDR Rev, 1993 Sep 10, 3(10), R144 - 6 Listeriosis surveillance: 1992; Newton L et al.; The annual reported totals of cases of listeriosis in England, Wales and Northern Ireland have remained low over the last three years and a total of 108 cases was reported in 1992 . The clinical and epidemiological features reported in 1992 were similar to those in previous years and in other countries, except for a shift in the seasonal peak to the summer (a pattern consistently seen before the upsurge in 1987) and a reduction in the case fatality rate of non pregnancy-associated cases. Nature, 1993 Sep 2, 365(6441), 53 - 6 Different roles of alpha beta and gamma delta T cells in immunity against an intracellular bacterial pathogen; Mombaerts P et al.; Several bacterial pathogens of medical importance are able to persist and replicate inside host mononuclear phagocytes . Protective immunity depends on specific T lymphocytes that induce granulomatous lesions at the sites of bacterial multiplication . Listeria monocytogenes is an intracellular pathogen that replicates inside mononuclear phagocytes and hepatocytes of mice . Invasion from the phagosomal compartment into the cytoplasmic compartment is the principal mechanism of intracellular survival . Early in infection, resistance against L . monocytogenes is mediated by polymorphonuclear phagocytes which destroy infected liver cells, followed by natural killer cells which activate macrophages by means of interferon-gamma (refs 6, 7) . A specific immune response by T cells then develops which leads to sterile eradication of the microbes . T cells are also responsible for the highly effective protection in vaccinated mice against secondary infections . Although the role of alpha beta T cells has been demonstrated in these immune responses, that of gamma delta T cells is unclear . Here we use mice that selectively lack either alpha beta or gamma delta T cells as a result of targeted germ-line mutations in their T-cell receptor genes to investigate the relative roles of these T-cell populations during experimental infection with L . monocytogenes . We find that in primary listeriosis, either alpha beta or gamma delta T cells are sufficient for early protection . Resistance to secondary infection is mediated mainly by alpha beta T cells but also involves gamma delta T cells . Thus alpha beta T-cell-deficient mice can be rendered partially resistant by vaccination, and gamma delta T cells are shown to be responsible for this protective effect . In infected gamma delta T-cell-deficient mice we noticed the appearance of unusual liver lesions, indicating that gamma delta T cells have a unique regulatory role in this bacterial infection. Infect Immun, 1993 Sep, 61(9), 3901 - 6 Comparison of gamma interferon, tumor necrosis factor, and direct cell contact in activation of antimycobacterial defense in murine macrophages; Sypek JP et al.; We compared the abilities of gamma interferon (IFN-gamma), tumor necrosis factor alpha (TNF-alpha), and sensitized murine lymph node lymphocytes to activate syngeneic murine peritoneal macrophages to inhibit the growth of intracellular Mycobacterium bovis BCG in vitro . IFN-gamma could activate antimycobacterial defense only when added to macrophage cultures prior to their infection with BCG . TNF-alpha was without any effect . In contrast, BCG-sensitized lymphocytes could induce antimycobacterial defenses when added after macrophages had been infected with BCG . The cell-mediated effect required direct contact between effector lymphocytes and the targets (BCG-infected macrophages), as revealed in studies in which these cell populations were separated by a semipermeable membrane . Cyclosporin A, which inhibits the production of relevant macrophage-activating lymphokines, did not abrogate the ability of sensitized lymphocytes to activate antimycobacterial effects in infected macrophages . Furthermore, only BCG-sensitized lymphocytes, and not Listeria-sensitized lymphocytes, could activate the antimycobacterial effects . These lymphocytes were not cytotoxic to the infected macrophages . The presence of anti-TNF-alpha antibody in cocultures reduced the antimicrobial effects . We propose that the activation of antimycobacterial defense in macrophages can occur by direct physical contact with sensitized lymphocytes . This process may be due to lymphocyte membrane-associated TNF-alpha, as we previously demonstrated in our studies of antileishmanial defense. Infect Immun, 1993 Sep, 61(9), 3756 - 60 Intracytoplasmic growth and virulence of Listeria monocytogenes auxotrophic mutants; Marquis H et al.; The intracellular growth of several auxotrophic mutants of Listeria monocytogenes was examined in cell culture, and virulence was evaluated in mice by intravenous injection of log-phase bacteria . L . monocytogenes transposon insertion mutants requiring either uracil, phenylalanine, glycine, proline, or nicotinic acid for growth were fully virulent and grew similarly to the parental strain as shown by their growth rates in cell culture . Those requiring all three aromatic amino acids (phenylalanine, tryptophan, and tyrosine) or adenine were 1.5 log10 less virulent than the wild type . A threonine auxotroph, which showed enhanced growth in the presence of threonine-containing peptides as compared with that in the presence of free threonine, was approximately 1 log10 less virulent than the wild type . When host cells were deprived of specific amino acids required by both the host cell and L . monocytogenes, the bacteria continued to grow intracellularly . These studies suggest that the cytoplasm of eucaryotic cells behaves like rich medium, facilitating the growth of an intracellular bacterial pathogen with complex growth requirements . In addition, results related to amino acid deprivation during intracellular growth and specific extracellular growth requirements of a threonine auxotroph suggest that L . monocytogenes may utilize intracellular peptides as a source of amino acids. Infect Immun, 1993 Sep, 61(9), 3739 - 44 Analysis of cytokine mRNA expression in Listeria-resistant C57BL/6 and Listeria-susceptible A/J mice during Listeria monocytogenes infection; Iizawa Y et al.; This laboratory previously reported that mRNA expression for many cytokines, as determined by reverse transcription-polymerase chain reaction analysis, is induced rapidly in the spleen during murine listeriosis . In the present study, the patterns of cytokine mRNA expression in spleens and livers of Listeria-resistant C57BL/6 and Listeria-susceptible A/J mice were compared . In addition, in situ hybridization was performed to evaluate the distributions of cytokine mRNA-expressing cells in these tissues . Listeria-resistant C57BL/6 mice demonstrated greater expression of gamma interferon (IFN-gamma) and granulocyte-macrophage colony-stimulating factor (GM-CSF) mRNAs in the spleen than Listeria-susceptible A/J mice . Greater numbers of cells expressing IFN-gamma and GM-CSF mRNAs were observed by in situ hybridization in the spleens of C57BL/6 mice than in those of A/J mice . C57BL/6 and A/J mice did not differ in their expression of IFN-gamma mRNA in the liver . Nor did C57BL/6 and A/J mice differ in their expression of tumor necrosis factor alpha, interleukin-1 alpha (IL-1 alpha), IL-2, IL-4, or IL-6 mRNA in the liver or spleen, as determined by reverse transcription-polymerase chain reaction and in situ hybridization . These results indicate that the greater resistance of C57BL/6 mice to Listeria monocytogenes infection is associated with greater expression of IFN-gamma and GM-CSF mRNAs in the spleen and GM-CSF mRNA in the liver. Infect Immun, 1993 Sep, 61(9), 3664 - 72 Role of complement component C1q in phagocytosis of Listeria monocytogenes by murine macrophage-like cell lines; Alvarez-Dominguez C et al.; Listeria monocytogenes is a facultative intracellular pathogen of a great variety of cells . Among them, macrophages constitute the major effector cells of listerial immunity during the course of an infection . Although the molecular bases of L . monocytogenes attachment and entry to phagocytes are not completely understood, it has been demonstrated that C3b significantly increases L . monocytogenes uptake by macrophages via complement receptor type 3 . The first component of complement, C1q, is present in organic fluids at a relatively high concentration, and C1q receptor sites in macrophages are also abundant . In the present report, results of studies on the role of C1q in the internalization and infectivity of L . monocytogenes by macrophages are presented . L . monocytogenes uptake is enhanced by prior treatment of bacteria with normal sera . Heated serum or C1q-deficient serum abrogates this enhancement . Purified C1q specifically restored uptake . This effect was blocked by the addition of F(ab')2 anti-C1q antibody but not by an irrelevant matched antibody . Direct binding of C1q to L . monocytogenes was specific, saturable, and dose dependent with both fluorescent and radiolabeled C1q . N-Acetyl-D-alanyl-L-isoglutamine, diaminopimelic acid, and L-rhamnose caused a significant dose-dependent inhibition of C1q binding to bacteria, suggesting that these molecules, at least, are involved in the attachment of C1q to L . monocytogenes cell wall . When C1q binding structures on macrophage-like cells were blocked with saturating concentrations of C1q, the uptake of C1q-opsonized bacteria was less than in untreated cells . These experiments demonstrate that, in addition to other reported mechanisms, L . monocytogenes binds C1q, which mediates enhanced uptake by macrophages through C1q binding structures. J Exp Med, 1993 Sep 1, 178(3), 985 - 96 Intercellular interactions and cytokine responsiveness of peritoneal alpha/beta and gamma/delta T cells from Listeria-infected mice: synergistic effects of interleukin 1 and 7 on gamma/delta T cells; Skeen MJ et al.; Peritoneal gamma/delta T cells from Listeria-immune mice show an enhanced potential to expand when restimulated with antigens or mitogens in vitro (see companion paper {Skeen, M . J., and H . K . Ziegler . 1993 . J . Exp . Med . 178:971}) . When cocultured with peritoneal alpha/beta T cells, the gamma/delta T cell population expanded preferentially even when the in vitro stimulus was specific for the alpha/beta T cell population . Purified gamma/delta T cells did not respond to alpha/beta T cell-specific stimuli . If isolated T cell subsets were recombined in cell mixing experiments, the resulting proliferative response was greater than additive . Irradiated alpha/beta T cells could enhance the proliferation of responding gamma/delta T cells, but the effect was unidirectional; i.e., irradiated gamma/delta T cells did not stimulate responding gamma/delta T cells . This effect appeared to be cytokine mediated and did not require cell-cell contact . Both recombinant interleukin 2 (rIL-2) and rIL-7 could support the expansion of the gamma/delta T cells, while rIL-7 was only minimally stimulatory for the alpha/beta T cells . The magnitude of the response by gamma/delta T cells to rIL-7 exceeded the response to other in vitro stimuli, including immobilized anti-T cell receptor monoclonal antibody, and was 50-100-fold greater than the alpha/beta T cell response to IL-7 . This unique sensitivity of gamma/delta T cells to IL-7 was strongly enhanced by the presence of accessory cells . These cells could be replaced by rIL-1, establishing a synergy for IL-1 and IL-7 as factors that could uniquely stimulate this gamma/delta T cell population . Isolated peritoneal gamma/delta T cells from Listeria-immune mice react to heat-killed Listeria preparations in the presence of macrophages accessory cells in a non-H-2-restricted manner . Considered collectively, these results suggest a potential mechanism by which gamma/delta T cells can predominate in epithelial tissues and at sites of infection. J Exp Med, 1993 Sep 1, 178(3), 971 - 84 Induction of murine peritoneal gamma/delta T cells and their role in resistance to bacterial infection; Skeen MJ et al.; Previous studies have reported an association of gamma/delta T cells with microbial infection in both human lesions and murine infectious disease models . In this study we provide a comprehensive analysis of the conditions under which the induction of gamma/delta T cells occurs at a site of infection . We found a site-specific induction of gamma/delta T cells after the injection of Listeria monocytogenes in the peritoneal cavity of C3H mice . No changes were seen in the splenic or lymph node populations after these injections . Both the proportion and the absolute number of gamma/delta T cells increased in the peritoneal cavity . Additionally, when peritoneal T cells from Listeria-immune mice were restimulated in vitro, the induced gamma/delta T cells exhibited a greater expansion potential than the alpha/beta T cells . Neither the induced gamma/delta T cells nor those from normal mice expressed CD4 or CD8 on the cell surface . Thy-1 was expressed on only 29% of normal peritoneal gamma/delta T cells, but after intraperitoneal Listeria injection 65% of induced gamma/delta T cells expressed . Thy-1, Pgp-1 and CD45R expression on both normal and induced gamma/delta T cells was consistent with an activation phenotype . Significant increases in peritoneal gamma/delta T cells were not seen until 5-7 d after Listeria injection . The proportion of the CD3+ population expressing the gamma/delta T cell receptor remained elevated for 6-7 wk, while the absolute numbers of peritoneal gamma/delta T cells declined gradually over this time period, reflecting a decrease in both the number of lymphocytes and the percentage of these that were CD3+ . Peak numbers of gamma/delta T cells were seen at day 10 with live microbes such as Listeria . A variety of microbes, toxins, mitogens, antigens, cytokines, and nonspecific inflammatory agents were evaluated for their ability to induce gamma/delta T cells in the peritoneal cavity . Both Gram-positive and Gram-negative bacteria as well as Mycobacteria were able to induce gamma/delta T cells that showed increased in vitro expansion potential . An exotoxin from a Gram-positive organism, listeriolysin-o, and the lipopolysaccharide (LPS) endotoxin from a Gram-negative organism were also effective . gamma/delta T cell responses to LPS were under lps gene control . Peak numbers of gamma/delta T cells were observed at day 3 after injection with exotoxins and endotoxins . Modifications that abrogated the virulence of a bacterial strain also eliminated the inductive effect for gamma/delta T cells.(ABSTRACT TRUNCATED AT 400 WORDS) Int J Food Microbiol, 1993 Sep, 19(4), 271 - 81 The effects of diacetate with nitrite, lactate, or pediocin on the viability of Listeria monocytogenes in turkey slurries; Schlyter JH et al.; The antilisterial effects of sodium diacetate (0.1, 0.3 and 0.5%) alone or in combination with sodium nitrite (30 ppm), sodium lactate (2.5%) or pediocin (5000 arbitrary units/ml) were evaluated in slurries (25% meat in sterile deionized H2O) prepared from vacuum-packaged, ready-to-eat turkey breast meat and challenged with Listeria monocytogenes . In the absence of food additives, counts of L . monocytogenes increased from 4.5 log10 cfu/ml to ca . 8 log10 cfu/ml within 1 day at 25 degrees C and within 14 days at 4 degrees C . Similarly, the pathogen grew to ca . 8 log10 cfu/ml within 1 d at 25 degrees C and within 28 days at 4 degrees C in slurries containing nitrite or lactate . In the presence of pediocin, after an initial decrease of 0.9 log10 cfu/ml, numbers of the pathogen reached ca . 8 log10 cfu/ml within 5 days at 25 degrees C and within 28 days at 4 degrees C . However, 0.3 and 0.5% diacetate in turkey slurries were listericidal at 4 and 25 degree C, respectively . In the presence of nitrite with diacetate, there was no appreciable difference in growth of L . monocytogenes compared with diacetate alone . Antilisterial activity was potentiated in treatments containing lactate with 0.3% diacetate at 25 degrees C and lactate with 0.1% diacetate at 4 degrees C, compared to similar treatments containing diacetate or lactate alone . A listericidal effect (ca . 7 log10 cfu/ml difference compared to slurries without additives) was observed in treatments containing pediocin with 0.5% diacetate at 25 degrees C and pediocin with 0.3% diacetate at 4 degrees C . The pH of slurries containing 0.3 or 0.5% diacetate was 5.5 and 5.2, respectively, whereas nitrite (pH 6.2), lactate (pH 6.3) or pediocin (pH 6.2) in slurries had a negligible effect on pH compared to the control (pH 6.2) . The increased antilisterial activity in slurries with diacetate in combination with other additives was due to synergistic effects and not just pH . Thus, sodium diacetate alone can be used to delay growth of L . monocytogenes in turkey, and an additional level of safety can be achieved using diacetate in combination with sodium lactate or pediocin. Appl Environ Microbiol, 1993 Sep, 59(9), 3117 - 9 Development of a random amplification of polymorphic DNA typing method for Listeria monocytogenes; Lawrence LM et al.; The 10-mer primer OPM-01 (5'-GTT GGT GGC T-3') was used to generate random amplification of polymorphic DNA (RAPD) profiles by polymerase chain reaction for 91 strains of Listeria monocytogenes from raw milk, food, and veterinary, medical, and food-environmental sources . The profiles obtained contained 1 to 10 bands within the molecular size range of 0.5 to 5.0 kbp . Reproducibility was enhanced by annealing at low stringency and introducing a 1-min ramp time between annealing and extension temperatures . Thirty-three RAPD profiles were observed, with specific profiles being observed for strains from each source . RAPD profiles allowed discrimination within serogroups, although five RAPD profiles which were not confined to one serotype were found . Within food strains, one RAPD profile was more common than others, suggesting this to be a common type among strains from this source. Appl Environ Microbiol, 1993 Sep, 59(9), 2914 - 7 Biological inactivation of adhering Listeria monocytogenes by listeriaphages and a quaternary ammonium compound; Roy B et al.; The use of listeriaphages as a means of disinfecting contaminated stainless-steel and polypropylene surfaces was investigated . Surfaces artificially contaminated with L . monocytogenes 10401 and 8427 were sanitized with suspensions of listeriaphages (H387, H387-A, and 2671), all belonging to the Siphoviridae family . Phage suspensions at concentrations of up to 3.5 x 10(8) PFU/ml were at least as efficient as a 20 ppm solution of a quaternary ammonium compound (QUATAL) in reducing L . monocytogenes populations . A synergistic activity was observed when two or more phages were used in combination and when phages were suspended in QUATAL . The biological activity of the three phages was not affected by QUATAL concentrations of 50 ppm and a contact time of 4 h. Appl Environ Microbiol, 1993 Sep, 59(9), 2817 - 22 Application of multilocus enzyme electrophoresis in studies of the epidemiology of Listeria monocytogenes in Denmark; Norrung B et al.; A total of 245 strains of Listeria monocytogenes were investigated . These strains were isolated from human and animal cases of listeriosis as well as from different kinds of raw and processed foods . Thirty-three electrophoretic types (ETs) were identified among the 245 strains . The strains investigated included all human clinical strains isolated in Denmark during 1989 and 1990 . Seventy-three percent of the strains isolated in this period were assigned to one of only two ETs (ET 1 and ET 4) . ET 1, which was found to be the most frequently occurring ET among strains isolated from human clinical cases, was also found to occur rather frequently in animal clinical cases . ET 1 was, however, found only sporadically among strains isolated from foods and food factories . The data indicate that there might be something distinctive about the physiology or ecology of the ET 1 clone which makes it more likely to bring about disease in human beings either because of high pathogenicity or because of a special ability to multiply to infectious doses in processed foods . Another type, designated ET 4, was found to be the next most frequently occurring ET, after ET 1, among human clinical isolates . This could be explained by the fact that ET 4 was found to be the most frequently occurring ET within food isolates. J S Afr Vet Assoc, 1993 Sep, 64(3), 133 - 6 Generalised Listeria monocytogenes infection in a dog; Schroeder H et al.; A 6-year-old Doberman bitch was presented for an acute onset of circling, hemiparesis and depression . Clinical examination revealed conjunctivitis, abdominal pain, anaemia, decreased facial sensation, decreased jaw, tongue and pharyngeal tone, decreased conscious proprioception, decreased flexor withdrawal reflexes, and abnormal hemiwalking and hemistanding . Pancytopaenia was evident on haematological evaluation . Bone marrow cytology revealed a bacterial infection . Cerebrospinal fluid analysis was normal . Despite antibiotic treatment, the dog died . On autopsy, widespread multifocal inflammatory lesions were found to be present in the lungs, liver, spleen, meninges, lymph nodes, adrenal glands and kidneys . Listeria monocytogenes was isolated in pure culture from these organs and tissues . Histopathological examination showed numerous gram-positive intracellular rod-shaped bacteria seen in all the above-mentioned organs. Agents Actions, 1993 Sep, 40(1-2), 119 - 23 Influence of acetylsalicylic acid on a Listeria monocytogenes infection; Hockertz S et al.; The influence of acetylsalicylic acid (ASA, CAS 50-78-2) on the Listeria monocytogenes infection in balb/c mice was investigated . One day prior to lethal or sublethal infection, balb/c mice were treated intravenously with therapeutic concentrations of ASA alone or ASA in combination with murine recombinant interferon gamma, a lymphokine produced by T-helper cells . Three days post-infection, parasite burdens of spleen and liver were determined by the colony-forming unit assay . It was shown that the prophylactic application of ASA in a concentration of 5 mg/kg body weight resulted in a more than 10-fold reduction of viable Listeria monocytogenes in spleen and liver of balb/c mice . In addition, the combination of a suboptimal dosage of interferon gamma with ASA resulted in a significantly higher survival rate compared to the untreated controls. Mol Microbiol, 1993 Sep, 9(6), 1247 - 54 Induction of phagocytic behaviour in human epithelial cells by Escherichia coli cytotoxic necrotizing factor type 1; Falzano L et al.; Cytotoxic necrotizing factor type 1 (CNF1) from strains of pathogenic Escherichia coli induces in human epithelial HEp-2 cells, a profound reorganization of the actin cytoskeleton into prominent stress fibres and membrane ruffles . We report here that this process is associated with induction of phagocytic-like activity . CNF1-treated cells acquired the ability to ingest latex beads as well as non-invasive bacteria such as Listeria innocua, which were taken as a model system . Uptake of bacteria was similar to pathogen-induced phagocytosis, since L . innocua transformed with DNA coding for the pore-forming toxin listeriolysin O behaved, with respect to intracellular growth, like the invasive, pathogenic species L . monocytogenes . Our results raise the possibility that, in vivo, pathogenic CNF1-producing E . coli may invade epithelia by this novel induced phagocytic-like mechanism. Mol Microbiol, 1993 Sep, 9(5), 931 - 41 Internalin-mediated invasion of epithelial cells by Listeria monocytogenes is regulated by the bacterial growth state, temperature and the pleiotropic activator prfA; Dramsi S et al.; Entry of Listeria monocytogenes into epithelial cells requires expression of inIA, the first gene of an operon comprising two genes: inIA, which encodes internalin, a 800-amino-acid protein, and inIB, which encodes a 630-amino-acid protein . We report here that the inI locus is transcribed on two transcripts in constant relative ratio: a 5 kb transcript spanning inIA and inIB, and a 2.9 kb transcript that covers only inIA . The promoter is located 397 bp from the GTG initiator of inIA and displays in its -35 region a palindrome similar to that found in promoters controlled by the pleiotropic activator prfA . Transcription of the inI locus is, as are several other L . monocytogenes virulence genes, activated by prfA and regulated by temperature--with higher expression at 37 degrees C versus 25 degrees C--and bacterial growth state . It is maximal during exponential growth and correlates with maximal invasivity of the bacteria in the human epithelial cell line Caco-2 . It also correlates with maximum amounts of internalin present on the bacterial surface . Internalin is also detected in substantial amounts in culture supernatants . Taken together, these data suggest that surface-bound internalin plays an important role in bacterial entry but do not exclude a role for the released form. J Immunol, 1993 Sep 1, 151(5), 2742 - 52 Isolation of a macrophage-like cell line defective in binding of lipopolysaccharide . Influence of serum and lipopolysaccharide chain length on macrophage activation; Kirikae T et al.; A mutant cell line (J7.DEF.3) derived from murine macrophage-like J774.1 cells, was isolated on the basis of defective specific 125I-labeled LPS-binding in the presence of serum . Although J7.DEF.3 cells still respond to LPS in inducing TNF-alpha release and nitric oxide (NO) formation, these cells nevertheless showed significantly decreased responsiveness to LPS relative to the J774.1 parent . Under serum-free conditions, no differences between J774.1 and J7.DEF.3 cells in response to LPS were observed . The time kinetics of responsiveness to LPS also showed a delay in the onset of TNF-alpha release and NO formation in the mutant cells relative to parent cells . Importantly, this decrease in responsiveness to LPS relative to parental cells was dependent on the length of the polysaccharide portion of LPS . The defect in the mutant cells has been shown to be specific for LPS, in that these cells respond to heat-killed Listeria monocytogenes and to zymosan to a similar extent as do the parental cells . Collectively these results suggest that the defect in the J7.DEF.3 mutant cells may be related to a cellular LPS-binding molecule that, in turn, may depend upon an LPS-binding serum component. Nature, 1993 Aug 26, 364(6440), 798 - 802 Mice lacking the tumour necrosis factor receptor 1 are resistant to TNF-mediated toxicity but highly susceptible to infection by Listeria monocytogenes; Rothe J et al.; Tumour necrosis factor (TNF), jointly referring to TNF alpha and TNF beta, is a central mediator of immune and inflammatory responses; its activities are mediated by two distinct receptors, TNFR1 (p55) and TNFR2 (p75) (reviewed in refs 1-3) . The cytoplasmic domains of the TNFRs are unrelated, suggesting that they link to different intracellular signalling pathways . Although most TNF responses have been assigned to one or the other of the TNF receptors (mostly TNFR1), there is no generally accepted model for the physiological role of the two receptor types . To investigate the role of TNFR1 in beneficial and detrimental activities of TNF, we generated TNFR1-deficient mice by gene targeting . We report here that mice homozygous for a disrupted Tnfr1 allele (Tnfr1(0)) are resistant to the lethal effect of low doses of lipopolysaccharide after sensitization with D-galactosamine, but remain sensitive to high doses of lipopolysaccharide . The increased susceptibility of Tnfr1(0)/Tnfr1(0) mutant mice to infection with the facultative intracellular bacterium Listeria monocytogenes indicates an essential role of TNF in nonspecific immunity. Immunology, 1993 Aug, 79(4), 594 - 9 Inhibition of interferon-gamma by an interferon-gamma receptor immunoadhesin; Haak-Frendscho M et al.; Interferon-gamma (IFN-gamma) is an important cytokine which regulates inflammatory and immune response mechanisms . IFN-gamma enhances the presentation and recognition of antigens by inducing the expression of major histocompatibility complex (MHC) proteins, by activating effector T cells and mononuclear phagocytes, and by modulating immunoglobulin production and class selection in B cells . Inappropriate production of IFN-gamma has been implicated in the pathogenesis of several autoimmune and inflammatory diseases and in graft rejection . Here, we describe a recombinant inhibitor of IFN-gamma, termed murine IFN-gamma receptor immunoadhesin (mIFN-gamma R-IgG) . We constructed this immunoadhesin by linking the extracellular portion of the mouse IFN-gamma R to the hinge and Fc region of an IgG1 heavy chain . Murine IFN-gamma R-IgG is secreted by transfected cells as a disulphide-bonded homodimer which binds IFN-gamma bivalently, with high affinity and in a species-specific manner . In vitro, mIFN-gamma R-IgG can block mIFN-gamma-induced antiviral activity and expression of the class I MHC antigen H-2Kk in cultured cells . In vivo, mIFN-gamma R-IgG can block the function of endogenous mIFN-gamma in mouse models of infection with Listeria monocytogenes and of contact sensitivity . These results show that mIFN-gamma R-IgG is an effective and specific inhibitor of mIFN-gamma both in vitro and in vivo . Thus, in general, IFN-gamma receptor immunoadhesins may be useful for investigating the biological functions of IFN-gamma as well as for preventing deleterious effects of IFN-gamma in human disease. FEMS Immunol Med Microbiol, 1993 Aug, 7(2), 131 - 4 Serological response in rabbits to Listeria monocytogenes after oral or intragastric inoculation; Belen Lopez M et al.; The serological response in rabbits against Listeria monocytogenes after oral or intragastric inoculation was investigated . Both the number of sero-positive animals and the average serum titres were higher in animals inoculated by the oral route . This difference was especially marked in rabbits inoculated with the lower dose (1 x 10(3) colony-forming units (cfu)), which developed a strong serological response (average serum titre of 1280 after 4 inoculations) in most of the inoculated animals (80%), without any clinical signs . The implication of these results in the epidemiology of listeriosis is discussed. Clin Infect Dis, 1993 Aug, 17(2), 267 - 9 Liver abscess due to Listeria monocytogenes: case report and review; Braun TI et al.; Involvement of the liver in cases of Listeria monocytogenes infection is uncommon but has been manifested as solitary liver abscess, multiple liver abscesses, and hepatitis . We describe a 73-year-old diabetic woman who presented with a solitary liver abscess and prolonged fever, and we review the world literature on hepatic manifestations of L . monocytogenes infection . Patients presenting with solitary liver abscesses uniformly recovered with antimicrobial therapy and abscess drainage, whereas almost all patients presenting with multiple liver abscesses died. Clin Infect Dis, 1993 Aug, 17(2), 224 - 7 Increased risk of meningitis and bacteremia due to Listeria monocytogenes in patients with human immunodeficiency virus infection; Jurado RL et al.; The incidence, demographics, and clinical outcome of infections due to Listeria monocytogenes in individuals infected with the human immunodeficiency virus (HIV) were evaluated by prospective population-based surveillance . During a 2-year study period, 37 cases of invasive listeriosis occurred in metropolitan Atlanta (annual incidence, 0.8 case per 100,000 population) . Seven of these cases occurred in known HIV-infected individuals (19% of all cases); five had an AIDS-defining illness, and the other two had CD4 lymphocyte cell counts of < 200/microL . The estimated incidence of listeriosis among HIV-infected patients in metropolitan Atlanta was 52 cases per 100,000 patients per year, and among patients with AIDS it was 115 cases per 100,000 patients per year, rates 65-145 times higher than those among the general population . HIV-associated cases occurred in adults who were 29-62 years of age and in postnatal infants who were 2 and 6 months of age . Mortality among the HIV-infected group was 29% . L . monocytogenes serotypes 1/2a, 1/2b, and 4b were isolated from the HIV-infected patients . L . monocytogenes is an important opportunistic pathogen in HIV-infected patients. J Dairy Res, 1993 Aug, 60(3), 421 - 9 Growth of Listeria monocytogenes in Camembert and other soft cheeses at refrigeration temperatures; Back JP et al.; Listeria monocytogenes survived and, under most conditions, multiplied when inoculated directly into the cheese milk of laboratory made Camembert cheeses . The rate and extent of growth was reduced at lower storage temperatures . Significantly higher rates of growth occurred at the surface compared with the centre of the cheeses, and these were probably associated with increased pH and proteolysis at the cheese surface due to the mould ripening process . Similar results were obtained with Camenbert cheeses surface inoculated after manufacture . There was also temperature-dependent growth of List . monocytogenes on a range of inoculated commercially manufactured soft cheeses . Significant growth occurred in Cambazola, French and English Brie, blue and white Lymeswold, French Camembert and Brie with garlic . Little if any growth occurred in blue and white Stilton, Mycella, Chaume and full fat soft cheese with garlic and herbs at the temperatures examined. Appl Environ Microbiol, 1993 Aug, 59(8), 2743 - 5 Detection of Listeria monocytogenes with a nonisotopic polymerase chain reaction-coupled ligase chain reaction assay; Wiedmann M et al.; A polymerase chain reaction (PCR)-coupled ligase chain reaction (LCR) assay for the specific detection of Listeria monocytogenes (M . Wiedmann, J . Czajka, F . Barany, and C . A . Batt, Appl . Environ . Microbiol . 58:3443-3447, 1992) has been modified for detection of the LCR products with a nonisotopic readout . When a chemiluminescent or a colorimetric substrate for the nonisotopic detection of the LCR products was used, the PCR-coupled LCR gave a sensitivity of 10 CFU of L . monocytogenes . The detection method with the chemiluminescent substrate Lumi-Phos 530 permitted detection of the LCR products in less than 3 h, so that the whole assay can be completed within 10 h. Appl Environ Microbiol, 1993 Aug, 59(8), 2690 - 7 A ribosomal DNA fragment of Listeria monocytogenes and its use as a genus-specific probe in an aqueous-phase hybridization assay; Emond E et al.; cDNAs were prepared from the total RNA of Listeria monocytogenes ATCC 19118 and used as probes to screen a genomic library of the same strain . Four clones were identified which contained ribosomal DNA fragments . Recombinant DNA from one of them was fractionated and differentially hybridized with the cDNA probes to RNA of L . monocytogenes and Kurthia zopfii . The resulting hybridization pattern revealed an HpaII fragment of 0.8 kb that was specific for the L . monocytogenes strain . The nucleotide sequence of this fragment showed 159 bases of the 3' end of the 16S rRNA gene, 243 bases of the spacer region, and 382 bases of the 5' end of the 23S rRNA gene . In dot blot hybridization assays, the 32P-labeled 784-bp fragment was specific only for Listeria species . Dot blot assays revealed that the 32P-labeled fragment can easily detect > or = 10 pg of total nucleic acids from pure cultures of L . monocytogenes, which corresponds to approximately 300 bacteria . This fragment was also used as a probe in an assay named the heteroduplex nucleic acid (HNA) enzyme-linked immunosorbent assay . In this system, the biotinylated DNA probe is hybridized in the aqueous phase with target RNA molecules and then specific HNAs are captured by HNA-specific antibodies . Captured HNA molecules are revealed with an enzyme conjugate of streptavidin . In a preliminary HNA enzyme-linked immunosorbent assay, the 784-bp fragment maintained its specificity for Listeria spp . and could detect 5 x 10(2) cells in artificially contaminated meat homogenate. Eur J Immunol, 1993 Aug, 23(8), 2005 - 10 Variable binding affinities of listeriolysin O peptides for the H-2Kd class I molecule; Wipke BT et al.; Previously we used the peptide-binding motif for the murine class I major histocompatibility complex molecule H-2Kd to identify a nonamer peptide of the Listeria monocytogenes listeriolysin (LLO) protein that was recognized by cytotoxic T lymphocytes (CTL) in association with H-2Kd . Eleven nonamer peptides contained in the LLO sequence were synthesized and one, LLO 91-99, proved to be a CTL target . Using peptide binding competition assays with H-2Kd-restricted CTL, we show that 3 out of the 11 LLO peptides, including the CTL epitope, have a high binding affinity for H-2Kd; 2 of 11 peptides have approximately 10-fold lower affinity, while the remaining 6 peptides have no or very low affinity for H-2Kd . Single residue changes were made in the LLO 91-99 peptide and two other LLO peptides to identify non-anchor amino acids that might interfere with peptide binding . In addition, we used the LLO peptides which bound well to H-2Kd to attempt to restimulate a secondary CTL response from L . monocytogenes-primed spleen cells . Only LLO 91-99 was able to induce such a response . Thus only a fraction of nonamer peptides which fit the original binding motif have a high affinity for the H-2Kd class I molecule, and only a fraction of these serve as CTL epitopes. J Immunol, 1993 Aug 1, 151(3), 1401 - 9 IFN-gamma inhibits the replication of Listeria monocytogenes in hepatocytes; Gregory SH et al.; We previously reported that the bulk of Listeria monocytogenes injected intravenously into mice is taken up in the liver and replicates within the parenchymal cells (hepatocytes) . Although IFN-gamma is known to play an important role in host defenses to listerial infections of the liver, the mechanism(s) that underlies this role remains to be fully delineated . In the initial experiments presented here, we demonstrated the elevated expression of IFN-gamma message in the livers of mice during primary listerial infections . Subsequent experiments showed that the listerial burden of the hepatocyte population was increased significantly in mice administered monoclonal anti-IFN-gamma . Conversely, the administration of murine rIFN-gamma resulted in a marked (2 log10) decrease in the number of hepatocyte-associated Listeria . In vitro, IFN-gamma stimulated the listericidal activity of purified hepatocytes . Infected hepatocytes incubated in the presence of > 0.1 U/ml murine rIFN-gamma exhibited a significant reduction in intracellular Listeria . The elevated antilisterial activity of IFN-gamma-treated hepatocytes in culture was abrogated by the presence of compounds that scavenged or inhibited the production of reactive oxygen intermediates . Taken together, these findings suggest that activation of the oxygen-dependent, antimicrobial activity of hepatocytes may constitute a principal effector function of IFN-gamma in host defenses to listerial infections of the liver. Immunobiology, 1993 Aug, 188(4-5), 355 - 69 The effect of adult thymectomy on immune response to infection with Listeria monocytogenes in mice; Zhang XY et al.; The role of adult thymus in in vivo immune response to infection with Listeria monocytogenes was examined using euthymic mice and adult-thymectomized (ATx) mice which had been thymectomized 2 weeks before . Numbers of T cells in peritoneal cavities and spleens were increased at 2 weeks after inoculation of L . monocytogenes, whereas such increases of T cells were several times higher in euthymic mice than in ATx mice . In flow-cytometric analysis of peritoneal exudate cells, a significant increase of CD3+CD4-CD8- cells bearing gamma/delta type T cell receptor was noted in euthymic mouse after infection compared to ATx mouse . Neither assay of antigen-specific T cell proliferation nor analysis of cell cycle exhibited any superiority of T cells obtained from euthymic mice to those obtained from ATx mice . These findings suggest that the enlargement of T cell population in euthymic mice is attributed largely to T cells which emigrate from the thymus after inoculation of L . monocytogenes . Moreover, in vivo protective immune response against secondarily challenged L . monocytogenes was achieved more efficiently in euthymic mice than in ATx mice, as shown by the clearance of the bacteria from organs and the survival rate of infected mice . Our results indicate the importance of adult thymus-dependent increase of T cells in eliminating the facultative intracellular bacteria such as L . monocytogenes. Int J Food Microbiol, 1993 Aug, 19(3), 229 - 37 Incidence of Listeria species in raw and pasteurized milk produced in São Paulo, Brazil; Moura SM et al.; The present study evaluated the incidence of Listeria spp . in raw and pasteurized milk from a Brazilian dairy plant . Ten samples of each type of milk (raw types B and C and pasteurized types B and C) were collected monthly from October 1989 to September 1990 (except in December), comprising 440 samples (110 samples of each type of milk) . The recovery of Listeria spp . was carried out using LPM (lithium chloride phenylethanol moxalactam) and MOX (modified Oxford) agars, after a two-step enrichment procedure in Listeria enrichment broth (LEB) and Fraser broth . Overall, 12.7% of raw milk samples, 0.9% of pasteurized milk samples and 6.8% of total of milk samples were positive for Listeria spp., while 9.5% of raw milk samples, none of the pasteurized milk samples and 4.8% of total milk samples, were positive for Listeria monocytogenes . Raw milk also contained L . innocua (9.5%), L . welshimeri (0.9%) and L . grayi (0.4%) . Pasteurized milk contained only L . innocua (0.9%). Int J Food Microbiol, 1993 Aug, 19(3), 193 - 205 Occurrence and characteristics of Listeria in foods produced in Northern Ireland; Harvey J et al.; The incidence of L . monocytogenes and other Listeria species was determined for 513 food samples produced in Northern Ireland . Selected L . monocytogenes isolates were typed using MEE and RFLP analysis . The overall incidence of Listeria in the foods examined was 35% (Listeria monocytogenes 18.3%) . The incidence of Listeria and L . monocytogenes in four different food categories (graded I-IV according to decreasing extent of processing) being: I, 11.1% Listeria and 4.7% L . monocytogenes; II, 27.1% Listeria and 12.2% L . monocytogenes; III, 89.1% Listeria and 50% L . monocytogenes and IV, 100% Listeria and 100% L . monocytogenes . Within food categories I and II, the incidence of Listeria on occasions varied markedly between similar products produced by different processors . The most frequently isolated species was L . innocua, followed by L . monocytogenes, L . seeligeri and L . welshimeri . The L . monocytogenes isolates were predominantly serogroup 1 . A modified USDA method was the most productive of four enrichment procedures investigated . Over the one-year duration of the survey, a distinctive Listeria microflora could be discerned in products from certain processors and was confirmed in some cases by MEE and RFLP typing of L . monocytogenes isolates. Appl Environ Microbiol, 1993 Aug, 59(8), 2698 - 705 Production and characterization of anti-DNA-RNA monoclonal antibodies and their application in Listeria detection; Fliss I et al.; Murine monoclonal antibodies (MAbs) specific for DNA-RNA hybrids were successfully produced with two different heteropolymers as antigens, cDNA-mRNA and phi X174 DNA-RNA heteroduplexes . The former was simpler to prepare . Both had shown similar immunogenicities . Two different immunoglobulin M MAbs were isolated . The 20D3 MAb, generated with the phi X174 DNA-RNA hybrid, showed association constants of 1.05 x 10(12), 2.12 x 10(10), and 1.68 x 10(7) for the antigens phi X174 DNA-RNA, cDNA-mRNA, and poly(rA)-poly(dT), respectively . The 6B5 MAb, obtained with the cDNA-mRNA hybrid, showed association constants of 1.59 x 10(5), 5 x 10(12), and 7.1 x 10(8) for the above-described antigens, respectively . With the 20D3 MAb, an immunoassay was developed for the detection of Listeria DNA-RNA hybrids . In brief, a biotinylated rRNA gene probe specific for the genus Listeria was hybridized with rRNA in the solution phase . The hybrids thus formed were then captured in microtiter plate wells precoated with the purified 20D3 MAb, and the probe-target hybrids were detected with a streptavidin-alkaline phosphatase conjugate . This assay was shown to be specific for the genus Listeria and highly sensitive, allowing the detection of as little as 2.5 pg of target rRNA. Epidemiol Infect, 1993 Aug, 111(1), 71 - 9 Comparison of multilocus enzyme electrophoresis (MEE), ribotyping, restriction enzyme analysis (REA) and phage typing for typing of Listeria monocytogenes; Norrung B et al.; The discriminatory power of four methods for typing of Listeria monocytogenes was compared . The four methods were multilocus enzyme electrophoresis (MEE), ribotyping, restriction enzyme analysis (REA), and a newly developed Danish phage typing system . Ninety-nine human clinical, food and slaughterhouse isolates of Listeria monocytogenes were typed by each method . The most discriminatory single typing method was phage typing with an overall discriminatory index (DI) of 0.88 followed by REA, MEE and ribotyping with DI-values at 0.87, 0.83 and 0.79 respectively . Considering strains from each of the two predominant O-serotypes alone, serotype 1 was best discriminated by the molecular typing methods, in particular REA, which showed a DI of 0.92 . The serotype 4 strains were best discriminated by phage typing (DI = 0.78) . If two or more typing methods were combined, the combination of REA and MEE were found to be the most discriminatory combination . The DI values were 0.96, 0.74 and 0.90 for serotype 1, 4, and both combined, respectively . Phage typing is a rapid and inexpensive typing method but not as reproducible as the molecular typing methods . It is the most suitable method for mass screening . In situations where results are required to be highly reliable, i.e . when studying the relationships between only a few strains, a single or a combination of molecular typing methods should be used, preferable MEE and REA. Infect Immun, 1993 Jul, 61(7), 3073 - 5 Detection of a prfA-independent promoter responsible for listeriolysin gene expression in mutant Listeria monocytogenes strains lacking the PrfA regulator; Domann E et al.; Expression of listeriolysin, a major virulence factor of pathogenic Listeria monocytogenes, is positively regulated by the pleiotropic virulence regulator PrfA . In this study, we demonstrate that L . monocytogenes strains lacking the prfA regulator gene produce listeriolysin in small, albeit detectable, amounts when analyzed in a hemolysin assay and by immunoblots with listeriolysin-specific monoclonal antibodies . Transcriptional analysis revealed the existence of a PrfA-independent promoter that was responsible for the hemolytic activity expressed by these strains. Infect Immun, 1993 Jul, 61(7), 3068 - 72 Multiplication of Listeria monocytogenes in a murine hepatocyte cell line; Wood S et al.; Listeria monocytogenes was shown to invade and multiply in a murine hepatocyte cell line (ATCC TIB73) . Hemolytic and nonhemolytic L . monocytogenes strains exhibited similar abilities to invade hepatocytes, but only hemolytic L . monocytogenes multiplied within this cell line . Microscopic evaluation of monolayers stained with Wright stain demonstrated focal necrosis (plaques) in the hepatocyte monolayers, with large numbers of intracellular listeriae visible within the hepatocytes that lined the margins of these plaques . Murine recombinant interleukin-1 alpha, human recombinant tumor necrosis factor alpha, and murine recombinant gamma interferon did not affect the multiplication of L . monocytogenes in the hepatocytes . These data confirm in vivo observations of the intracellular multiplication of L . monocytogenes in hepatic lesions in infected mice. Infect Immun, 1993 Jul, 61(7), 2793 - 802 Localization of the ActA polypeptide of Listeria monocytogenes in infected tissue culture cell lines: ActA is not associated with actin "comets"; Niebuhr K et al.; The ActA protein of the gram-positive pathogen Listeria monocytogenes is a 90-kDa polypeptide required for interaction of the bacteria with components of the host cell microfilament system to generate intra- and intercellular movement . To study the localization, distribution, and expression of the ActA polypeptide in L . monocytogenes grown either in broth culture or in infected tissue culture cells, we first isolated ActA by monoclonal antibody-based immunoaffinity chromatography . Polyclonal rabbit antisera raised against purified ActA revealed that ActA was associated with the cell wall and exposed on the surface of the bacteria, readily accessible to ActA antibodies . In contrast, a C-terminally truncated ActA1 polypeptide expressed by the isogenic actA1 mutant was detected only in the supernatant fluids . Immunofluorescence microscopy and electron microscopic studies using immunogold labeling showed that ActA was present on the surface of the bacteria infecting PtK2 and J774 cells at all stages of the infection cycle and was not found to be associated with the actin "tail" of individual bacteria . For the isogenic actA1 mutant strain, which grew as microcolonies within infected cells, only diffuse staining of the secreted ActA1 polypeptide in the host cytoplasm was observed . The ActA polypeptide therefore appears to be required in the initiation of actin accumulation by the bacterium and is apparently not directly involved in the generation of the actin tail . Analysis of strains of several L . monocytogenes serotypes indicated microheterogeneity in the molecular weights of the ActA polypeptides of individual strains and led to the detection of a serotype 3a strain that does not produce ActA. Infect Immun, 1993 Jul, 61(7), 2786 - 92 An anti-CD3 monoclonal antibody protects mice against a lethal infection with Listeria monocytogenes through induction of endogenous cytokines; Nakane A et al.; Mice were protected against a lethal infection with Listeria monocytogenes when treated with low doses of an anti-CD3 monoclonal antibody (MAb) . Injection of anti-CD3 MAb induced rapid production of endogenous tumor necrosis factor (TNF) in the spleens and endogenous gamma interferon (IFN-gamma) in the bloodstreams and spleens of mice . Administration of anti-Thy1.2 MAb or a combination of anti-CD4 MAb and anti-CD8 MAb resulted in suppression of anti-CD3 MAb-induced endogenous cytokine production and antilisterial resistance . Alternatively, in vivo depletion of anti-CD3 MAb-induced TNF and IFN-gamma by the simultaneous administration of antibodies against TNF and IFN-gamma suppressed anti-CD3 MAb-induced antilisterial resistance . Moreover, injection of anti-complement receptor type 3 (Mac-1, CD11b) resulted in inhibition of anti-CD3 MAb-induced antilisterial resistance . These results suggest that the preventive effect of anti-CD3 MAb might be due to activation of phagocytes by TNF and IFN-gamma induced by stimulating CD4+ T cells and CD8+ T cells with the MAb . Furthermore, treatment with anti-CD3 MAb did not inhibit establishment of acquired resistance against secondary infection with L . monocytogenes. J Cell Sci, 1993 Jul, 105 ( Pt 3), 699 - 710 Polarized distribution of Listeria monocytogenes surface protein ActA at the site of directional actin assembly; Kocks C et al.; The facultative intracellular pathogen Listeria monocytogenes can infect host tissues by using directional actin assembly to propel itself from one cell into another . The movement is generated by continuous actin assembly from one end of the bacterium into a tail, which is left behind in the cytoplasm . Bacterial actin assembly requires expression of the bacterial gene actA . We have used immunocytochemistry to show that the actA gene product, ActA, is distributed asymmetrically on the bacterial surface: it is not expressed at one pole and is increasingly concentrated towards the other . This polarized distribution of ActA was linked to bacterial division: ActA protein was not, or only faintly, expressed at the pole that had been formed during the previous division . On intracellular bacteria ActA was expressed at the site of actin assembly, suggesting that ActA may be involved in actin filament nucleation off the bacterial surface . We predict that the asymmetrical distribution of this protein is required for the ability of intracellular Listeria to move in the direction of the non-ActA expressing pole. J AOAC Int, 1993 Jul-Aug, 76(4), 831 - 8 Comparison of MICRO-ID Listeria method with conventional biochemical methods for identification of Listeria isolated from food and environmental samples: collaborative study; Higgins DL et al.; Fourteen laboratories participated in a collaborative study to evaluate the ability of the MICRO-ID Listeria identification method to correctly identify Listeria isolated from food and environmental sources . Each collaborator received 60 isolates consisting of 51 Listeria and 9 non-Listeria cultures . All isolates were identified by conventional biochemical analyses in the principal laboratory . Cultures were checked for purity by Gram staining and examined for oxidase and catalase activities . Only Gram positive, oxidase negative, catalase positive cultures were tested with the method . Colonies from trypticase soy agar with 0.6% yeast extract were suspended in 4.6 mL physiological saline to a MacFarland No . 1 turbidity standard and used to inoculate the test strip . In addition, the hemolytic reaction of each isolate was determined by using the Christie-Atkins-Munch-Peterson (CAMP) test and by stabbing sheep blood agar . Identification of Listeria is based on the octal code obtained from the strip and the hemolytic reaction of the isolate . The MICRO-ID Listeria method agreed with conventinal biochemical identification for 98.0% of L . monocytogenes, 77.1% of L . seeligeri, 90.0% of L . ivanovii, 96.4% of L . grayi/L . murrayi, 73.9% of L . welshimeri, and 100% of L . innocua isolates . A large percentage of errors in identification of the L . seeligeri and L . ivanovii cultures was caused by inaccurate reading of the CAMP and hemolysis tests rather than errors in the test strip . The method was adopted first action by AOAC International. J AOAC Int, 1993 Jul-Aug, 76(4), 822 - 30 AutoMicrobic System for biochemical identification of Listeria species isolated from foods: collaborative study; Harris L et al.; A collaborative study was conducted to evaluate the performance of the AutoMicrobic System Gram-Positive Identification (GPI) and Gram-Negative Identification (GNI) test kits to biochemically characterize Listeria spp . Thirteen laboratories each tested 97 food and environmental isolates, representing the 7 species of Listeria, as well as 11 additional genera of Gram-positive rods . Each collaborator inoculated both a GPI and a GNI card with a pure culture of each organism . The AutoMicrobic System identified the isolates and printed out the biochemical results . The GPI card is used to obtain a species identification and a mannitol reaction result, and the GNI card is used to obtain rhamnose and xylose reaction results . Organisms are classified into species groups and can be further distinguished on the basis of hemolysis or nitrate reduction tests . The AutoMicrobic System method correctly classified 90.8% of the Listeria spp . isolates and 100% of the non-Listeria isolates . The AutoMicrobic System method was adopted first action by AOAC International for the biochemical characterization of Listeria spp . isolated from food and environmental sources. Biophys J, 1993 Jul, 65(1), 316 - 24 Cellular motions and thermal fluctuations: the Brownian ratchet; Peskin CS et al.; We present here a model for how chemical reactions generate protrusive forces by rectifying Brownian motion . This sort of energy transduction drives a number of intracellular processes, including filopodial protrusion, propulsion of the bacterium Listeria, and protein translocation. Appl Environ Microbiol, 1993 Jul, 59(7), 2082 - 6 Sodium chloride, potassium chloride, and virulence in Listeria monocytogenes; Myers ER et al.; Virulence, as determined in a mouse model, and the virulence factor activities of catalase, superoxide dismutase, and listeriolysin O were examined in a parental strain (10403S) and in a nonhemolytic mutant strain (DP-L224) of Listeria monocytogenes . The cells were propagated in media containing various concentrations of sodium chloride or potassium chloride . Strains 10403S and DP-L224 exhibited significant increases in catalase activity and listeriolysin O activity when grown in medium containing either salt at 428 mM . The superoxide dismutase activities for both strains increased when they were grown in medium containing either salt . The superoxide dismutase activity was significantly increased only when cells were propagated in medium containing no salt compared with that when they were propagated in medium containing either salt at 1,112 mM . In addition, the listeriolysin O activity was highest for cells propagated in medium containing KCl at 428 mM, while the activity was significantly less for cells propagated in medium containing NaCl at an equal concentration . Virulence was examined in mouse livers and spleens after intravenous infection, and approximate 50% lethal doses were determined after intragastric and intraperitoneal infection . Each method of infection indicated that listeriolysin O is required for virulence, while growth in salt-containing medium or the production of higher levels of catalase, superoxide dismutase, and listeriolysin O do not appear to enhance the virulence of L . monocytogenes. Arch Int Pharmacodyn Ther, 1993 Jul-Aug, 324, 114 - 23 Effects of buspirone on the resistance, development and passive transfer of immunity to Listeria monocytogenes in mice submitted to stress; Freire-Garabal M et al.; Mice exposed to a chronic auditory stressor and treated chronically with buspirone (1 mg/kg) showed a reduction in stress-induced suppression of the resistance and development of immunity to Listeria monocytogenes . Attempts to passively transfer immunity with spleen cells were also performed . Stressed, immunized mice had a reduced capacity to transfer immunity passively to nonimmunized mice and buspirone was found to partially suppress this inhibitory effect of stress. Vet Microbiol, 1993 Jul, 36(1-2), 185 - 9 Comparison of a cold enrichment method and the IDF method for isolation of Listeria monocytogenes from animal autopsy material; Eld K et al.; The method most often used in Sweden for isolation of Listeria monocytogenes from animal autopsy material is a cold enrichment method . This method is very slow . The International Dairy Federation (IDF) has recently presented a method for detection of L . monocytogenes in milk and milk products that is complete in one week . During a two year period 69 specimens from dead animals with suspected listeriosis were examined for L . monocytogenes in parallel analyses with both the cold enrichment method and the IDF method . Samples derived from different autopsy material representing a variety of animals . L . monocytogenes was isolated in 27.5% of the samples with the IDF method but only in 4.3% with the cold enrichment method . It is concluded that the IDF method was more sensitive than the cold enrichment method. J Hepatol, 1993 Jul, 18(3), 284 - 9 Listeria monocytogenes hepatitis in a liver transplant recipient: a case report and review of the literature; Bourgeois N et al.; Listeria is an uncommon cause of hepatitis in adults . We report the case of a liver transplant recipient who presented with a clinical picture of acute hepatitis, 8 months after grafting . Blood cultures yielded Listeria monocytogenes . The patient made a full clinical recovery after adequate antimicrobial therapy (ampicillin and gentamicin intravenously for 4 weeks) . Hepatitis was attributed to the Listeria infection . We believe this is the first reported case of Listeria hepatitis in an organ transplant recipient. Immunol Lett, 1993 Jul, 37(1), 73 - 6 Production of interleukin 8 (IL-8) by cord blood mononuclear cells induced by Listeria monocytogenes; Serushago B et al.; The defective ability of human newborns to mobilize phagocytes to the site of infection led us to examine the ability of cord blood mononuclear cells to secrete interleukin-8, a major neutrophil chemotactic factor, in response to stimulation with Listeria monocytogenes . Adult or cord blood mononuclear cells were incubated with L . monocytogenes for varying lengths of time, and IL-8 was measured in the culture supernatants by the enzyme-linked immunosorbent assay (ELISA) . Spontaneous IL-8 secretion by unstimulated cells was undetectable or at the minimal detection limit of the assay . By 24 h of cell incubation with L . monocytogenes, newborn cells produced as much IL-8 as adult cells did (300 +/- 113 versus 269 +/- 189 ng/ml, respectively) . Over the next 2-4 days, IL-8 output by adult cells was slightly higher than that by newborn cells, but the difference was not statistically significant . The in vitro results suggested that newborns are as able as adults to produce IL-8, although they are defective in mobilizing neutrophils, the IL-8 target cells, to the site of infection. Z Geburtshilfe Perinatol, 1993 Jul-Aug, 197(4), 179 - 83 {Effect of Listeria on contractibility of human uterine muscle}; Lechner W et al.; In Austria the prevalence of listeriosis is 2.6 cases per million inhabitants yearly, hence rather rarely the cause of spontaneous abortion or premature birth . On the other hand, Listeria monocytogenes is found in 1% of the asymptomatic population as a component of stool flora . Since the cause of premature labour contractions remains unclear in about half of all cases, we examined 29 listeria strains for their ability to cause myometrial contraction by direct contact using an in-vitro uterine strip-model . Seven of nine L . monocytogenes strains were able to cause contractions; contractions were not inducible by an nonhaemolytic mutane (SLCC 53, avirulent) nor by a rough strain (SLCC 5779, only slightly virulent) . Three of six L . ivanovii isolates also exhibited the ability to induce contractions . None of the apathogenic species (L . innocua, L . seeligeri, L . welshimeri, L . grayi and L . murrayi) was capable of activating contractions in our in-vitro model . Only L . monocytogenes and L . ivanovii cause conjunctivitis after being dropped in rabbit's eyes (positive Anton Test) . The influence of listeria on uterine activity as found in our in-vitro model thus correlates with the classical pathogenicity test . We consider these in-vitro results as an additional argument to oppose the presence of L . monocytogenes in ready-to-eat foods. Lett Appl Microbiol, 1993 Jul, 17(1), 14 - 6 The effect of pH and temperature on haemolysin production by Listeria species; Khan SA et al.; The ability of three strains of Listeria monocytogenes NCTC 7973, serovar 1/2a, NCTC 5124m serovar 4a, C-274 serovar 4b and one strain of L . seeligeri (SLCC 3954) to grow in TPB (Tryptose phosphate agar) at pH values between 5-9 and produce haemolysin has been investigated at two incubation temperatures . The minimum and maximum pH values at which haemolysin was detected were 5 and 9 respectively, at 20 degrees and 32 degrees C. Epidemiol Infect, 1993 Jun, 110(3), 543 - 51 The contamination of paté by Listeria monocytogenes in England and Wales in 1989 and 1990; Gilbert RJ et al.; In July 1989, 1834 samples of pate (of which 1698 were from retail displays) were examined by the PHLS for the presence of Listeria monocytogenes . The survey was repeated in July 1990, when 626 pate samples on retail sale were examined . Between the two surveys there was a marked reduction in the proportions of pates contaminated (10% in 1989 and 4% in 1990) and in the numbers of samples from which > 10(3) L . monocytogenes/g were recovered . The higher rate of contamination detected in 1989 was largely due to pate from a single manufacturer . In both surveys, pate sold as loose slices had higher rates of contamination than those prepackaged . Temperature control had improved between the two surveys where 65% of samples in 1989 and 83% in 1990 were stored at < or = 7 degrees C . Although contamination occurred at almost all temperatures, L . monocytogenes was both quantitatively and qualitatively more common in samples stored at > 7 degrees C . The majority of pates had unexpired shelf lives of between 0 and 3 weeks . Although contamination occurred throughout the shelf life of these products, the proportion of samples where L . monocytogenes was recovered was higher in pates with expired sell by dates . There was an association between high total viable counts and the presence of L . monocytogenes . Likely routes of contamination of pate together with possible preventive measured are discussed. Proc Natl Acad Sci U S A, 1993 Jun 1, 90(11), 5034 - 8 Modulation of the interaction between G-actin and thymosin beta 4 by the ATP/ADP ratio: possible implication in the regulation of actin dynamics; Carlier MF et al.; The interaction of G-actin with thymosin beta 4 (T beta 4), the major G-actin-sequestering protein in motile and proliferating cells, has been analyzed in vitro . T beta 4 is found to have a 50-fold higher affinity for MgATP-actin than for MgADP-actin . These results imply that in resting platelets and neutrophils, actin is sequestered by T beta 4 as MgATP-G-actin . Kinetic experiments and theoretical calculations demonstrate that this ATP/ADP dependence of T beta 4 affinity for G-actin can generate a mechanism of desequestration of G-actin by ADP, in the presence of physiological concentrations of T beta 4 (approximately 0.1 mM) . The desequestration of G-actin by ADP is kinetically enhanced by profilin, which accelerates the dissociation of ATP from G-actin . Whether a local drop in the ATP/ADP ratio can allow local, transient desequestration and polymerization of actin either close to the plasma membrane, following platelet or neutrophil stimulation, or behind the Listeria bacterium in the host cell, while the surrounding cytoplasm contains sequestered ATP-G-actin, is an open issue raised by the present work. J Infect Dis, 1993 Jun, 167(6), 1364 - 71 Listeria monocytogenes-induced interferon-gamma primes the host for production of tumor necrosis factor and interferon-alpha/beta; Havell EA; Mice acquired an enhanced capacity for the production of tumor necrosis factor (TNF) and the interferons (IFN)-alpha, and -beta shortly after intravenous injection of viable Listeria monocytogenes . By the end of the first day of a sublethal infection, mice were primed to produce 100-1000 times more endotoxin-induced serum TNF than is produced by normal mice . Acquisition of the augmented capacity for TNF production was due to L . monocytogenes-induced IFN-gamma . IFN-gamma also primed infected mice for IFN-alpha/beta production . However, in addition to IFN-gamma, other L . monocytogenes-induced mechanisms endowed the host with an enhanced potential for the production of IFN-alpha/beta . Antibody-mediated depletion of various cell types in vivo revealed that CD8+ cells and NK cells are required for the production of L . monocytogenes-induced IFN-gamma during the first day of listeriosis. Infect Immun, 1993 Jun, 61(6), 2626 - 31 The cellular source of interleukin-6 during Listeria infection; Liu Z et al.; The cellular source of interleukin-6 (IL-6) during infection of mice with Listeria monocytogenes was investigated both in vitro and in vivo . Peritoneal cells taken at intervals from infected mice and cultured in vitro without added stimulus produced high titers of IL-6 peaking 2 days postinfection in a time course similar to that observed in vivo . Adherent cells with the morphology of macrophages were a major source of this IL-6 . Spleen cells similarly harvested at intervals and cultured with heat-killed Listeria or heat-killed Brucella organisms as specific and nonspecific stimuli, respectively, showed two distinct IL-6 responses: (i) an early-phase response up to 5 days after infection when IL-6 production was elicited by either a specific or nonspecific stimulus, and when depletion of T cells had no effect, and (ii) a later response 7 to 10 days after infection when very high levels of IL-6 were produced in response to a specific stimulus . This response was lost when T cells were depleted in vitro or in vivo or in spleen cell cultures from mice with severe combined immunodeficiency . However, studies in vivo failed to show an important role for T cells governing serum IL-6 . We conclude that most of IL-6 detected in vivo is produced by nonlymphocytes . Whether IL-6 produced by T lymphocytes in local foci of infection has any role in resolution of that infection is unknown. Rinsho Shinkeigaku, 1993 Jun, 33(6), 637 - 41 {A case of Listeria rhombencephalitis with a secondary vasculitis suggested by MRI}; Tokonami F et al.; We reported a rare case of Listeria rhombencephalitis with meningitis . A 48-year-old healthy man suddenly experienced high fever and headache, then he had lower cranial nerve's palsies and mental dysfunction developed during one week period . On admission, his temperature was 38 degrees C . He was slightly delirious and euphoric . He had nuchal rigidity, mild paresthesia over his left cheek to left upper lip, a right sixth nerve palsy, dysphagia, hiccup, nasal voice and left cerebellar ataxia . His tongue deviated toward the right side on protrusion . A CSF culture grew Listeria monocytogenes . Intravenous antibiotic therapy (PIPC, minocycline hydrochloride) produced improvement in one month except for mild paresthesia and dysphagia . He almost recovered after 7 months of illness . Brain MRI on T2 weighted image demonstrated multiple small ischemic lesions in the left lateral medulla, upper pontine tegmentum in the right side, and pontine tegmentum in the left side . These lesions enhanced by Gd . were assumed to be due to the secondary vasculitis . Listeria rhombencephalitis is extremely rare in human beings . To our knowledge only thirteen cases have been reported . In seven cases, post-mortem pathological findings confirmed necrotizing angitis in brainstem . Clinical aspects of Listeria rhombencephalitis were discussed, and the entity of this disease should be considered as a treatable cause of acute progressive brainstem meningoencephalitis. J Leukoc Biol, 1993 Jun, 53(6), 651 - 7 Splenic macrophage activation and functions in amyloid enhancing factor-induced secondary amyloidosis . Study of phagocytosis, killing, respiratory burst, and MHC class II surface expression; Reid C et al.; Secondary amyloidosis is a systemic disease characterized by the extracellular tissue deposition of insoluble fibrillar amyloid A protein . Aberrant metabolism of serum amyloid A protein by reticuloendothelial cells is thought to result in the accumulation of fibrils within the tissue . Treatment of mice with amyloid-enhancing factor (AEF) in conjunction with an inflammatory stimulus (i.e., AgNO3) induced amyloid deposition within 48-72 h . The activation state of a macrophage largely defines its enzymatic capabilities . In the studies reported here, we examined the effect of AEF on spleen macrophage activation using both functional and phenotypic assays . We found that while AEF in the presence or absence of AgNO3 has no apparent effect on the ability of spleen and liver macrophages to phagocytose or kill Listeria monocytogenes, it appears to block enhanced respiratory burst function (as measured by O2- production) observed with AgNO3 alone . AEF therefore seems capable of inhibiting certain macrophage activation-associated functions while not affecting others . Our activation phenotype studies, using surface Ia expression, reveal that AEF blocks the increase in number of splenic macrophages expressing Ia seen with AgNO3 alone . Treatment with interferon-gamma was found to restore decreased Ia expression in animals given AEF+AgNO3 but did not prevent amyloid A fibril deposition. Infect Immun, 1993 Jun, 61(6), 2537 - 44 Regulation of the prfA transcriptional activator of Listeria monocytogenes: multiple promoter elements contribute to intracellular growth and cell-to-cell spread; Freitag NE et al.; The prfA gene product is a transcriptional activator of Listeria monocytogenes determinants of pathogenicity . In this study, we provide direct evidence that the PrfA protein is a site-specific DNA-binding protein . Additionally, we describe the characterization of two classes of L . monocytogenes mutants which contain transposon insertions either in the prfA structural gene (exemplified by strain DP-L1075) or within the prfA promoter region (exemplified by strain DP-L973) . Both mutants are completely avirulent and secrete greatly reduced levels of listeriolysin O and phosphatidylinositol-specific phospholipase C, and both are fully complemented by the introduction of prfA on a multicopy plasmid . The behaviors of the two mutants differ markedly within cultured macrophages . Following infection, no cytoplasmic growth was observed for DP-L1075 whereas DP-L973 escaped from the phagosome and grew in the cell cytoplasm . However, DP-L973 was defective in nucleation of actin filaments and spread to adjacent cells . Transcription of prfA in DP-L973 was directed from a single, previously unidentified promoter (prfAp2) located close to the prfA initiation codon . This promoter is therefore capable of providing sufficient prfA expression for escape from the host cell vacuole but is insufficient for wild-type levels of bacterially induced actin polymerization and cell-to-cell spread . Transcription directed from both prfAp1 and prfAp2 promoters was increased in the absence of a functional prfA gene product, suggesting that PrfA protein contributes to down-regulating its own expression. Mol Cell Probes, 1993 Jun, 7(3), 199 - 207 A combined modified reverse dot-blot and nested PCR assay for the specific non-radioactive detection of Listeria monocytogenes; Bsat N et al.; A modified reverse dot-blot assay was developed and used in combination with a nested PCR amplification of hly A for the specific detection of Listeria monocytogenes . The deoxynucleotides and digoxygenin-11-dUTP concentrations in the PCR were optimized for maximal sensitivity and economy . For the dot-blot hybridization, digoxygenin-labelled PCR products were directly spotted on nylon membrane-bound poly-dT tailed capture probes and the signal detection was either colorimetric or chemiluminescent . With crude cell lysates, the total assay could be completed in about 6 h with a detection limit between 2 and 25 colony forming units (cfu) per PCR . The assay was then tested for its applicability to environmental sampling of artificially contaminated aluminum surfaces . For environmental sampling, the assay requires an additional overnight enrichment step and has a sensitivity corresponding to 5 cfu per 25 cm2 of inoculated surface. Clin Invest Med, 1993 Jun, 16(3), 219 - 25 An animal model of foodborne Listeria monocytogenes virulence: effect of alterations in local and systemic immunity on invasive infection; Schlech WF 3rd; Development of foodborne listeriosis is dependent on an interplay between organism-specific virulence factors and host susceptibility . Gastric inoculation of Sprague-Dawley rats was used as a model to explore Listeria-specific virulence and host susceptibility . Gastric inoculation leads to invasive infection with "smooth" hemolytic Listeria monocytogenes but not with "rough" L . monocytogenes or other Listeria species . Infection is dose-dependent with an ID50 of 10(6) virulent Listeria monocytogenes . In these experiments, the ID50 was not altered by pregnancy but invasive infection led to abnormal reproductive outcomes including stillbirth and reabsorption of fetuses . Immunosuppression by cyclosporin A led to more prolonged infection but did not alter the ID50 . Manipulation of intestinal flora with antibiotics suggested increased rates of infection with antibiotics that decreased anaerobic flora . Growth of virulent Listeria in milk at varying temperatures did not enhance virulence . No differences in invasive potential of flagellated vs . non-flagellated L . monocytogenes were found . Oral models of invasive Listeria monocytogenes infection provide a useful tool for studying organism virulence and host susceptibility. Int J Food Microbiol, 1993 Jun 1, 18(4), 289 - 303 Distribution of Listeria spp . in confectioners' pastries from western France: comparison of enrichment methods; Ferron P et al.; Three hundred samples of pastry from 100 different suppliers in western France, including butter-cream, whipped dairy cream and custard filled cakes from each supplier, were collected and tested for the occurrence of Listeria spp . in 25 g samples . Listeria spp . were detected in 21.7% of he samples: Listeria monocytogenes in 13.7%, Listeria innocua in 10% and Listeria seeligeri in 2.3% . Thirteen samples were contaminated with two species simultaneously . The frequency of contaminated samples was not related to the composition of the pastry filling used, but it seemed to increase with the number of aerobic contaminant microorganisms in the dairy cream-based samples . The contamination rate was dependent on the place of manufacture . The numbers of Listeria spp . and Listeria monocytogenes were estimated on positive samples at the 25 g level as follows: < 0.3/g, Listeria spp . in 47 samples, L monocytogenes in 27; 0.3-30/g, Listeria spp . in 13, L . monocytogenes in nine; 30-300/g, L . monocytogenes in one; 300-3000/g; L . monocytogenes in three; 700,000/g, L . monocytogenes in one . Various detection methods were tested, including two enrichments broths tested in parallel: a modified LEB broth using 10 mg/l acriflavine-HCl and the UVM 1 broth, with incubation at 30 degrees C and streaking onto PALCAM agar . The enrichment procedures were: (a) primary enrichment of 25 g sample and plating after 48 h and 7 days; (b) secondary enrichment by subculturing the primary enrichment broths incubated for 24 h and 6 days, into fresh enrichment broth, then plating after 24 h incubation; (c) pre-enrichment of 25 g sample for 24 h in the basal enrichment broths without inhibitors, followed by subculturing in complete broths which were plated after 24 h and 6 days incubation . In all cases, UVM performed better than the LEB broth . It was unnecessary to extend the primary enrichment period beyond 48 h . Secondary enrichments inoculated from 24-h incubated primary enrichments gave a slightly better isolation rate than primary enrichments . Secondary enrichments made from 6-day incubated primary enrichments gave no additional advantage . The pre-enrichment procedure had an efficiency higher than that obtained by primary enrichment. J Clin Microbiol, 1993 Jun, 31(6), 1537 - 40 Kinetics of antibody production against listeriolysin O in sheep with listeriosis; Lhopital S et al.; The kinetics of antibody production against listeriolysin O (LLO), a major virulence factor of the intracellular bacterial pathogen Listeria monocytogenes, was studied by dot blot analysis with highly purified LLO during oral infection of sheep . Specific antibodies appeared as soon as day 9 of an oral infection and peaked by day 20 of infection; specific antibody levels then remained almost stable for at least 4 months . A subclinical infecting dose (approximately 10(6) viable bacteria) was capable of eliciting a significant antibody response to LLO, almost at the same level as that observed with a high-dose oral challenge (approximately 10(10)) . Antibodies to LLO were mostly constituted by immunoglobulin G (IgG), since an IgA response was not detectable and only a transient and inconstant IgM response was observed between day 9 and day 20 of an oral infection . These results show that antibodies to LLO are constantly produced during oral infection even with a low infecting dose, thus confirming that LLO is highly immunogenic . Detection of antibodies to LLO can therefore be used to detect sheep that have been previously exposed to L . monocytogenes. Immunology, 1993 Jun, 79(2), 196 - 202 Increase of Thy-1 antigen on the thymocytes accompanied with their augmented adhesion capacity to thymic epithelial cells in the mice infected with Listeria monocytogenes; Maeda Y et al.; It becomes increasingly clear that adhesion systems such as CD2/LFA-3 (lymphocyte function-associated antigen-3), LFA-1/ICAM-1 (intercellular adhesion molecule-1) and Thy-1/putative Thy-1 ligand participate in the association between murine thymocytes and thymic epithelial cells . In the present study, thymocytes showed an increase in surface Thy-1 levels in mice infected with Listeria monocytogenes, but no significant changes in the levels of CD2 or LFA-1 . No alteration was found either in the ratio of CD3high/CD3low/CD3- or in that of CD4/CD8 subsets in these thymocytes compared with uninfected control thymocytes which excluded the possibility of enrichment of 'cortical thymocytes' with Thy-1high/CD3low/CD4+ CD8+ in the thymocyte population of infected mice . Moreover such Thy-1high thymocytes exhibited a highly augmented ability of adhesion to a thymic epithelial cell line due to the increase of surface Thy-1 antigens as an adhesion molecule . At such intervals after infection, the total number of thymocytes was found to be reduced . These results suggest that the expression level of surface Thy-1 on thymocytes is regulated in response to in vivo stimulation and may play a role in the intrathymic development of thymocytes by affecting the adhesion of thymocytes with thymic stromal cells . The implication of the enhanced ability of adhesion in the decrease in the number of thymocytes is discussed. Infect Immun, 1993 Jun, 61(6), 2703 - 7 Leukocyte-mediated lysis of infected hepatocytes during listeriosis occurs in mice depleted of NK cells or CD4+ CD8+ Thy1.2+ T cells; Conlan JW et al.; An important early component of defense against listeriosis in mice is the lysis of infected hepatocytes by leukocytes that accumulate at foci of infection in the liver . This serves to release Listeria monocytogenes from permissive parenchymal cells for ingestion and inactivation by phagocytic cells . It is shown here that lysis of infected hepatocytes is as extensive in mice depleted of T cells or NK cells as it is in control mice . This supports the original interpretation that hepatocyte lysis is mediated mainly by neutrophils. Clin Exp Immunol, 1993 Jun, 92(3), 473 - 6 Failure of FK 506 to suppress the T cell-mediated immunity of mice to Listeria monocytogenes; Wagner JA et al.; Listeria monocytogenes belongs to the group of intracellular bacteria, which means that they reside and multiply within host cells . The protective immunity against such an infection is mediated by cellular immune mechanisms . Whereas the CD8+ T cell population plays a major role therein, the CD4+ T cells are held to be of minor importance in this defence system . Consequently, one can understand that immune suppression with FK 506 which acts primarily on this latter T cell subset, does not interfere with protective immunity of mice infected with L . monocytogenes . We have demonstrated that the drug blocks neither curing of primary infection, nor formation of granulomas, nor induction of cell populations capable of mediating adoptive transfer of immunity, nor expression of pre-existing immunity. Appl Environ Microbiol, 1993 May, 59(5), 1289 - 93 Detection of Listeria monocytogenes in cheese with the magnetic immuno-polymerase chain reaction assay; Fluit AC et al.; A new detection system, the magnetic immuno-polymerase chain reaction (PCR) assay (MIPA) has been developed to detect Listeria monocytogenes in food . This method separates Listeria cells from PCR-inhibitory factors present in enrichment broths containing food samples by using magnetic beads coated with specific monoclonal antibodies (MAbs) . The separated bacteria were lysed, and the supernatant containing the bacterial DNA was subjected to the PCR . Detection of L . monocytogenes in three naturally contaminated cheese samples with two different MAbs and PCR primers specific for the gene encoding the delayed-hypersensitivity factor showed that with MAb 55 all three samples were positive whereas with MAb A two samples were positive . A further improvement of the method was obtained by using a PCR step based on the listeriolysin O gene . A MIPA employing MAb 55 and the listeriolysin O gene primer set detected L . monocytogenes after 24 h of culture in Listeria Enrichment Broth samples from Port Salut artificially contaminated with 40 CFU/25 g . We could detect 1 CFU of L . monocytogenes per g of cheese after a second enrichment for 24 h in Fraser broth . The analysis time including both enrichments is approximately 55 h. Immunology, 1993 May, 79(1), 82 - 8 Murine complement receptor gene expression: Cr2 gene transcripts are depressed during a high dose microbial challenge; Tan SS et al.; The murine Cr2 gene encodes mRNA that produce two protein products predicted to be approximately 145,000 M(r) (Cr2-145) and 190,000 M(r) (Cr2-190) . All cells examined which express the Cr2 gene produce transcripts encoding both the Cr2-145 and Cr2-190 proteins: both transcripts are constitutively expressed by mature B cells . To determine if Cr2 expression could be altered by activating splenic B cells, splenic cultures were incubated with lipopolysaccharide (LPS) and cell surface Ig chains were cross-linked with anti-mu . In the presence of LPS and anti-mu both Cr2 and Oct-2 transcripts were diminished while the control beta-actin transcript levels remained unchanged . However, when LPS alone was added, only the Cr2 transcript levels were diminished . To test if these findings could be reproduced in vivo, animals were provided with a peritoneal injection of either Escherichia coli or Listeria monocytogenes and transcript levels analysed . The quantities of both Cr2 transcripts, as well as those encoding Oct-2, were substantially reduced in splenocytes and peripheral lymphatic tissues obtained from these infected mice while those encoding the mouse Crry protein, the B-cell marker CD19 and beta-actin remained unchanged . These data suggest that when confronted with a major bacterial infection, murine B cells respond by shutting down synthesis of transcripts encoding the Cr2 and Oct-2 gene products. Clin Infect Dis, 1993 May, 16(5), 689 - 702 Brainstem encephalitis (rhombencephalitis) due to Listeria monocytogenes: case report and review; Armstrong RW et al.; Listerial brainstem encephalitis is a rare disease . Only 62 cases have been reported previously; all were in adults, only 8% of whom were immunosuppressed . The disease has a characteristic biphasic course: a nonspecific prodrome of headache, nausea or vomiting, and fever lasting for several days is followed by progressive asymmetrical cranial-nerve palsies, cerebellar signs, hemiparesis or hypesthesia, and impairment of consciousness . Neck stiffness was initially present in only 55% of the cases described thus far . Studies of cerebrospinal fluid often revealed only mild abnormalities . Cultures of cerebrospinal fluid and blood were positive in 41% and 61% of cases, respectively . Respiratory failure occurred in 41% of cases . Initial computed tomography of the brain often gave normal results; magnetic resonance imaging better demonstrated brainstem abnormalities . Overall mortality was 51% . All untreated patients died . When treatment with ampicillin or penicillin was initiated early, the rate of survival was > 70%; however, neurological sequelae developed in 61% of survivors. J Infect, 1993 May, 26(3), 301 - 3 Neonatal cross-infection with Listeria monocytogenes; Pejaver RK et al.; Transmission of Listeria monocytogenes by food continues to cause concern . Even so, this is not the only means of transmission and neonatal hospital-acquired infection has been well recorded . We report here two cases of perinatal listeriosis one of which was likely to have been due to cross-contamination in a Special Care Baby Unit (SCBU) with equipment acting as the vehicle. J Leukoc Biol, 1993 May, 53(5), 525 - 31 Cytokine mRNA expression in livers of mice infected with Listeria monocytogenes; Wagner RD et al.; Temporally distinct groups of cytokine expression was observed by reverse transcription-polymerase chain reaction assay, in situ hybridization, and immunohistochemistry in the livers of Listeria monocytogenes-infected mice . One group consisted of interferon-gamma (IFN-gamma), tumor necrosis factor alpha (TNF-alpha), and interleukin-10 (IL-10), for which mRNAs were induced within 1 day after challenge . A second group consisted of IL-2 and IL-4, for which mRNA was strongly expressed at 1 day but then suppressed at 3 days into the infection . Granulocyte-macrophage colony-stimulating factor (GM-CSF), IL-1 alpha, and IL-6 mRNA constituted a third group, which was increased at 3 days after challenge . Distributions of cytokine mRNA-expressing cells in the liver was observed by in situ hybridization . Cells expressing TNF-alpha and IL-1 alpha mRNA were present throughout liver granulomas, whereas cells that expressed IFN-gamma mRNA were observed mostly along the periphery of granulomas . Cells expressing IL-2, IL-4, IL-6, IL-10, and GM-CSF mRNA were distributed principally in the hepatic sinuses . Cells expressing IL-10 mRNA increased in number early in the infection when L . monocytogenes was multiplying in the liver . We conclude that cytokine mRNA expression during the early phases of L . monocytogenes infection in mice is temporally regulated and that IFN-gamma, TNF-alpha, and IL-1 alpha are expressed by cells associated with hepatic granulomas. Int J Food Microbiol, 1993 May, 18(3), 223 - 32 Fate of Listeria monocytogenes in raw and cooked ground beef with meat processing additives; Harmayani E et al.; The effect of sodium lactate (1.8% w/w), sodium erythorbate (0.1% w/w), kappa-carrageenan (1% w/w), and the alginate meat binder (0.4% w/w, sodium alginate; 0.6% w/w lactic acid; and 0.075% w/w calcium carbonate) on Listeria monocytogenes survival and growth was determined in raw and cooked ground beef stored aerobically at 4 degrees C . There was no significant (P > 0.05) increase in numbers of L . monocytogenes during storage of raw ground beef . However, L . monocytogenes numbers were generally lower in treatments with sodium lactate, and higher in sodium erythorbate compared to controls and meat with other additives . Increases in total aerobic plate counts were less pronounced in raw meat formulated with sodium lactate and alginate meat binder than with other additives . Cooking meat with initial inoculum levels of 6.52 to 7.03 L . monocytogenes log CFU/g to 65 degrees C resulted in lower destruction (0.56 and 1.18 log CFU/g) in samples with added alginate meat binder and kappa-carrageenan, respectively, compared to the control . Survivors (2.11-3.73 log CFU/g) decreased initially and then increased slightly, but not significantly (P > 0.05), during storage (4 degrees C, 6 days) of the cooked products. J Med Microbiol, 1993 May, 38(5), 322 - 7 Typing of Listeria spp . by random amplified polymorphic DNA (RAPD) analysis; MacGowan AP et al.; Random amplified polymorphic DNA (RAPD) analysis, a variation of the polymerase chain reaction (PCR) in which a single primer is used, was evaluated for use as a simple and reliable method with which to type Listeria spp . Representatives of six species of Listeria were studied . Five isolates of L . innocua and four isolates of L . seeligeri were all distinguishable from one another, but the four isolates of L . ivanovii tested, although distinguishable from other Listeria spp., were not differentiated . Among L . monocytogenes serovars 1/2a (eight isolates), 1/2b (eight isolates) and 4b (10 isolates), at least six, three and six RAPD patterns were observed, respectively . Fourteen neonatal cross-infection sets of L . monocytogenes isolates, shown to be indistinguishable by serotyping and phage typing, were examined with three different primers . With one primer, three of the sets were shown to consist of closely related, but distinguishable, strains . In the other 11 cases, each set of strains was indistinguishable with all three primers . These preliminary data indicate that RAPD analysis has promise as a method for typing Listeria spp. J Appl Bacteriol, 1993 May, 74(5), 515 - 20 Acetic, lactic and citric acids and pH inhibition of Listeria monocytogenes Scott A and the effect on intracellular pH; Young KM et al.; The effects of acetic, lactic and citric acids and pH on the growth and intracellular pH (pHin) of Listeria monocytogenes Scott A were documented and compared for total acid concentrations ranging from 50 mmol ml-1 to 250 mmol ml-1 for acetic and lactic acids and from 25 mmol ml-1 to 100 mmol ml-1 for citric acid . Initial pH values ranged from 4.7 to 6.0 . Although the growth rate of L . monocytogenes Scott A was slower when incubated at 25 degrees C than at 37 degrees C, the relative acid and pH inhibition was identical at both temperatures . As the initial pH values decreased and/or the total acid concentrations increased, the growth rates of L . monocytogenes Scott A decreased . Compared at equal initial pH values and on an equimolar total acid basis, the relative inhibition effect was generally acetic > lactic > citric . When based on initial undissociated acid concentrations, the inhibition effect was citric > lactic > acetic . The effect of differing acid and pH environments on pHin was determined . At equimolar total acid concentrations, the pHin of the cell was changed the least by citric acid and the most by acetic acid . Growth rates were influenced by the pHin and the acid used to adjust the system. Infect Immun, 1993 May, 61(5), 2245 - 8 Characterization of an aromatic amino acid-dependent Listeria monocytogenes mutant: attenuation, persistence, and ability to induce protective immunity in mice; Alexander JE et al.; A transposon insertion mutant of Listeria monocytogenes was shown to be deficient in prephenate dehydratase, an enzyme acting late in the pathway for biosynthesis of phenylalanine . This mutant had reduced virulence in mice . The mutant and parent strains persisted to the same extent in the tissues of infected mice and elicited similar degrees of splenomegaly . Mice vaccinated with the mutant were protected significantly from subsequent challenge with virulent L . monocytogenes. Infect Immun, 1993 May, 61(5), 2154 - 61 Listeria monocytogenes-induced gamma interferon secretion by intestinal intraepithelial gamma/delta T lymphocytes; Yamamoto S et al.; gamma/delta T cells represent a major proportion of intestinal intraepithelial lymphocytes (IEL), and it has been suggested that these IEL serve as a first immune barrier against microbial invasion and that they do so by destroying infected epithelial cells . In the present study, we confirm that both alpha/beta and gamma/delta IEL from naive mice express potent cytotoxicity and produce gamma interferon (IFN-gamma) after T-cell receptor (TCR) engagement by specific monoclonal antibodies (MAb) . Intraperitoneal administration of the anti-gamma/delta TCR MAb GL3 caused downregulation of the gamma/delta TCR in IEL, and IEL from gamma/delta TCR-modulated mice failed to express cytotoxic activity and to secrete IFN-gamma after gamma/delta TCR engagement . In contrast, alpha/beta IEL from such mice were still cytolytic and secreted IFN-gamma . Mice were infected orally with virulent Listeria monocytogenes at doses which caused bacterial invasion through the intestinal epithelia . Although alpha/beta and gamma/delta IEL from these mice expressed high cytolytic activities in antibody-redirected killer assays, target cells pulsed with listerial antigens were not lysed . In contrast, IFN-gamma secretion by IEL from L . monocytogenes-infected mice was induced not only by anti-TCR MAb but also by target cells pulsed with listerial antigens, whereas irrelevant antigens, including heat shock protein 60, did not induce IFN-gamma secretion . Furthermore, the number of IFN-gamma-secreting IEL, as assessed by the enzyme-linked immunospot technique, was increased during listeriosis . gamma/delta TCR modulation by GL3 administration abrogated antigen-induced IFN-gamma secretion by IEL from infected mice . These findings suggest that L . monocytogenes induced IFN-gamma secretion by gamma/delta IEL from mice suffering from intestinal L . monocytogenes infection and invasion . Thus, the data provide evidence for a role of IFN-gamma-secreting IEL in local resistance against listeriosis and perhaps other food-borne diseases. AJR Am J Roentgenol, 1993 May, 160(5), 1089 - 93 Mesenrhombencephalitis: MR findings in nine patients; Soo MS et al.; OBJECTIVE . Mesenrhombencephalitis is a serious form of brainstem inflammation predominantly involving the deep and vital portions of the brain, that is, the mesencephalon (midbrain) and rhombencephalon (pons, medulla) . Mesenrhombencephalitis is difficult to diagnose on the basis of clinical and laboratory findings alone, and access to this portion of the brain for surgical biopsy carries high morbidity . We describe the MR appearance of mesenrhombencephalitis and correlate the imaging findings with clinical information . MATERIALS AND METHODS . Unenhanced and contrast-enhanced MR images of nine patients with mesenrhombencephalitis were reviewed retrospectively and correlated with clinical, laboratory, and pathologic data . The patients were categorized according to the cause of the disease: three had herpes simplex, one had Listeria monocytogenes, and five had mesenrhombencephalitis of undetermined cause . The three patients with clinical and MR evidence of herpes simplex mesenrhombencephalitis (one confirmed by brain biopsy) were comatose at presentation, with cranial nerve abnormalities in two and seizures in one . One patient with L . monocytogenes (established by blood culture) had cranial nerve palsies, fever, and pain in the ear . Five additional patients had headache (three), fever (three), nausea and vomiting (four), cranial nerve palsies (three), coma (two), and hyporeflexia (one) or hyperreflexia (four) . Brain biopsy performed in two patients revealed chronic inflammation of unspecified cause; in one, it was compatible with viral encephalitis . RESULTS . MR images in three patients with herpes simplex mesenrhombencephalitis showed T2 signal hyperintensity in the midbrain (two), pons (one), medulla (one), and temporal lobes (three) . Parenchymal foci of hemorrhage (methemoglobin, one patient) and leptomeningeal enhancement (one patient) were identified in the temporal lobes . T2-weighted MR images in one patient with L . monocytogenes showed signal hyperintensity in the brainstem, vermis, midbrain, and internal capsules . On T1-weighted images, low signal was present in these areas, which enhanced with paramagnetic contrast agents . In the remaining five patients, T2-weighted MR images showed patchy signal hyperintensity in the pons, medulla, and thalamus in three each and in the midbrain and temporal lobes in one each . T1-weighted MR images showed normal findings (two) or signal hypointensity in the thalamus and pons in one patient each . Areas of leptomeningeal and parenchymal enhancement were identified in one patient each . Brainstem swelling was seen in three patients, one of whom had petechial hemorrhage in the pons and hydrocephalus . CONCLUSION . Mesenrhombencephalitis is a serious illness that is diagnosed by a combination of imaging, clinical, laboratory, and pathologic studies . MR imaging may be crucial to the early diagnosis of this illness, and radiologists must be familiar with this uncommon entity and its MR findings in order to make timely diagnoses and facilitate treatment. Med Microbiol Immunol (Berl), 1993 May, 182(2), 87 - 95 Purification and characterization of a 58-kDa cell wall-associated protein from Listeria monocytogenes; Belyi YF et al.; A cell wall protein (P58) was purified from Listeria monocytogenes by detergent extraction and Superose 6 gel chromatography . It had a molecular mass of 58 kDa, was strongly hydrophobic, contained reactive thiol group(s) and was located at least partially on the surface of bacterial cells . Production of this protein varied among different Listeria, being the most prominent in NCTC 7973 of L . monocytogenes, weaker in four other strains of this species and undetectable in tested strains of L . seeligeri and L . innocua . Mice that survived experimental listerial infection produced antibodies against P58 . This fact allowed us to speculate that the described protein can be used as a marker for sero-diagnosing of listeriosis. Mol Microbiol, 1993 May, 8(4), 653 - 61 Expression of listeriolysin and phosphatidylinositol-specific phospholipase C is repressed by the plant-derived molecule cellobiose in Listeria monocytogenes; Park SF et al.; The primary habitat of the intracellular pathogen Listeria monocytogenes is considered to be soil and decaying vegetation . As an opportunistic pathogen it must be able to recognize its entry into host tissue and, in response, co-ordinately induce the expression of virulence factors . No signature molecule, which facilitates this regulation, has been identified for any human pathogen . Our studies have demonstrated for the first time that the expression of major virulence determinants in L . monocytogenes can be repressed by an environmentally ubiquitous molecule . Transcriptional hlyA and plcA fusions to luxAB were used to monitor virulent gene expression in the presence of various disaccharides . These studies revealed that the expression of listeriolysin O and phosphatidylinositol-specific phospholipase C is repressed specifically by the plant-derived disaccharide, cellobiose. Res Microbiol, 1993 May, 144(4), 279 - 83 Dependence of fatty acid composition of Listeria spp . on growth temperature; Puttmann M et al.; In Listeria spp., various fatty acids are produced; by far the most common members are C15 and C17 chain length fatty acids . This pattern is rather similar in all species . At low temperatures, most of the Listeria are able to change the relative composition whereby more of the C15 fatty acids are produced, which could increase the fluidity of the bacterial cell membrane under these conditions. Science, 1993 Apr 23, 260(5107), 547 - 9 Development of TH1 CD4+ T cells through IL-12 produced by Listeria-induced macrophages; Hsieh CS et al.; Development of the appropriate CD4+ T helper (TH) subset during an immune response is important for disease resolution . With the use of naive, ovalbumin-specific alpha beta T cell receptor transgenic T cell, it was found that heat-killed Listeria monocytogenes induced TH1 development in vitro through macrophage production of interleukin-12 (IL-12) . Moreover, inhibition of macrophage production of IL-12 may explain the ability of IL-10 to suppress TH1 development . Murine immune responses to L . monocytogenes in vivo are of the appropriate TH1 phenotype . Therefore, this regulatory pathway may have evolved to enable innate immune cells, through interactions with microbial pathogens, to direct development of specific immunity toward the appropriate TH phenotype. FEMS Microbiol Lett, 1993 Apr 15, 108(3), 311 - 8 Utilization of transferrin-bound iron by Listeria monocytogenes; Hartford T et al.; It has been demonstrated that under iron-restricted conditions, Listeria monocytogenes can utilize iron-loaded transferrin (Tf) from a range of species as its sole source of iron for growth . Human transferrin conjugated to horseradish-peroxidase (HRP-Tf) bound directly to whole cells of L . monocytogenes . This binding was blocked by apotransferrin indicating that the receptor can bind transferrin in either the iron-bound or iron-free form . Transferrin-binding was not host specific because both bovine and equine transferrin inhibited the binding of HRP-conjugated human transferrin . SDS-PAGE and Western blotting of bacterial surface extracts revealed the presence of a transferrin-binding protein of approximately 126 kDa. Proc Natl Acad Sci U S A, 1993 Apr 15, 90(8), 3725 - 9 Interleukin 12 and tumor necrosis factor alpha are costimulators of interferon gamma production by natural killer cells in severe combined immunodeficiency mice with listeriosis, and interleukin 10 is a physiologic antagonist; Tripp CS et al.; Listeriosis in mice with the severe combined immunodeficiency (SCID) mutation is an established model in vivo and in vitro of interferon gamma (IFN-gamma)-dependent macrophage activation by natural killer (NK) cells during the development of natural immunity . We demonstrate that IFN-gamma production from SCID splenocytes is stimulated by interleukin (IL) 12, tumor necrosis factor alpha (TNF-alpha), and IL-2 but is inhibited by IL-10, IL-10, IL-12, and TNF are induced by heat-killed Listeria monocytogenes (