title: Intracellular growth of Listeria monocytogenes insertional mutant deprived of protein p60.
abstract: The study of the mutant strain described here demonstrates that several characteristics contribute to maximal virulence of pathogenic strains of L. monocytogenes. The invasion levels of L. monocytogenes JB1115, a p60-deficient strain, were the same as for the parent strain L. monocytogenes 1043S in J774 macrophage-like cells. The invasion level of Listeria strains in Int407 cells was 100 times lower than in J774 cells. In epithelial Int407 cells, the time of division of p60- strain L. monocytogenes JB1115 was 43% slower than for the parent strain. In this study, two lisosomotrophic agents, ammonium chloride and chlorquinoline were tested in experimental L. monocytogenes 1043S and p60-deprived mutant JB1115 infection in both cell lines. The presence of ammonium chloride increased the level of infection (calculated as number of gentamicin-resistant cells) of both Listeria strains, but in the case of infection by p60 mutant, the increased amount of ammonium chloride showed only a minimal effect on the number of isolated bacteria. In both cell lines treated with chlorquinoline we observed a decrease in the number of viable intracellular bacteria isolated from infected monolayers. Our observation of parental and mutated strains of Listeria showed that phospholipase activity also depends on the presence of p60 protein. Mutated strain showed 31.46% reduction of PI-PLC activity measured in normal growth conditions. Protein p60 plays a role not only in listeriolysin O mediated haemolytic activity but full phospholipase C activity is also dependent on the presence of the Iap protein.
authors.affiliation: Institute of Microbiology, Warsaw University, Poland.
authors.forename: J M
authors.initials: JM
authors.lastname: Wiśniewski
authors.forename: J E
authors.initials: JE
authors.lastname: Bielecki
mesh_terms: D000643:Ammonium Chloride / Q000494:pharmacology; D000818:Animals; D001426:Bacterial Proteins / Q000235:genetics / Q000502:physiology*; D001427:Bacterial Toxins; D002460:Cell Line; D006360:Heat-Shock Proteins / Q000378:metabolism; D006460:Hemolysin Proteins; D006863:Hydrogen-Ion Concentration; D007413:Intestinal Mucosa / Q000382:microbiology; D008089:Listeria monocytogenes / Q000235:genetics / Q000254:growth & development* / Q000472:pathogenicity*; D008264:Macrophages / Q000382:microbiology; D051379:Mice; D016254:Mutagenesis, Insertional; D010738:Type C Phospholipases / Q000378:metabolism; D014617:Vacuoles / Q000378:metabolism / Q000382:microbiology; D014774:Virulence
chemical_list: C078516:60 kDa protein, Listeria monocytogenes; D001426:Bacterial Proteins; D001427:Bacterial Toxins; D006360:Heat-Shock Proteins; D006460:Hemolysin Proteins; D000643:Ammonium Chloride; D010738:Type C Phospholipases; C038705:hlyA protein, Listeria monocytogenes