title: Vaccination against Listeria infection in mice with a mutant strain of reduced virulence.
abstract: Killed Listeria monocytogenes (L.m.) or living Listeria innocua, being unable to afford noticeable immunity against L.m. challenge in mice, the efficacy of a living strain of L.m. of reduced virulence was studied. This strain was obtained from a field strain of low virulence by successive mutations for streptomycin dependence, reversion to independence and resistance to erythromycin. Its protective immunity was checked in mice against IV, SC and intra-gastric challenges. Vaccinated mice were protected against a IV challenge, lethal for controls, and they were rid of infection in a much shorter time than controls after SC or intra-gastric challenges. They were also protected against abortion when the challenge was done by SC, but not by IV route. The level of immunity was shown to be dose-dependent. Appearing very early after vaccination, immunity remained stable for at least four months, then decreased slowly afterwards, but could be restored and even enhanced by a recall. The protection was equally effective against L.m. serovars 1 or 4 challenges.
mesh_terms: D000818:Animals; D001428:Bacterial Vaccines / Q000276:immunology; D004352:Drug Resistance, Microbial; D004917:Erythromycin / Q000494:pharmacology; D005260:Female; D008087:Listeria / Q000187:drug effects / Q000276:immunology / Q000472:pathogenicity*; D008089:Listeria monocytogenes / Q000187:drug effects / Q000276:immunology / Q000472:pathogenicity; D008088:Listeriosis / Q000517:prevention & control*; D008297:Male; D051379:Mice; D009154:Mutation; D011247:Pregnancy; D014774:Virulence
chemical_list: D001428:Bacterial Vaccines; D004917:Erythromycin