ABSTRACT
BACKGROUND: Francisella tularensis, the causative agent of tularemia, is a highly virulent microbe. One significant virulence factor of F. tularensis is the O-polysaccharide (O-PS) portion of the organism's lipopolysaccharide. METHODS: A wzy (O-antigen polymerase) deletion mutant of Ft. live attenuated vaccine strain (Ft.LVS), designated Ft.LVS::Δwzy, was created and evaluated as a live attenuated vaccine. Specifically, the mutant's virulence potential and its protective efficacy against type A and type B strains were investigated by challenge of immunized mice. RESULTS: F. tularensis LVS::Δwzy expressed only 1 repeating unit of O-PS and yet, upon immunization, induced O-PS-specific antibodies. Compared with Ft.LVS, the mutant was highly sensitive to complement-mediated lysis, significantly attenuated in virulence, and was recovered in much lower numbers from the organs of infected mice. Intranasal immunization with Ft.LVS::Δwzy provided protection against subsequent intranasal infection with the highly virulent type A strain SchuS4 and with Ft.LVS. Immunization with Ft.LVS::Δwzy elicited both humoral and cell-mediated immunity. CONCLUSIONS: Ft.LVS::Δwzy was avirulent in mice and, despite expressing only 1 repeating unit of the O-PS, induced antibodies to the full-length O-PS. Vaccination with Ft.LVS::Δwzy protected mice against intranasal challenge with both type A and type B strains of F. tularensis and induced functional immunity through both humoral and cellular mechanisms.
Subject(s)
Bacterial Vaccines/immunology , Francisella tularensis/genetics , Francisella tularensis/pathogenicity , O Antigens/genetics , O Antigens/metabolism , Virulence Factors/genetics , Virulence Factors/metabolism , Animal Structures/microbiology , Animals , Antibodies, Bacterial/blood , Bacterial Load , Bacterial Vaccines/genetics , Disease Models, Animal , Leukocytes, Mononuclear/immunology , Male , Mice , Mice, Inbred BALB C , Tularemia/prevention & control , Vaccines, Attenuated/genetics , Vaccines, Attenuated/immunologyABSTRACT
The present study compares the efficacy of various disinfectants against Bacillus anthracis spores. While Bleach Rite(®) and 10% bleach reduce spore numbers by 90% within 10 minutes, a long contact time is required for complete disinfection. By contrast, although SporGon(®) did not initially reduce the number of spores as quickly as Bleach Rite or 10% bleach, shorter contact times were required for complete eradication of viable spores.
