Comparative safety and efficacy against Bacillus anthracis of protective antigen and live vaccines in mice.
The efficacy and mechanisms of protection of two live vaccines and of a protective antigen (PA) vaccine against Bacillus anthracis were studied in inbred mice. Mice that differed in their natural resistance to killing by Sterne, a non-encapsulated, toxigenic vaccine strain of B. anthracis, were used. Vaccination with live Sterne spores protected Sterne-resistant mice against challenge with the virulent Vollum 1B (V1B) strain of B. anthracis, but only at doses of Sterne greater than or equal to 0.1 50% lethal dose. The live B. subtilis recombinant strain PA2, which produces the PA component of anthrax toxin, fully protected (CBA/J) or partially protected (BALB/cJ) Sterne-resistant mice against V1B. Neither immunization with the cell-free PA vaccine nor passive administration of anti-PA antiserum protected Sterne-resistant mice against V1B. Sterne-susceptible A/J mice were not protected against V1B by either live vaccine or by the PA vaccine. However, immunization with strain PA2 induced anti-PA antibody and protected A/J mice against Sterne. A/J mice passively treated with antitoxin antibodies also survived Sterne, and survivors were then partially protected against V1B. Thus, immunity to Sterne correlated with an effective anti-PA response. Immunity to fully virulent V1B also required PA but may involve mechanisms in addition to humoral immunity.
Welkos
S L
SL
Bacteriology Division, U.S. Army Medical Research Institute of Infectious Diseases, Frederick, MD 21701-5011.
Friedlander
A M
AM
D000818:Animals; D000942:Antigens, Bacterial / Q000276:immunology*; D000992:Antitoxins / Q000276:immunology; D001408:Bacillus anthracis / Q000276:immunology*; D001412:Bacillus subtilis / Q000235:genetics; D001427:Bacterial Toxins / Q000276:immunology; D001428:Bacterial Vaccines / Q000633:toxicity; D007114:Immunization; D007116:Immunization, Passive; D051379:Mice; D008815:Mice, Inbred Strains; D011995:Recombination, Genetic; D013171:Spores, Bacterial / Q000276:immunology; D014613:Vaccines, Attenuated / Q000276:immunology
D000942:Antigens, Bacterial; D000992:Antitoxins; D001427:Bacterial Toxins; D001428:Bacterial Vaccines; D014613:Vaccines, Attenuated; C030325:anthrax toxin