HUMORAL IMMUNITY TO AEROSOLIZED STAPHYLOCOCCAL-ENTEROTOXIN-B (SEB), ASUPERANTIGEN, IN MONKEYS VACCINATED WITH SEB TOXOID-CONTAINING MICROSPHERES

Staphylococcal enterotoxin B (SEB) toxoid containing microspheres were tested for efficacy;cy in rhesus monkeys as a vaccine candidate for r espiratory SEB toxicosis and toxic shock. Forty monkeys were randomly separated into 10 groups of four monkeys each: 9 groups were vaccinate d with the microspheres via combinations of mucosal and nonmucosal rou tes, and 1 group Served as nonvaccinated controls. Both vaccinated and nonvaccinated monkeys were then challenged with a high lethal dose of SEB aerosol. Monkeys primed with an intramuscular dose of the microsp heres followed by an intratracheal booster all survived the SEB challe nge. Overall, monkeys with an intratracheal booster generally had the highest antibody levels, which is consistent with their high survival rate and lower rate of illness. Protective immunity was correlated wit h antibody levels in both the circulation and the respiratory tract, T he protection was not due to the depletion or anergy of SEB-reactive T cells, since SEB-induced proliferation in cultures of circulating lym phocytes was not significantly reduced after the microsphere vaccinati on. It is evident that the nonsurvivors did not die of systemic anaphy laxis or hypersensitivity because the monkeys did not die immediately after SEB challenge and there were no significant differences in hista mine levels between the vaccinated and control monkeys before and afte r SEB challenge. The antibodies seemed to neutralize the SEB that got into the airway and the circulation.