Bovine Trichomoniasis as a Model for Development of Vaccines against Sexually-transmitted Disease

PROBLEM: Human sexually transmitted diseases (STDs) are widespread but effective vaccines are rare. Experimental and commercially available vaccines for bovine trichomoniasis have been well studied. Principles for immune protection of the female genital tract derived from studies of bovine trichomoniasis may be generally applicable to human trichomoniasis and other STDs. METHOD OF STUDY: A bovine model of trichomoniasis has been developed for study of mechanisms of immunoprophylaxis. RESULTS: Both systemic and local immunization with an immunoaffinity purified antigen cleared the genital tract of trichomonads significantly earlier than non-immunized controls. Predominantly IgA responses or predominantly IgG responses in uterine and vaginal secretions were essentially equally protective. Uterine and vaginal IgA responses could be induced by systemic priming and local boosting via either the vaginal or nasal mucosa. In either case, lymphoid aggregates were formed in the uterine and vaginal mucosa which were not present in the genital mucosa of naive animals. CONCLUSIONS: Systemic immunization or systemic priming with local boosting protects against bovine trichomoniasis via IgG or IgA antibodies (respectively) to a major surface antigen of trichomonads. Immunization of the genital mucosa results in formation of inductive sites for a local IgA response.