Immunization with recombinant Brucella spp. outer membrane proteins Omp16 or Omp19 in adjuvant induces specific CD4+ and CD8+ T cells as well as systemic and oral protection against Brucella abortus infection.

PASQUEVICH K. A., ESTEIN S. M., GARCÍA SAMMARTINO C., ZWERDLING A, CORIA L., BARRIONUEVO P., FOSSATI C.A., GIAMBARTOLOMEI1 G. H., CASSATARO J.

INFECTION AND IMMUNITY

Amercan Society of Microbiology

Lugar: Washington D.C., USA.; Año: 2009 vol. 77 p. 436 - 445

0019-9567

Available vaccines against Brucella spp. are live attenuated Brucella strains. In order to engineer a betterv vaccine to be used in animals and humans, our laboratory aims to develop an innocuous subunit vaccine. Particularly, we are interested in the outer membrane proteins (OMPs) of B. abortus: Omp16 and Omp19. In this study, we assessed the use of these proteins as vaccines against Brucella in BALB/c mice. Immunization with lipidated Omp16 (L-Omp16) or L-Omp19 in incomplete Freund’s adjuvant (IFA) conferred significant protection against B. abortus infection. Vaccination with unlipidated Omp16 (U-Omp16) or U-Omp19 in IFA induced a higher degree of protection than the respective lipidated versions. Moreover, the level of protectioninduced after U-Omp16 or U-Omp19 immunization in IFA was similar to that elicited by live B. abortus S19 immunization. Flow cytometric analysis showed that immunization with U-Omp16 or U-Omp19 induced antigen-specific CD4 as well as CD8 T cells producing gamma interferon. In vivo depletion of CD4 or CD8 T cells in mice immunized with U-Omp16 or U-Omp19 plus IFA resulted in a loss of the elicited  protection, indicating that both cell types are mediating immune protection. U-Omp16 or U-Omp19 vaccination induced a T helper 1 response, systemic protection in aluminum hydroxide formulation, and oral protection with cholera toxin adjuvant against B. abortus infection. Both immunization routes exhibited a similar degree of protection to attenuated Brucella vaccines (S19 and RB51, respectively). Overall these results indicate that U-Omp16 or U-Omp19 would be a useful candidate for a subunit vaccine against human and animal brucellosis.