The protein moiety of Brucella abortus outer membrane protein Omp16 is a new bacterial pathogen associated molecular pattern that activates dendritic cells in vivo, induces a Th1 immune response and is a promising self-adjuvanting vaccine against systemic

PASQUEVICH K. A., GARCÍA SAMARTINO C., CORIA M. L., ESTEIN S. M., ZWERDLING A., IBÁÑEZ A. E., BARRIONUEVO P., SOUZA DE OLIVEIRA F., CARVALHO N. B., BORKOWSKI J., OLIVEIRA S. C., WARZECHA H., GIAMBARTOLOMEI G. H., CASSATARO J

JOURNAL OF IMMUNOLOGY

AMER ASSOC IMMUNOLOGISTS

Año: 2010 vol. 184 p. 5200 - 5212

0022-1767

Knowing the inherent stimulatory properties of the lipid moiety of bacterial lipoproteins, we first hypothesized that Brucella abortus Omp16 lipoprotein would be able to elicit a protective immune response without the need of external adjuvants. In this study we demonstrate that Omp16 administered by the i.p. route confers significant protection against B. abortus infection and the protective response evocated is independent of the protein lipidation. To date, Omp16 is the first Brucella protein that without the requirement of external adjuvants is able to induce similar protection levels to the control live vaccine S19. Moreover, the protein portion of Omp16 (U-Omp16) elicits a protective response when is administered by the oral route. Either systemic or oral immunization with U-Omp16 elicits a Th1 specific response. These abilities of U-Omp16 indicate that it is endowed of self-adjuvanting properties. The adjuvanticity of U-Omp16 could be explained at least in part by its capacity to activate dendritic cells in vivo. U-Omp16 is able also to stimulate dendritic cells and macrophages in vitro. The latter property and its ability to induce a protective Th1 immune response against B. abortus infection have been found to be TLR4-dependent. The fact that U-Omp16 is an oral protective Ag and it possesses a mucosal self-adjuvanting property, led us to develop a plant made vaccine expressing U-Omp16. Our results indicate that plant-expressed recombinant U-Omp16 is able to confer protective immunity when is given orally, indicating that a plant-based oral vaccine expressing U-Omp16 could be a valuable approach to control this disease.