A sinthetic peptide derived from Omp31 elicits a Th1 response and confers similar levels of protection against Brucella melitensis than whole Omp31?

PASQUEVICH, K.A; ESTEIN S.; DE LA BARRERA, S.; BOWDEN, R.; FOSSATI, C.; GIAMBARTOLOMEI, G.H.; CASSATARO, J.

Córdoba

Congreso; VII Latin American Congress of Immunology (ALAI); 2005

A SYNTHETIC PEPTIDE DERIVED FROM OMP31 ELICITS A TH1 RESPONSE AND CONFERS SIMILAR LEVELS OF PROTECTION AGAINST BRUCELLA MELITENSIS THAN WHOLE OMP31. K.A.Pasquevich1,2, S. Estein3, S.de la Barrera4, R. Bowden3, C.Fossati2, G.H.Giambartolomei1,2, J.Cassataro1,2 Lab. de Inmunogenética, Hospital de Clínicas, UBA1; IDEHU-CONICET (UBA)2. Lab. de Inmunología, UNICEN, Tandil3. IIHEMA4. Argentina. Previous results demonstrate that the recombinant outer membrane protein of 31kDa from Brucella melitensis (rOmp31) induce a specific T helper (Th) 1 response and confers protection against B. melitensis. In the present work in vitro T cell subset depletion showed that rOmp31 immunization elicited specific CD4+ Th1 cells while CD8+ T cells induced cytotoxic activity. In vivo depletion of T cell subsets showed that the rOmp31 elicited protection against B. melitensis infection is mediated by CD4+ T cells and CD8+ T cells did not contribute. We then studied a known exposed region from Omp31 on the Brucella membrane that comprises aminoacids (aa) 48-74 of Omp31. We evaluated the immunogenicity and protective efficacy of the 27aa synthetic peptide (Omp3148-74) in incomplete Freund´s adjuvant. Immunization with the peptide did not elicit specific humoral responses but elicited a Th1 response mediated by CD4+ T cells. Omp3148-74 conferred significant (p0.05) to those obtained with rOmp31 (1.24 log). The attenuated control vaccine Rev-1 induced 2.33 log protection. Finally, the finding that Omp3148-74 is a Th1 protective peptide will contribute in the development of a multivalent subunit vaccine against Brucella spp carrying only protective epitopes.