A Recombinant S19 Brucella abortus expressing a Babesia bovis antigen is immunostimulatory

SABIO Y GARCÍA J,; MACEDO, G; BARSANTE, M; CARVALHO, N; CARRICA, M; FARBER, M; CRAVERO, S; CAMPOS, E; COSTA, S; ROSSETTI, O

Pinamar, Buenos Aires

Congreso; PABMB 10th Congress-Panamerican Association for Biochemistry and41st Annual Meeting Argentine Society for Biochemistry and Molecular Biology; 2005

Sociedad Argentina de Investigación Bioquímica y Biología Molecular

Due to the strong cellular and humoral immune response that S19Brucella abortus (live vaccine) elicits, it is an attractive vector forthe delivery of heterologous antigens. The objective of the presentstudy is to express antigens of pathogens that require the same type of immune response elicited by Brucella to control the deseasethey produce. S19 B. abortus expressing RAP1a (a conservedimmunogenic antigen) of Babesia bovis were generated. rap1a wasPCR-amplified as a complete version or without the sequence that encodes for its signal peptide. The amplicons were subcloned underdifferent promoters and signal se-quences: lacz, bp26 and omp19 tostudy diverse subcelular localizations. BP26 is a peri-plasmic proteinand OMP19 is associated to the outer membrane of Brucella spp. RAP1a as a fusion with the first aminoacids of either ß-galactosidaseor OMP19 resulted in the expresion of RAP1 in association to themembrane of S19. Even though there was a relatively lower stabilityof the plasmids containing rap1a, compared to the empty plasmid, mice inoculated with S19pRAP or S19p19RAP developed specificimmune responses to RAP1, being IgG2a the prominant subisotypeof antibodies (analysed by ELISA). As a fusion protein with BP26,RAP1a was toxic. Therefore it can be concluded that the expression of RAP1 in B. abortus S19 is possible and immunostimulatory.Lymphocyte stimulation assays are being performed.