Mycobacterium bovis BCG expressing Msp1a of Anaplasma marginale: avaccine candidate against bovine anaplasmosis.

by Michelon, André

The vaccinal strain Mycobacterium bovis BCG was used to express Msp1aprotein of Anaplasma marginale. The msp1a gene was amplified by PCR from A. marginale DNA extracted from bovine erythrocytes, cloned into pUS2000 andpMIP12 vectors, and then used to transform BCG. Mice were immunized withrecombinant BCG on days 0 and 21 of the experiment. The groups wereinoculated with saline solution (T1), BCG (T2), BCG/pUS2000/msp1a (T3) andBCG/pMIP12/msp1a (T4). Forty-two days post-inoculation (dpi), mice of treatment3 and 4 developed humoral immune response against the Msp1a antigen. TheELISA showed an antibody response peak at 63 dpi. Mice of group 4 showed ahigher immune response than other groups tested (P<0,001). Specific interferongammaproduction against Msp1a was detected in splenocytes of mice immunizedwith rBCG at 49 dpi, and the group 4 showed the highest level of this cytokine inELISA. Antibodies of groups 3 and 4 were able to recognize native Msp1a fromerythrocyte extract from A. marginale. The monoclonal antibody ANA22B1,specific to a Msp1a epitope, was able to recognize rMsp1a, produced byEscherichia coli and BCG. The results obtained in this study places rBCGexpressing Msp1a of A. marginale as a potential vaccine candidate against bovineanaplasmosis.