Specific antibody to a conserved region of Babesia apical membrane antigen-1 inhibited the invasion of B. bovis into the erythrocyte.

Apical membrane antigen-1 (AMA-1) is a microneme protein that exists in all apicomplexan parasites and plays an indispensable role in the invasion into host cell. Central region of ectodomains I and II of Babesia bovis apical membrane antigen-1 (BbAMA-1P) is highly conserved with these of Babesia species and may be beneficial for vaccine development against babesiosis. In the present study, recombinant protein encoding the central region of B. bovis AMA-1 (rBbAMA-1P) was produced in Escherichia coli and its antiserum was prepared in mice for further molecular characterization. Anti-rBbAMA-1P serum specifically reacted with corresponding authentic protein of B. bovis as determined by Western blotting and IFAT. Cultured B. bovis treated with anti-rBbAMA-1P serum showed significant reduction in the in vitro growth of the parasites. Moreover, preincubated free merozoites with 1mg/ml anti-rBbAMA-1P serum inhibited their efficiency in the invasion into erythrocytes (RBCs) by 61% and 70% at 3h and 6h, respectively. Our data suggest that the central region of domains I and II of BbAMA-1 may serve as a vaccine candidate against babesiosis.