Expression of C-terminal truncated and full-length Babesia bigemina rhoptry-associated protein 1 and their potential use in enzyme-linked immunosorbent assay.

Recombinant antigen-based enzyme-linked immunosorbent assay (ELISA) was developed for the serological diagnosis of Babesia bigemina infection by using a full-length B. bigemina rhoptry-associated protein 1 (rRAP-1) and the truncated C-terminal RAP-1 (rRAP-1/CT). While the rRAP-1 showed cross reactivity between B. bigemina- and Babesia bovis-infected bovine sera, the rRAP-1/CT was highly specific to B. bigemina-infected bovine sera and proved useful in the detection of sequential sera collected from an experimentally infected cow during the acute and latent infection. The high yield of soluble rRAP-1/CT and its diagnostic specificity demonstrate its potential in the diagnosis of B. bigemina infection. Its usefulness for epidemiological investigation is currently being evaluated.