A 29-kDa merozoite protein is a prospective antigen for serological diagnosis of Babesia orientalis infection in buffaloes

A gene encoding a 29-kDa protein of Babesia orientalis (BoP29) was isolated by immunoscreening the B. orientalis cDNA expression library using monoclonal antibodies and its nucleotide sequence of the cDNA was 971 bp with an open reading frame of 750 bp. The results of BLASTn and BLASTx in NCBI showed that this cDNA sequence had similarity with Babesia bovis hypothetical protein (BBOV_II005480). Western blotting showed that the recombinant protein (rBoP29) had positive seroreactivity to B. orientalis infected buffalo sera. An indirect enzyme-linked immunosorbent assay (ELISA) was developed using the rBoP29 as antigen. This method could detect specific antibody variation in the sera from the buffaloes experimentally infected with B. orientalis. Analysis of 132 sera samples collected from buffaloes showed that there was no significant difference in relative effectiveness of rBoP29-ELISA and PCR (χ2 = 0.910; P = 0.897) in identifying positive samples. These results indicate that the BoP29 is a novel antigen of B. orientalis, and rBoP29 might be a good antigen candidate for diagnosis of B. orientalis infection in buffalo.