Submitted to: Journal of Clinical Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/8/2003
Publication Date: 4/1/2004
Citation: Boonchit, S., Xuan, X., Yokoyama, N., Goff, W.L., Waghela, S.D., Wagner, G., Igarashi, I. 2004. Improved Enzyme-Linked Immunosorbent Assay Using C-Terminal Truncated Recombinant Antigens of Babesia bovis Rhoptry-Associated Protein-1 for Detection of Specific Antibodies. Journal of Clinical Microbiology. 42(4):1601-1604. Interpretive Summary: Babesia bovis is a tick-transmitted microorganism, causing disease in cattle throughout much of the tropical and subtropical world. Other related species of Babesia also cause disease, but each in a slightly different way. In addition, more than one species occurs many areas. Thus, assays for differentiating between different babesial species are very important. However, these specific assays are not available in formats that allow for easy and quick diagnosis. In this study, we confirm our previous work that described a protein associated with Babesia bovis that was used to detect antibody present in infected cattle, and further define the portion of the protein that accounts for cross-reactivity and the portion that is recognized specifically (no cross-reactivity).
Technical Abstract: An enzyme-linked immunosorbent assay (ELISA) based on a recombinant rhoptry-associated protein-1 (RAP-1) of Babesia bovis has been previously developed, but it was imperfect because some cross-reactions were still present in B. bigemina-infected bovine sera. To improve its accuracy for the specific detection of antibodies to B. bovis, we constructed three C-terminal truncated recombinant antigens of the RAP-1, rCT1 (amino acid residues (aa) 301 to 408), rCT2 (aa 388 to 490), and rCT3 (aa 466 to 565), by using a baculovirus expression system, and evaluated their diagnostic potential using ELISA. The rCT1 and rCT2 were better diagnostic antigens in their sensitivities and diagnostic efficiencies that rCT3, although none of the recombinant antigens showed any cross-reactivity to B. bigemina-infected bovine sera. These results confirm that the N-terminal 300-amino acid region caused cross-reactivity of the entire RAP-1 antigen, and the C-terminal truncated antigens were shown to be useful reagents for species-specific serodiagnosis.