AN ENZYME-LINKED-IMMUNOSORBENT-ASSAY (ELISA) FOR THE DETECTION OF ANTIBODIES AGAINST BABESIA-BOVIS IN CATTLE

A method for the isolation of Babesia bovis merozoites from infected e rythrocytes (Machado et al., 1994) and an enzyme-linked immunosorbent assay (ELISA) for the detection of anti-B. bovis antibodies were devel oped. This ELISA utilizes a soluble, alkali-digested B. bovis antigen. Sera from calves experimentally infected with B. bovis were screened by this technique from day 9 to day 233 postinfection (PI). Maximum ti ters were reached between days 29 and 149 PI. Sera from calves (n = 62 ), heifers (n = 38) and cows (n = 49), raised in tick-infested areas o f Sao Paulo State, showed higher antibody levels in heifers and cows. A higher percentage of negative sera (19.4%) was found among calves, S odium dodecyl sulphate-polyacrylamide electrophoresis (SDS-PAGE) and i mmunoblotting have identified proteins of similar molecular mass in th e two species. Sera from calves experimentally infected with B. bovis reacted with homologous antigens at the level of 95, 66 and 23 kDa. Th e same serum reacted with the 23 kDa band of heterologous antigen. Ser a from calves experimentally infected with B. bigemina recognized 82, 66, 58, 36 and the 23 kDa polypeptides of homologous and heterologous antigens. The experimental ELISA described may prove to be a practical serological test for bovine Babesia infection with the choice of spec ific test antigen for B. bovis and B. bigemina. (C) 1997 Elsevier Scie nce B.V.