DIAGNOSIS OF CATTLE FASCIOLIASIS BY THE DETECTION OF A CIRCULATING ANTIGEN USING A MONOCLONAL-ANTIBODY

A monoclonal antibody (MoAb) 1C12 that reacts with a 66 kDa surface te gumental (ST) antigen of adult worms of Fasciola gigantica was used to detect circulating antigen in sera of experimentally and naturally in fected cattle. A combination of rabbit anti ST-antigens and MoAb 1C12 were used to capture and detect the circulating antigen in sandwich EL ISA, The dilutions of 1:1,000 of rabbit anti ST-antigens and 1:100 for MoAb 1C12 were used to reduce cross-reactivity with other trematodes' antigens. The circulating antigen of F. gigantica was demonstrated in sera of all experimentally infected animals as early as the first wee k after the infection, and it remained detectable until the experiment was terminated at week 32 after the infection. Of the 97 serum sample s from naturally infected cattle, the sensitivity of 86.6% was observe d when the cut-off point was calculated from 32 serum specimens from u ninfected control calves. The sensitivity increased to 100% when the c ommercial fetal calf and trematode-free baby calves sera were used for calculation of the control cut-off point. Based on these results, the combination of rabbit anti ST-antigens and MoAb 1C12 sandwich ELISA a ppeared to be sensitive, specific, and applicable in the immunodiagnos is of fasciolosis in cattle for epidemiological study and monitoring o f chemotherapeutic efficacy.