Anti-leishmanial polyclonal antibodies to assess the performance characteristics of leishmanial antigen detection ELISA.

The polyclonal antibodies raised in rabbits against amastigote antigen extract were purified and fractionated, and IgG class antibodies and from the same antibodies, a peroxidase conjugate (labeled antibodies) reagent were prepared. The antibodies and the labeled antibodies were analyzed for efficacy of the homologous extracted antigens by capture ELISA. The titration curves of the anti-amastigote IgG antibody against extracted antigens showed that both free antibody and corresponding labeled antibody reacted with the original amastigote antigens. Further analysis involved the interaction between the antibody and two leishmanial stages; mammalian amastigote & infective promasitgote by immunoflourescene technique. The strong interaction was not only with surface antigenic components of the stages but also with their internal components. Capture-ELISA system was done to detect specific leishmanial antigens in urine and sera from visceral leishmaniasis patients (VL). Most of the urine samples were positive (90% sensitivity) for leishmanial antigens without cross-reactivity (100% specificity) with any other tested samples from heterologous parasitic infections. But, only 61% sensitivity and 53% specificity were obtained when the capture ELISA was done to detect the specific leishmanail antigens in sera from VL.