ABSTRACT
This study was designed to prepare monoclonal antibodies [MAbs] against filarial worm antigen [FWA] with immunodiagnostic potential for human filariasis. These MAbs were initially screened and then tested for their specificities against different parasite antigens [S.mansoni SEA, Echinococus granulosus and Fasciola hepatica] by ELISA. From a panel of anti-filarial antigen MAbs; a pair of MAbs [9F/10B and 5F1 611], highly reactive with filarial antigen and showing no cross reactivity against other parasites antigens were selected and characterized. The pair was found to be of IgG1 subclass. Identification of target antigens recognized by MAbs was performed using immunoelectrophoresis, SDS-polyacrylamid gel electrophoresis and enzyme-linked immunoelectrotransfer blot techniques. Both MAbs recognized one band with 88 kDa molecular weight by western blots. Chemical nature of MAbs target antigens was identified by periodate treatment method and proved to be glycoprotein in nature. The pair of MAbs was employed in sandwich ELISA for the defection of circulating filarial antigen [CFA]; one MAb [9F/10B] was used as antigen capturing antibody and the other [5F/6H] as peroxidase-conjugated antigen detecting antibody. The assay reached a lower detection limit of 125 ng/ml of filarial antigen. CFA levels were measured in serum samples from 71 filariasis patients [47 with microfilaraemia and 24 with elephantiasis], 45 patients with other parasites including schistosomiasis, fascioliasis and echinococcosis and 39 healthy individuals as negative control. CFA levels were detected in sera of 68 out of 71 filariasis patients showing an overall sensitivity of 95.8% [91.7% sensitivity for microfilaraemia group and 100% sensitivity for elephantiasis group]. All negative control sera were negative for CFA, while 3 patients out of the other parasite group were positive for CFA giving an overall specificity of 96.4%. These findings suggest that [9F/IOB] MAb and [5F/6H] MAb could be used as a reliable diagnostic indicator for the activity of human filariasis and as a cure monitor particularly in control programs for endemic areas