Detection of circulating antigen in bancroftian filariasis by using a monoclonal antibody

A monoclonal antibody designated Gib 13-5-2 (Gib 13) and directed against the cattle parasite Onchocerca gibsoni was used in a two-site immunoradiometric assay (IRMA) for detection of circulating antigen in the sera of Wuchereria bancrofti-infected individuals from Sri Lanka and Papua New Guinea. The microfilaremic patients were, in general, serum antigen positive by the Gib 13 IRMA. Among the amicrofilaremic patients, 47% of those with lymphedema, lymphangitis, hydrocele, etc., and 25% of those with elephantiasis had circulating antigen. Correlation of the presence of serum antigen with clinical status indicated that the Gib 13 target antigen in serum is probably an indicator of either active or early infection, or of both. The antigen was also detected in the urine of some patients. By sodium dodecyl sulphate polyacrylamide gel electrophoresis immunoblotting, Gib 13 target antigens of molecular weights 67,000 and 52,000 were identified.