USE OF FRACTIONATED URINARY FILARIAL ANTIGEN IN THE DIAGNOSIS OF HUMAN FILARIASIS

Fractionated urinary filarial antigen UFA C2 has shown high antigenic activity after absorption of urinary albumin present in the fraction. As little as 500 ag (10(-18) g) of albumin absorbed UFA C2, labelled a s UFA C2-A, was found to be sufficient to detect filarial antibody. St ick enzyme immunoassay to assess the immunodiagnostic potential of UFA C2-A indicated filarial IgG antibody in 89% of microfilaraemic (mf) c ases, 84% of clinical filariasis and 7% of endemic normals. UFA C2-A w as found to be present in circulation in active as well as clinical in fections as observed by inhibition assay using UFA C2-A penicillinase conjugate. Eighty-six per cent of mf, 50% of clinical cases and 6% of endemic normal subjects revealed parasite antigen to UFA C2-A on furth er serological analysis. None of the non-endemic normal sera showed th e presence of filarial antibody/antigen to UFA C2-A. Furthermore, the test to determine phosphorylcholine (PC) bearing epitopes in UFA C2-A indicated no immunological reaction with anti-PC monoclonal antibody b y avidin-biotin enzyme linked immunosorbent assay (ELISA). The highly sensitive and more easily obtainable non-PC urinary filarial antigen, UFA C2-A, is of great immunodiagnostic interest for lymphatic filarias is.