The antigenic sources of adult and the third larval (L3) stages of Brugia pahangi were detected by indirect immunofluorescent technique. Six panels of antisera were used, including human antisera against Brugia malayi and Wuchereria bancrofti, cat antisera against B.malayi and B.pahangi and jird antisera against B.malayi and B.pahangi as primary antibodies. All antisera gave the same results, although four of the six were not infected by B.pahangi. This indicates non-species specificity, and B.pahangi, B.malayi and W.bancrofti must share most of the common antigenic molecules. All antisera reacted well with the surface of L3 B.pahangi in the whole mount preparation. This indicates non-stage specificity. The most intense fluorescence was located at the epicuticle, the basal lamina lining the body wall, the gut and the reproductive tract, the egg shell in utero and the sperm. The hypodermis, the muscle cells, the cuticle beneath the epicuticle, the epithelial cells of the gut and the reproductive tract showed moderate fluorescence. The least fluorescence was observed in the egg interior.
