Identification of the surface polypeptide antigens of the infective larvae of Onchocerca volvulus

The surface polypeptide antigens of third-stage infective larvae (L 3) and adult males of Onchocerca volvulus have been compared after iodogen-catalysed radioiodination, separation by sodium dodecyl sulphate-polyacrylamide gel electrophoresis in β-mercaptoethanol followed by autoradiography. L 3 surfaces contained polypeptides with apparent molecular weights of 14, 18·5, 26, 34, 51, 68 and 130 kDa, whereas the adults contained 14, 19, 26, 34, 37·5 and 68 kDa components. By immunoprecipitation with patient's sera, only the 14 and 18·5 kDa components were shown to be antigenic on the L 3, the other components being unreactiye with patients' antibodies. Under similar conditions, 4 of the 6 adult male polypeptides reacted with patients' antisera, confirming their antigenic nature. Lentil lectin and immunosorbent chromatography of the surface components revealed the 18·5 kDa and 68 kDa antigens of L 3 and adult males respectively to be glycoproteins. The apparently weak reactivity of L 3 surface components with host antibody may be part of an escape mechanism that favours the establishment of O. volvulus in human hosts.