Partial characterization of 2-beta-mercaptoethanol-soluble surface-associated antigens of Onchocerca volvulus

Antigens were extracted from the epicuticle/cuticle of intact female Onchocerca volvulus using 2% 2-beta-mercaptoethanol and 1% SDS. In Western blot analysis a human infection serum selected for its high antibody titre against whole worm homogenates did not recognize any component solubilized by 1% SDS. However, the same serum did bind at least 7 antigens among the material extracted with 2-beta-mercaptoethanol. These antigens have apparent molecular weights (Mr) of: 15,000, 18,000, 28,000, 78,000, 98,000, 120,000 and 200,000. In ELISA using this preparation as target antigen, 151 out of 153 human infection sera gave positive results. An Onchocerca-specific IgG1 monoclonal antibody, designated Cam1, recognized the 28,000 Mr antigen, which is the most prominent antigen detected by Western blot analysis using human infection sera. In ELISA, using material affinity-purified with Cam1 as target antigen, 149 out of 153 human infection sera gave a positive IgG response. From a cDNA library three expressing clones were isolated with a rabbit serum raised against 2-beta-mercaptoethanol solubilized material. One of these clones was recognized by the monoclonal antibody Cam1.