Preliminary identification and characterization of antigen extracts from Onchocerca volvulus

Sequential extraction of Onchocerca volvulus from skin nodules with buffers of different ionic strength resulted in a mixture of antigens which reacted in double immunodiffusion with sera from proven cases of onchocerciasis, the number of precipitation lines varied from 1 to 5. Triton X-100 detached mainly cationic antigen proteins. It reduced the molecular size of many antigenic proteins, but did not effect their antigenicity. Labelling of the extracted proteins with high specific activity 125I did not destroy much antigenicity. Strong cross-reactivity between Onchocera volvulus extracts and Onchocerca gutturosa and Litomosoides carinii was observed, less with extracts of Necator americanus and Ascaris suum, and none with Echinococcus multilocularis. Sera from proven cases of wuchereriasis, toxoplasmosis and echinococcosis rarely contained antibodies against O. volvulus. Isoelectric focusing, immunoelectrophoresis and gel filtration of the O. volvulus extracts indicated a variety of antigens. Preliminary attempts were made to purify the antigens using a solid-phase immuno-adsorbent prepared by coupling purified onchocerciasis IgG to CNBr-activated Sepharose.