IMMUNOLOGICAL CROSS-REACTIVITY BETWEEN A CLONED ANTIGEN OF ONCHOCERCA-VOLVULUS AND A COMPONENT OF THE RETINAL-PIGMENT EPITHELIUM

Onchocerciasis (river blindness) is a major blinding disease in Africa, Central America, and South America. Loss of vision can be due to corneal change, optic atrophy, or chorioretinal disease. It has been suggested that autoimmunological reactions resulting from crossreactivity between parasite antigens and components of eye tissues contribute to development of ocular pathology. Using sera collected from onchocerciasis patients as a screening reagent, a cDNA clone (Ov39) has been isolated from a lambda-gt11 expression library of Onchocerca volvulus. This antigen exhibits immunological crossreactivity with a component of retinal pigment epithelium cells (RPE). Antiserum raised against this recombinant peptide immunoprecipitates a 22,000 M(r) antigen of adult O. volvulus and recognizes a 44,000 M(r) component of bovine RPE by Western blotting. A 44,000 M(r) antigen of cultured human RPE metabolically labeled with S-35-methionine can be immunoprecipitated with the same antiserum. An antigen of the same size is recognized by a rabbit antiserum raised against whole O. volvulus extract. Immunocytochemical studies on cryostat sections of the bovine eye using the antirecombinant sera localizes this antigen to the RPE.