The role of two retroviruses, walleye epidermal hyperplasia virus types 1 and 2 (WEHV1 and WEHV2), in the etiology of discrete epidermal hyperplasia in walleyes will be examined. These hyperplastic lesions resemble psoriatic plaques in humans and skin lesions that appear on HIV Tat transgenic mice. WEHV1 and 2 resemble complex retroviruses and it is hypothesized that the expression of accessory genes is involved in cellular proliferation. To study the induction and regression of walleye epidermal hyperplasia transcription maps will be developed to examine splicing patterns, exon usage, and cDNA complexity. Antibodies to viral structural and accessory proteins will be produced to study the WEHV replicative cycle in cultured cells. Hyperplasia induction and regression will be followed with nucleic acid probes and antibodies to identify viral gene products implicated in these processes.