Transform culture human diploid vascular endothelial cells with non-viable, endonuclease-cleaved late gene regions of human papovavirus DNA. Examine transforming activity of UV-inactivated viruses Perform comparative analyses of antigenic relationships between the T-antigens induced by BK, JC, and SV40 viruses. Analyze malignant properties of papovavirus-transformed cells in athymic nude mice and semi-solid media. Establish cloned lines of virus-transformed human cells and characterize the structures of the integrated viral DNA. Study rescue of virus from transformed lines by cell fusion techniques. Perform immunological analysis of viral antigen expression and determine the amount of DNA replication in acute virus infections. Determine the fate of differentiated endothelial markers (clotting factor VIII antigen, angiotensionconverting enzyme, Weibel-Palade bodies) in virally transformed cells.