The primary goal of this project has been to develop an enumeration assay for infectious HIV. In an initial phase we generated a series of monoclonal antibodies in mice which recognize the HIV envelope protein. The preliminary results indicate that the antibodies will detect HIV antigens on live, infected cells as well as methanol-fixed, infected cells by indirect immunofluorescence. Current studies are in progress to determine which of the two envelope glycoprotein components are recognized by these monoclonal antibodies. Subsequently the antibodies will be used to examine whether HIV infected cells present in blood of AIDS patients can be detected using FACS analysis. We are also continuing our efforts to develop a sensitive cell line which can be used in assays for infectious HIV. Approaches include fusion of sensitive suspension cell lines to cell lines capable of attaching to plastic surfaces as well as transfer of CD- 4 genes into various attached cell lines. These cell lines are now being screened for their ability to be infected in vitro by HIV.