A NEW REPORTER SYSTEM FOR DETECTION OF RETROVIRAL INFECTION

We describe a novel reporter molecule, the murine surface antigen Thy- 1, useful for immunoselection and detection of retrovirus-mediated tra nsduction by flow cytometry. A cDNA encoding the murine thy-1 gene was isolated and cell surface expression of its gene product was demonstr ated. The Thy-1 glycoprotein was tested as a cell surface reporter mol ecule in the context of replication-defective and competent retrovirus es. Cells transduced via murine retroviral vectors carrying the thy-1 and the neomycin phosphotransferase genes express Thy-1 glycoprotein o n surfaces. The Thy-1 marker is potentially useful in gene transfer pr otocols because selection of transduced cells can be achieved by immun oselection with anti-Thy-1 antibodies shortly after infection with the retroviral vector. In addition, a human immunodeficiency virus type 1 (HIV-1) recombinant expressing Thy-1 is described, which is replicati on-competent and syncytium-inducing in human peripheral blood mononucl ear cells (PBMCs) and immortalized CD4-positive cell lines. Cells infe cted with this HIV-1 recombinant express Thy-1 on their surfaces and c an be detected and purified by fluorescence-activated cell sorting (FA CS). Because of these properties, retroviruses expressing this genetic marker can be useful for studies in gene therapy and of the retrovira l life-cycle.