ANALYSIS AND LOCALIZATION OF CYCLOPHILIN-A FOUND IN THE VIRIONS OF HUMAN-IMMUNODEFICIENCY-VIRUS TYPE-1 MN STRAIN

Previous reports have shown that cyclophilin A (CyPA) is found to be specifically associated with human immunodeficiency virus type-1 (HIV-1) virions and is required for infectivity (Franke et al. Nature 372:359; Thali et al, Nature 372:363). We have examined CyPA associated with HIV-1(MN) virions, Virions from infected human lymphoid cells were analyzed by high-pressure liquid chromatography (HPLC), protein sequence, and immunoblot analysis. At least three forms of CyPA were found: an unmodified form, an N-terminally modified form, and an N-terminally modified form that migrates as a larger isoform on a reducing-SDS polyacrylamide gel, Using a protease digestion procedure, CyPA that is associated with virions was found to be located inside the viral membrane, Similar examination of SIVMne produced by HUT-78 human T cells did not detect specific incorporation of CyPA into SIV virions, Our results are consistent with the role of CyPA acting early in the infectious process of HIV-1.