EXPRESSION OF THE HUMAN-IMMUNODEFICIENCY-VIRUS TYPE-1 (HIV-1) NEF GENE DURING HIV-1 PRODUCTION INCREASES PROGENY PARTICLE INFECTIVITY INDEPENDENTLY OF GP160 OR VIRAL ENTRY

The nef gene product of human immunodeficiency virus type 1 (HIV-1) pr omotes more-rapid kinetics of viral replication in primary peripheral blood mononuclear cells. We have previously shown that these enhancing effects of Nef on HIV-1 replication reflect an increase in viral infe ctivity detectable both in limiting dilution assays and through a sing le-cycle infection of the HeLa-CD4-long terminal repeat-beta-galactosi dase indicator cell line. We now demonstrate that nef-defective HIV-1 can be rescued to near wild-type levels of infectivity by coexpressing Nef in trans in the cell line producing the virus. This observation i ndicates that HIV-1 virions produced in the presence of Nef are intrin sically different. However, we show that the major viral structural pr oteins are quantitatively similar in purified viral preparations. We a lso demonstrate the functional equivalence of the gp120-gp41 envelope glycoprotein complexes of Nef(+) and Nef HIV-1 through an assay for vi ral entry. Finally, we show that env-defective Nef(+) HIV-1 pseudotype d with an amphotropic envelope is also more infectious than similarly pseudotyped Nef HIV-1. Thus, the production of HIV-1 in the presence o f Nef results in viral particles that are more infectious, and this in creased infectivity is manifested at a stage after viral entry but pri or to or coincident with HIV-1 gene expression.