title: Nef association with human immunodeficiency virus type 1 virions and cleavage by the viral protease.
abstract: Nef is a regulatory gene product of human immunodeficiency virus type 1 (HIV-1) and other primate lentiviruses which enhances virion infectivity by an unknown mechanism. We report here that Nef is detectable at moderate levels in preparations of HIV-1 virions which lack active viral protease (PR). Significantly smaller amounts of intact Nef were present in wild-type virion preparations. Instead, a smaller Nef-related product with an apparent molecular mass of 18 kDa was associated with wild-type virions, indicating that packaging of Nef resulted in cleavage by the viral PR. The presence of the HIV-1 PR inhibitor A77003 during virus production prevented the appearance of the 18-kDa Nef product and caused an accumulation of full-length Nef in virion preparations. Nef associated with comparable efficiency with viral particles produced by the Gag polyproteins of HIV-1 and Moloney murine leukemia virus, indicating that no specific interaction with a virion component is required for the incorporation of Nef. The N-terminal 86 amino acids of Nef were sufficient for packaging into virions. A nonmyristylated form of Nef associated with viral particles with considerably lower efficiency, suggesting that Nef gains access into nascent virions primarily as a consequence of its affinity for membranes. Our results raise the possibility that Nef enhances infectivity directly as a component of the virion.
authors.affiliation: Division of Human Retrovirology, Dana-Farber Cancer Institute, and Department of Pathology, Harvard Medical School, Boston, Massachusetts 02115, USA.
authors.forename: A A
authors.initials: AA
authors.lastname: Bukovsky
authors.forename: T
authors.initials: T
authors.lastname: Dorfman
authors.forename: A
authors.initials: A
authors.lastname: Weimann
authors.forename: H G
authors.initials: HG
authors.lastname: Göttlinger
mesh_terms: D010450:Endopeptidases / Q000235:genetics*; D015967:Gene Expression Regulation, Viral; D015754:Genes, nef; D015497:HIV-1 / Q000235:genetics*; D006801:Humans; D014771:Virion / Q000235:genetics*
chemical_list: D010450:Endopeptidases