title: Downregulation of cell-surface CD4 expression by simian immunodeficiency virus Nef prevents viral super infection.
abstract: The nef gene product encoded by the mac239 proviral clone of simian immunodeficiency virus (SIV) markedly enhances viral replication and pathogenesis in vivo. We have used this biologically active nef isolate to examine the phenotype of Nef in retrovirally transduced human T cells in culture. SIV Nef is shown to dramatically inhibit cell-surface expression of the CD4 glycoprotein without significantly affecting the total steady-state level of cellular CD4. This downregulation of the cell-surface CD4 receptor for human immunodeficiency virus type 1 (HIV-1) infection correlated with the acquisition of resistance to superinfection by HIV-1. However, SIV Nef did not affect the level of gene expression directed by the HIV-1 long terminal repeat. It is hypothesized that downregulation of cell-surface CD4 by Nef facilitates the efficient release of infectious progeny virions and, hence, viral spread in vivo.
authors.affiliation: Howard Hughes Medical Institute, Duke University Medical Center, Durham, North Carolina 27710.
authors.forename: R E
authors.initials: RE
authors.lastname: Benson
authors.forename: A
authors.initials: A
authors.lastname: Sanfridson
authors.forename: J S
authors.initials: JS
authors.lastname: Ottinger
authors.forename: C
authors.initials: C
authors.lastname: Doyle
authors.forename: B R
authors.initials: BR
authors.lastname: Cullen
mesh_terms: D015704:CD4 Antigens / Q000032:analysis*; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology / Q000382:microbiology*; D002460:Cell Line; D015536:Down-Regulation; D015693:Gene Products, nef / Q000032:analysis / Q000502:physiology*; D015754:Genes, nef; D016325:HIV Long Terminal Repeat; D015497:HIV-1 / Q000235:genetics / Q000502:physiology*; D006801:Humans; D015302:Simian Immunodeficiency Virus / Q000235:genetics / Q000502:physiology*; D015163:Superinfection; D054311:nef Gene Products, Human Immunodeficiency Virus
chemical_list: D015704:CD4 Antigens; D015693:Gene Products, nef; D054311:nef Gene Products, Human Immunodeficiency Virus