title: Selective CXCR4 antagonism by Tat: implications for in vivo expansion of coreceptor use by HIV-1.
abstract: Chemokines and chemokine receptors play important roles in HIV-1 infection and tropism. CCR5 is the major macrophage-tropic coreceptor for HIV-1 whereas CXC chemokine receptor 4 (CXCR4) serves the counterpart function for T cell-tropic viruses. An outstanding biological mystery is why only R5-HIV-1 is initially detected in new seroconvertors who are exposed to R5 and X4 viruses. Indeed, X4 virus emerges in a minority of patients and only in the late stage of disease, suggesting that early negative selection against HIV-1-CXCR4 interaction may exist. Here, we report that the HIV-1 Tat protein, which is secreted from virus-infected cells, is a CXCR4-specific antagonist. Soluble Tat selectively inhibited the entry and replication of X4, but not R5, virus in peripheral blood mononuclear cells (PBMCs). We propose that one functional consequence of secreted Tat is to select against X4 viruses, thereby influencing the early in vivo course of HIV-1 disease.
authors.affiliation: Laboratories of Molecular Microbiology and Host Defenses, National Institute of Allergy and Infectious Diseases, Bethesda, MD 20892-0460, USA.
authors.forename: H
authors.initials: H
authors.lastname: Xiao
authors.forename: C
authors.initials: C
authors.lastname: Neuveut
authors.forename: H L
authors.initials: HL
authors.lastname: Tiffany
authors.forename: M
authors.initials: M
authors.lastname: Benkirane
authors.forename: E A
authors.initials: EA
authors.lastname: Rich
authors.forename: P M
authors.initials: PM
authors.lastname: Murphy
authors.forename: K T
authors.initials: KT
authors.lastname: Jeang
mesh_terms: D000998:Antiviral Agents / Q000378:metabolism / Q000502:physiology*; D001483:Base Sequence; D002460:Cell Line; D015686:Gene Products, env; D015696:Gene Products, tat / Q000378:metabolism / Q000502:physiology*; D006679:HIV Seropositivity / Q000378:metabolism; D015497:HIV-1 / Q000502:physiology*; D006801:Humans; D008561:Membrane Fusion / Q000502:physiology; D011485:Protein Binding; D019718:Receptors, CXCR4 / Q000037:antagonists & inhibitors* / Q000737:chemistry / Q000378:metabolism; D054322:tat Gene Products, Human Immunodeficiency Virus
chemical_list: D000998:Antiviral Agents; D015686:Gene Products, env; D015696:Gene Products, tat; D019718:Receptors, CXCR4; D054322:tat Gene Products, Human Immunodeficiency Virus