title: An 85-aa segment of the GB virus type C NS5A phosphoprotein inhibits HIV-1 replication in CD4+ Jurkat T cells.
abstract: GB virus type C (GBV-C) is an apparently nonpathogenic virus that replicates in T and B lymphocytes and is a common cause of persistent human infection. Among HIV-1-infected individuals, persistent coinfection with GBV-C is associated with prolonged survival, and infection of blood mononuclear cells or CD4+ T cells with GBV-C and HIV in vitro results in significantly reduced HIV-1 replication. To date, the viral protein(s) that lead to HIV inhibition have not been identified. The GBV-C nonstructural phosphoprotein (NS5A) is predicted to have pleotropic effects on cells, including interactions with the IFN-induced dsRNA-activated protein kinase (PKR). We studied GBV-C NS5A to determine whether it is involved in inhibition of HIV replication. GBV-C NS5A protein from an isolate that was cleared by IFN therapy did not inhibit PKR, whereas NS5A from an isolate that was not cleared by IFN-inhibited PKR function in a yeast genetic system. Both of these GBV-C NS5A proteins were expressed in a CD4+ T cell line (Jurkat), and both induced a potent, dose-dependent inhibition of HIV-1 replication, thus the effect was independent of PKR inhibition. NS5A induced the release of the chemokine SDF-1 and decreased surface expression of the HIV coreceptor CXCR4, potentially explaining the HIV inhibition. Deletion mapping of the NS5A protein found that an 85-aa region between amino acids 152 and 237 inhibits HIV-1 replication. Thus, GBV-C NS5A protein alters the cellular milieu necessary for HIV-1 replication and may provide a previously undescribed therapeutic approach for anti-HIV therapy.
authors.affiliation: Research Service and Department of Internal Medicine, Iowa City Veterans Affairs Medical Center and University of Iowa, 200 Hawkins Drive, Iowa City, IA 52242, USA. jinhua-xiang@uiowa.edu
authors.forename: Jinhua
authors.initials: J
authors.lastname: Xiang
authors.forename: James H
authors.initials: JH
authors.lastname: McLinden
authors.forename: Qing
authors.initials: Q
authors.lastname: Chang
authors.forename: Thomas M
authors.initials: TM
authors.lastname: Kaufman
authors.forename: Jack T
authors.initials: JT
authors.lastname: Stapleton
mesh_terms: D015496:CD4-Positive T-Lymphocytes / Q000502:physiology*; D054377:Chemokine CXCL12; D019743:Chemokines, CXC / Q000378:metabolism; D018178:Flaviviridae Infections; D029407:GB virus C / Q000235:genetics / Q000378:metabolism*; D015658:HIV Infections; D015497:HIV-1 / Q000502:physiology*; D006801:Humans; D019169:Jurkat Cells; D008969:Molecular Sequence Data; D019718:Receptors, CXCR4 / Q000378:metabolism; D017361:Viral Nonstructural Proteins / Q000235:genetics / Q000378:metabolism*; D014779:Virus Replication; D012324:RNA-Dependent RNA Polymerase
chemical_list: D054377:Chemokine CXCL12; D019743:Chemokines, CXC; D019718:Receptors, CXCR4; D017361:Viral Nonstructural Proteins; C515255:CXCL12 protein, human; C087036:NS-5 protein, hepatitis C virus; D012324:RNA-Dependent RNA Polymerase