Characterization of a Peptide Domain within the GB Virus C NS5A Phosphoprotein that Inhibits HIV Replication

BACKGROUND:GBV-C infection is associated with prolonged survival in HIV-infected people and GBV-C inhibits HIV replication in co-infection models. Expression of the GBV-C nonstructural phosphoprotein 5A (NS5A) decreases surface levels of the HIV co-receptor CXCR4, induces the release of SDF-1 and inhibits HIV replication in Jurkat CD4+ T cell lines. METHODOLOGY/PRINCIPAL FINDINGS:Jurkat cell lines stably expressing NS5A protein and peptides were generated and HIV replication in these cell lines assessed. HIV replication was significantly inhibited in all cell lines expressing NS5A amino acids 152-165. Substitution of an either alanine or glycine for the serine at position 158 (S158A or S158G) resulted in a significant decrease in the HIV inhibitory effect. In contrast, substituting a phosphomimetic amino acid (glutamic acid; S158E) inhibited HIV as well as the parent peptide. HIV inhibition was associated with lower levels of surface expression of the HIV co-receptor CXCR4 and increased release of the CXCR4 ligand, SDF-1 compared to control cells. Incubation of CD4+ T cell lines with synthetic peptides containing amino acids 152-167 or the S158E mutant peptide prior to HIV infection resulted in HIV replication inhibition compared to control peptides. CONCLUSIONS/SIGNIFICANCE:Expression of GBV-C NS5A amino acids 152-165 are sufficient to inhibit HIV replication in vitro, and the serine at position 158 appears important for this effect through either phosphorylation or structural changes in this peptide. The addition of synthetic peptides containing 152-167 or the S158E substitution to Jurkat cells resulted in HIV replication inhibition in vitro. These data suggest that GBV-C peptides or a peptide mimetic may offer a novel, cellular-based approach to antiretroviral therapy

Effect of GB virus C on response to antiretroviral therapy in HIV-infected Brazilians

ObjectivesGB virus C (GBV-C) infection is associated with delayed mortality in HIV-infected people in most, but not all, studies. Previous investigations of the effect of GBV-C viraemia on response to antiretroviral therapy (ART) were inconclusive. To determine the effect of GBV-C on ART, we retrospectively analysed plasma samples taken from patients in a prospective randomized clinical trial of ART in HIV-positive Brazilians.MethodsGBV-C viraemia was characterized by testing stored serum samples from 175 participants by reverse transcriptase-polymerase chain reaction (RT-PCR). Subjects were randomized to receive indinavir (n=59), zidovudine and lamivudine (n=58), or zidovudine, lamivudine and indinavir (n=58). the effect of GBV-C viraemia on the average change in HIV viral load and CD4 count following initiation of therapy was evaluated in a multiple regression analysis.ResultsThe prevalence of GBV-C viraemia was similar to that observed in previous studies (24%). HIV viral load decreased following ART to a significantly greater extent in patients with GBV-C viraemia (by 0.48 log(10) HIV-1 RNA copies/mL, P=0.009, adjusting for age, ART group, and baseline CD4 count). Although there was no significant difference in change in CD4 count between individuals with and without GBV-C viraemia overall, CD4 counts were higher following 48 weeks of therapy in GBV-C viraemic individuals receiving the least potent ART regimen (zidovudine and lamivudine) compared with those without GBV-C infection.ConclusionsGBV-C viraemia is associated with an enhanced reduction of HIV viral load in response to ART. in this study of treatment-naive individuals during 48 weeks of follow up, patients with GBV-C viraemia had reductions in HIV viral load that were approximately 0.5 log copies/mL greater than those found in patients without GBV-C viraemia. This is similar to reductions observed with nucleoside reverse transcriptase inhibitors.Univ Iowa, Dept Internal Med, Roy & Lucille Carver Coll Med, Iowa City, IA 52242 USAIowa City Vet Adm, Med Ctr, Iowa City, IA USAUniversidade Federal de São Paulo, Paulista Sch Med, Div Infect Dis, São Paulo, BrazilUniv Iowa, Coll Publ Hlth, Dept Biostat, Iowa City, IA USAUniversidade Federal de São Paulo, Paulista Sch Med, Div Infect Dis, São Paulo, BrazilWeb of Scienc

Effect of primer selection on estimates of GB virus C (GBV-C) prevalence and response to antiretroviral therapy for optimal testing for GBV-C viremia (vol 44, pg 3105, 2006)

Univ Iowa, Dept Internal Med, Roy & Lucille Carver Coll Med, Iowa City, IA 52242 USAIowa City Vet Adm Med Ctr, Iowa City, IA USAUniversidade Federal de São Paulo, Paulista Sch Med, Div Infect Dis, São Paulo, BrazilUniv Iowa, Coll Publ Hlth, Dept Biostat, Iowa City, IA USARoche Diagnost GmbH, Penzberg, GermanyRoche Diagnost GmbH, Mannheim, GermanyNIAID, Epidemiol Branch, Div Aids, NIH,Dept Hlth & Human Serv, Bethesda, MD 20892 USAJohns Hopkins Univ, Bloomberg Sch Publ Hlth, Baltimore, MD USAUniversidade Federal de São Paulo, Paulista Sch Med, Div Infect Dis, São Paulo, BrazilWeb of Scienc

Effect of Primer Selection on Estimates of GB Virus C (GBV-C) Prevalence and Response to Antiretroviral Therapy for Optimal Testing for GBV-C Viremia

GB virus C (GBV-C; also called hepatitis G virus) is a common cause of infection associated with prolonged survival among HIV-infected individuals. The prevalences of GBV-C viremia vary widely in different studies, and there has been poor agreement among different laboratories performing GBV-C RNA detection in quality control studies. To determine the optimal method of measuring GBV-C RNA in clinical samples, samples obtained from 939 HIV-infected subjects were studied using reverse transcription (RT)-PCR methods amplifying four separate regions of the GBV-C genome. Primers amplifying the E2 coding region were 100% specific; however, their sensitivity was only 76.6%. In contrast, primers amplifying three additional conserved regions of the GBV-C genome (the 5′ nontranslated region and the nonstructural protein-coding regions 3 and 5A) were more sensitive but produced higher rates of false-positive results. Using low-specificity primer sets influenced the significance of association between GBV-C viremia and response to antiretroviral therapy. Using a quantitative GBV-C RNA method, the GBV-C RNA concentration did not correlate with baseline or set point HIV RNA levels; however, a correlation between negative, low, and high GBV-C RNA levels and increasing reduction in HIV RNA following antiretroviral therapy was observed. Subjects with both GBV-C E2 antibody and viremia had significantly lower GBV-C RNA levels than did viremic subjects without E2 antibody. These studies demonstrate that accurate detection of GBV-C RNA by nested RT-PCR requires the use of primers representing multiple genome regions. Analyses based on testing with single primers do not lead to reliable conclusions about the association between GBV-C infection and clinical outcomes