New insights into Human Pegivirus-1 (HPgV-1) genotypes diversity in sub-Saharan Africa.

In the framework of a viral discovery research program using metagenomics, Human Pegivirus-1 reads (HPgV-1, formerly known as GBV-C) were detected in plasma pools of healthy blood donors from seven sub-Saharan African countries. For five of these countries, Mauritania, Mali, Niger, Burundi and Madagascar, no data about HPgV-1 genotypes was reported to date. To confirm our metagenomic findings and further investigate the genotype diversity and distribution of HPgV-1 in Africa, 400 blood donations from these five localities as well as from Cameroon, the Democratic Republic of Congo (DRC) and the Burkina Faso were screened with a RT-nested PCR targeting the viral 5'NCR region. Amplified products were sequenced, and the virus was genotyped by phylogenetic analysis. Out of the 400 plasma samples tested, 65 were positive for HPgV-1 RNA and 61 were successfully genotyped. Among these, 54 strains (88.5%) clustered with genotype 1, six (9.8%) with genotype 2 and one (1.6%) with genotype 5. Genotype 1 was observed in all countries studied, except in Madagascar, genotype 2 was detected in Mauritania and Madagascar, and genotype 5 in DRC. Overall, our results extend the geographic distribution of HPgV-1 in Africa and provide six additional nearly complete genomes. Considering that some HPgV-1 genotypes have been reported as potential predictive indicators of lower disease progression in HIV-1 infected subjects, further investigations should be conducted to better understand the positive impact, if any, of this virus.

Evidence for Within-Host Genetic Recombination among the Human Pegiviral Strains in HIV Infected Subjects.

The non-pathogenic Human Pegivirus (HPgV, formerly GBV-C/HGV), the most prevalent RNA virus worldwide, is known to be associated with reduced morbidity and mortality in HIV-infected individuals. Although previous studies documented its ubiquity and important role in HIV-infected individuals, little is known about the underlying genetic mechanisms that maintain high genetic diversity of HPgV within the HIV-infected individuals. To assess the within-host genetic diversity of HPgV and forces that maintain such diversity within the co-infected hosts, we performed phylogenetic analyses taking into account 229 HPgV partial E1-E2 clonal sequences representing 15 male and 8 female co-infected HIV patients from Hubei province of central China. Our results revealed the presence of eleven strongly supported clades. While nine clades belonged to genotype 3, two clades belonged to genotype 2. Additionally, four clades that belonged to genotype 3 exhibited inter-clade recombination events. The presence of clonal sequences representing multiple clades within the HIV-infected individual provided the evidence of co-circulation of HPgV strains across the region. Of the 23 patients, six patients (i.e., five males and one female) were detected to have HPgV recombinant sequences. Our results also revealed that while male patients shared the viral strains with other patients, viral strains from the female patients had restricted dispersal. Taken together, the present study revealed that multiple infections with divergent HPgV viral strains may have caused within-host genetic recombination, predominantly in male patients, and therefore, could be the major driver in shaping genetic diversity of HPgV.

Prevalence of human pegivirus (HPgV) infection in patients carrying HIV-1C or non-C in southern Brazil.

Previous studies have demonstrated that coinfection with HPgV is a protective factor for human immunodeficiency virus (HIV)-infected patients, leading to slower disease progression, and longer survival after established disease. The present study sought to estimate the prevalence of HPgV infection and associated risk factors in patients harboring C or non-C HIV-1 subtypes followed-up at HU-FURG, southern Brazil. Samples from 347 HIV-1-infected subjects were subjected to plasma RNA extraction, cDNA synthesis, HPgV RNA detection, and HIV-1 genotyping. The overall prevalence of HPgV RNA was 34%. Individuals aged 18-30 years had higher chances of infection compared with those 50 years or older (95%CI 1.18-52.36, P = 0.03). The number of sexual partner between one and three was a risk factor for HPgV infection (95%CI 1.54-10.23; P < 0.01), as well as the time since diagnosis of HIV-1 ≥ 11 years (95%CI 1.01-2.89; P = 0.04). Patients infected with HIV non-C subtypes had six times more chance of being HPgV-infected when compared to subtype C-infected subjects (95%CI 2.28-14.78; P < 0.01). This was the first study conducted in southern Brazil to find the circulation of HPgV. HIV/HPgV coinfection was associated with a longer survival among HIV+ patients. Of novelty, individuals infected by HIV non-C subtypes were more susceptible to HPgV infection. However, additional studies are needed to correlate the HIV-1 subtypes with HPgV infection and to clarify cellular and molecular pathways through which such associations are ruled. J. Med. Virol 88:2106-2114, 2016. © 2016 Wiley Periodicals, Inc.

Tropism of human pegivirus (formerly known as GB virus C/hepatitis G virus) and host immunomodulation: insights into a highly successful viral infection.

Human pegivirus (HPgV; originally called GB virus C/hepatitis G virus) is an RNA virus within the genus Pegivirus of the family Flaviviridae that commonly causes persistent infection. Worldwide, ~750 million people are actively infected (viraemic) and an estimated 0.75-1.5 billion people have evidence of prior HPgV infection. No causal association between HPgV and disease has been identified; however, several studies described a beneficial relationship between persistent HPgV infection and survival in individuals infected with human immunodeficiency virus. The beneficial effect appeared to be related to a reduction in host immune activation. HPgV replicates well in vivo (mean plasma viral loads typically >1×107 genome copies ml-1); however, the virus grows poorly in vitro and systems to study this virus are limited. Consequently, mechanisms of viral persistence and host immune modulation remain poorly characterized, and the primary permissive cell type(s) has not yet been identified. HPgV RNA is found in liver, spleen, bone marrow and PBMCs, including T- and B-lymphocytes, NK-cells, and monocytes, although the mechanism of cell-to-cell transmission is unclear. HPgV RNA is also present in serum microvesicles with properties of exosomes. These microvesicles are able to transmit viral RNA to PBMCs in vitro, resulting in productive infection. This review summarizes existing data on HPgV cellular tropism and the effect of HPgV on immune activation in various PBMCs, and discusses how this may influence viral persistence. We conclude that an increased understanding of HPgV replication and immune modulation may provide insights into persistent RNA viral infection of humans.

Downregulation of Cytokines and Chemokines by GB Virus C After Transmission Via Blood Transfusion in HIV-Positive Blood Recipients.

BACKGROUND: An association between GB virus C (GBV-C) and improved outcomes of human immunodeficiency virus (HIV) infection has been reported in HIV-positive individuals with active GBV-C coinfection. This study provides insights into the immune mechanisms underlying the protective role of GBV-C in HIV-infected patients. METHODS: The concentrations of 64 cytokines and chemokines were measured in plasma samples obtained from the Viral Activation Transfusion Study cohort before transfusion and longitudinally from 30 patients positive for both HIV and GBV-C (hereafter, "cases") and 30 patients positive for HIV and negative for GBV-C (hereafter, "controls"). RESULTS: Cases had lower HIV viral loads and higher CD4 T-cell counts than controls after acquisition of GBV-C infection. Most of the modulated cytokines and chemokines were reduced after GBV-C detection, including many proinflammatory cytokines, suggesting an overall antiinflammatory effect of GBV-C in HIV-positive subjects. Most pathways and functions of the measured cytokines were downregulated in cases, except cell death pathways, which were upregulated in various cell subsets in the 3 months after GBV-C detection. CONCLUSIONS: GBV-C has a protective effect, in part through a competition mechanism leading to decreased inflammation and improved HIV disease outcome in cases. Further studies are necessary to establish whether GBV-C may have deleterious effects on the host at the cellular level, including depleting the cells that are the targets of HIV.

Impact of GB virus C viraemia on clinical outcome in HIV-1-infected patients: a 20-year follow-up study.

OBJECTIVES: The impact of coexisting GB virus C (GBV-C) infection on the clinical course of HIV infection remains controversial. Early data from HIV-1 infected patients attending the Hannover Medical School in 2001 suggested prognostic benefit in GBV-C viraemic patients. The aim of this study was to evaluate patterns in long-term mortality and morbidity outcomes in this cohort. The impact of the introduction of antiretroviral therapy (ART) on the perceived benefits of GBV-C viraemia was subsequently investigated. METHODS: A retrospective follow-up analysis of data in this cohort was performed. GBV-C status (GBV-C RNA positive, antibodies against GBV-C envelope protein E2 or no evidence of GBV-C exposure) had been determined at enrolment, with several markers of HIV disease progression (such as viral load and CD4 cell count) being collated from 1993/1994, 2000 and 2012. These eras were chosen to reflect variations in treatment strategies within the cohort. In addition, mortality and HIV-related morbidity data were collated for all patients. RESULTS: Complete data were available for 156 of 197 patients (79%). In highly active antiretroviral therapy (HAART)-naïve patients, GBV-C RNA positivity conferred significant improvements in the course of HIV infection and mortality as well as lower rates of HIV-related diseases. E2 positivity alone conferred no significant advantage. With the advent of HAART, however, the benefits GBV-C RNA positivity disappeared. CONCLUSIONS: Although GBV-C coinfection appears to inherently improve morbidity and mortality in HIV-infected patients, modern HAART has eradicated these advantages. Evidence of synergy between GBV-C status and HAART response exists, with further studies examining the role of GBV-C in existing treatment de-escalation strategies being required.

[Interaction between HIV-1 and GB virus type-C during coinfection status]. / Interacción entre el virus de la inmunodeficiencia humana y el virus GB tipo-C durante el estado de co-infección.

The human immunodeficiency virus (HIV) infection is one of the most important problems in public health. It is estimated that 3 3 million people are infected around the world. HIV and GBV-C share the same transmission route, being frequent the co-infection. Since both viruses replicate in CD4+ lymphocytes, recent studies have described an interaction. Decreasing of HIV viral load and higher CD4 counts have been observed in co-infected patients, leading a better clinical outcome. Nevertheless, some epidemiological studies have shown contradictory results. Additionally, in vitro models report inhibition of HIV by E1, E2, NS3 and NS5A GBV-C proteins, resulting in a decreasing of p24 antigen. This review summarizes the principal findings about co-infection and mechanisms that have been proposed for HIV-1 inhibition.

Hepatitis viruses (other than hepatitis B and C viruses) as causes of hepatocellular carcinoma: an update.

Chronic hepatitis B and C virus infections are universally accepted as causes of hepatocellular carcinoma in humans. Hepatitis A and E viruses cause only acute self-limiting infections of the liver. Of the remaining hepatitis viruses - Delta hepatitis, hepatitis G (GB-C), TT and SEN - all have at some time been incriminated as causes of hepatocellular carcinoma. Delta hepatitis virus requires helper functions from hepatitis B virus to become invasive. Chronic Delta/hepatitis B viral co-infection runs a more severe course than that resulting from chronic hepatitis B virus infection alone, with progression to cirrhosis being more likely and more rapid. A substantial majority of the early studies did not find an increased incidence of hepatocellular carcinoma in co-infected individuals. But more recently, an increased incidence of the tumour has been recorded more often than no increase. Further studies are needed to draw a firm conclusion with regard to the hepatocarcinogenic effect of dual Delta/hepatitis B virus co-infection. With one exception, no published study (of 13) has incriminated chronic infection with hepatitis G virus as a cause of hepatocellular carcinoma. The dissenting study, published in 1999, was the only one performed in the United States. Fewer studies of the hepatocarcinogenic effect of TT virus have been performed. Apart from one study, published in 1999, no convincing evidence is available that supports a causal role for TT virus in hepatocarcinogenesis. The exception was in Japanese patients with high hepatitis C viral loads but independent of chronic hepatitis C virus infection. No evidence has been produced to indicate that SEN virus causes hepatocellular carcinoma.

Interacción entre el virus de la inmunodeficiencia humana y el virus GB tipo-C durante el estado de co-infección / Interaction between HIV-1 and GB virus type-C during coinfection status

The human immunodeficiency virus (HIV) infection is one of the most important problems in public health. It is estimated that 3 3 million people are infected around the world. HIV and GBV-C share the same transmission route, being frequent the co-infection. Since both viruses replicate in CD4+ lymphocytes, recent studies have described an interaction. Decreasing of HIV viral load and higher CD4 counts have been observed in co-infected patients, leading a better clinical outcome. Nevertheless, some epidemiological studies have shown contradictory results. Additionally, in vitro models report inhibition of HIV by E1, E2, NS3 and NS5A GBV-C proteins, resulting in a decreasing of p24 antigen. This review summarizes the principal findings about co-infection and mechanisms that have been proposed for HIV-1 inhibition.

La infección por el virus de la inmunodeficiencia humana (VIH) continúa siendo uno de los principales problemas en salud pública; se estima que existen actualmente más de 33 millones de personas infectadas en el mundo. El VIH y el virus GB tipo C (GBV-C) comparten la misma vía de transmisión, por lo que es frecuente encontrar individuos co-infectados. Estudios recientes han descrito un efecto inhibitorio asociado a disminución en la carga viral de VIH, altos recuentos de CD4 y mayor tiempo de sobrevida en pacientes co-infectados, resultando en un mejor pronóstico y menor progreso a SIDA; adicionalmente, estudios in vitro indican que las proteínas virales E1, E2, NS3 y NS5A del GBV-C estarían implicadas en la inhibición del VIH-1. En el presente artículo se revisan los principales aspectos de la co-infección, y se describen los mecanismos propuestos para la inhibición de la replicación del VIH-1 mediada por las proteínas virales del GBV-C.

Chimpanzee GB virus C and GB virus A E2 envelope glycoproteins contain a peptide motif that inhibits human immunodeficiency virus type 1 replication in human CD4⁺ T-cells.

GB virus type C (GBV-C) is a lymphotropic virus that can cause persistent infection in humans. GBV-C is not associated with any disease, but is associated with reduced mortality in human immunodeficiency virus type 1 (HIV-1)-infected individuals. Related viruses have been isolated from chimpanzees (GBV-Ccpz) and from New World primates (GB virus type A, GBV-A). These viruses are also capable of establishing persistent infection. We determined the nucleotide sequence encoding the envelope glycoprotein (E2) of two GBV-Ccpz isolates obtained from the sera of captive chimpanzees. The deduced GBV-Ccpz E2 protein differed from human GBV-C by 31 % at the amino acid level. Similar to human GBV-C E2, expression of GBV-Ccpz E2 in a tet-off human CD4(+) Jurkat T-cell line significantly inhibited the replication of diverse HIV-1 isolates. This anti-HIV-replication effect of GBV-Ccpz E2 protein was reversed by maintaining cells in doxycycline to reduce E2 expression. Previously, we found a 17 aa region within human GBV-C E2 that was sufficient to inhibit HIV-1. Although GBV-Ccpz E2 differed by 3 aa differences in this region, the chimpanzee GBV-C 17mer E2 peptide inhibited HIV-1 replication. Similarly, the GBV-A peptide that aligns with this GBV-C E2 region inhibited HIV-1 replication despite sharing only 5 aa with the human GBV-C E2 sequence. Thus, despite amino acid differences, the peptide region on both the GBV-Ccpz and the GBV-A E2 protein inhibit HIV-1 replication similar to human GBV-C. Consequently, GBV-Ccpz or GBV-A infection of non-human primates may provide an animal model to study GB virus-HIV interactions.

Intra-host diversity and emergence of unique GBV-C viral lineages in HIV infected subjects in central China.

GB virus C (GBV-C), which is highly prevalent among HIV/AIDS, seemed to slow the HIV disease progression. The HIV/GBV-C co-infected individuals may represent an interesting model for the investigation of the role played by HIV infection and/or the immune system in driving the evolution of the GBV-C viral populations. The present study investigated the prevalence and population dynamics of GB virus C in HIV infected individuals representing 13 geographic regions of Hubei Province of China. Approximately 37% of HIV-1 infected individuals were infected with GBV-C and genotype 3 is appeared to be predominant. Utilizing the 196 complete E2 nucleotide sequence data from 10 HIV/GBV-C infected individuals and employing coalescence based phylogenetic approaches; the present study has investigated the intra-host dynamics of GBV-C. The results revealed patient-specific unique GBV-C viral lineages and each viral lineage showed the evidence of rapid population expansion in respective HIV-1 infected patients, thus suggesting HIV-1 was unlikely to have been inhibiting effect on the GBV-C viral replication. GBV-C in all patients has experienced intense purifying selection, suggesting the GBV-C viral invasion and subsequent expansion within the HIV-1 infected hosts without any modification of the functional epitopes at their membrane protein. The finding of within host GBV-C recombinant sequences indicated recombination was one of the significant forces in the evolution and divergence of GBV-C.

GB virus C infection is associated with a reduced rate of reactivation of latent HIV and protection against activation-induced T-cell death.

BACKGROUND: GB virus C (GBV-C) coinfection is associated with reduced immune activation and a block in CD4(+) T-cell proliferation following interleukin-2 (IL-2) therapy in HIV-infected individuals. We examined peripheral blood mononuclear cells (PBMCs) from HIV-infected subjects with and without GBV-C viraemia to determine if GBV-C correlated with reactivation of latent HIV, T-cell proliferation or T-cell survival following in vitro activation with phytohaemagglutinin A and IL-2 (PHA/IL-2). METHODS: HIV-infected subjects whose HIV viral load was suppressed on combination antiretroviral therapy (cART) for >6 months were studied. PBMCs were cultured with and without PHA/IL-2 and monitored for HIV reactivation, proliferation and survival. GBV-C viraemia and in vitro replication were detected by real-time RT-PCR. HIV reactivation was determined by measuring HIV p24 antigen in culture supernatants. Proliferation was measured by counting viable cells and survival measured by flow cytometry. RESULTS: Of 49 HIV-infected individuals, 26 had GBV-C viraemia. Significantly less HIV reactivation and PBMC proliferation following in vitro activation with PHA/IL-2 was observed in samples from GBV-C viraemic subjects compared with non-viraemic controls. Following 5 weeks in culture, GBV-C replication was associated with preservation of CD4(+) and CD8(+) T-cells compared with non-viraemic controls. CONCLUSIONS: GBV-C appears to inhibit immune activation and IL-2 signalling pathways, which might contribute to a reduction in reactivation of latent HIV from cellular reservoirs. In addition, GBV-C viraemia was associated with a reduction in activation-induced T-cell death. GBV-C-associated T-cell effects could contribute to the observed protective effect of GBV-C coinfection in HIV-infected individuals.

Role of GB virus C in modulating HIV disease.

GB virus C (GBV-C) is a member of the Flaviviridae family and the most closely related human virus to HCV. However, GBV-C does not replicate in hepatocytes, but rather in lymphocytes. GBV-C has a worldwide distribution and is transmitted sexually, parenterally and through mother-to-child transmission. Thus, co-infection with HCV and HIV is common. Until now, no human disease has been associated with GBV-C infection. However, there are several reports of a beneficial effect of GBV-C on HIV disease progression in vivo. Different mechanisms to explain these observations have been proposed, including modification of antiviral cytokine production, HIV co-receptor expression, direct inhibition of HIV-1 entry, T-cell activation and Fas-mediated apoptosis. Further understanding of these mechanisms may open new strategies for the treatment of HIV/AIDS.

GB virus C: the good boy virus?

GB virus C (GBV-C) is a lymphotropic human virus discovered in 1995 that is related to hepatitis C virus (HCV). GBV-C infection has not been convincingly associated with any disease; however, several studies found an association between persistent GBV-C infection and improved survival in HIV-positive individuals. GBV-C infection modestly alters T cell homeostasis in vivo through various mechanisms, including modulation of chemokine and cytokine release and receptor expression, and by diminution of T cell activation, proliferation and apoptosis, all of which may contribute to improved HIV clinical outcomes. In vitro studies confirm these clinical observations and demonstrate an anti-HIV replication effect of GBV-C. This review summarizes existing data on potential mechanisms by which GBV-C interferes with HIV, and the research needed to capitalize on this epidemiological observation.

GBV-C: state of the art and future prospects.

The GB virus C is a common non-pathogenic virus, member of the Flaviviridae family with worldwide distribution. Favorable clinical course and reduced mortality among HIV-infected patients was demonstrated by several studies with patients co-infected with the GB virus C (GBV-C). This potential benefit of GBV-C has been demonstrated in the pre-HAART and post-HAART eras; however, this effect was not observed in all studies and the discrepancy may be due to changes during the course of HIV infection, characteristic of the cohort, and the degree of therapeutic response. The GBV-C has been found to decrease HIV replication in in vitro models, highlighting the interference of persistent GBV-C viremia. The mechanism of the beneficial effect of GBV-C appears to be mediated by changes in the cellular immune response, and elucidation of putative protective effects of GBV-C in HIV co-infection could potentially identify novel targets for anti-HIV agents.

Peptides derived from a distinct region of GB virus C glycoprotein E2 mediate strain-specific HIV-1 entry inhibition.

The nonpathogenic human GB virus C (GBV-C), a member of the Flaviviridae, is highly prevalent in individuals with HIV-1 infections or with parenteral and sexual risk factors. Long-term GBV-C viremia has been associated with better survival or improved diagnosis in several epidemiological studies. In a previous study we reported that the E2 glycoprotein of GBV-C interferes with HIV-1 entry in vitro. To address the question what region of the E2 protein is involved in suppression of HIV-1 replication, we performed an E2-derived peptide scanning and determined the HIV-inhibitory activity of each peptide in HIV replication assays. We demonstrate here that peptides representing the N-terminal part of the E2 protein from amino acids (aa) 29 to 72 are able to inhibit efficiently HIV-1 replication in vitro. In particular, the peptides P6-2 (representing the E2-region from aa 45 to 64) and P4762 (aa 37 to 64) showed the highest potency in HIV replication assays performed on TZM-bl cells with 50% inhibitory concentrations between 0.1 and 2 µM. However, primary HIV-1 isolates representing clades A to H showed a high variability in their sensitivity to E2 peptides. Pseudovirus inhibition assays revealed that the sensitivity is determined by the gp120/gp41 envelope proteins. Using HIV-1 BlaM-Vpr-based fusion assays, we demonstrate that the E2-derived peptides prevent HIV-1 binding or fusion, presumably via interaction with the HIV-1 particle. Together, these findings reveal a new mechanism of viral interference, suggesting that the envelope protein E2 of GBV-C target directly HIV-1 particles to avoid entry of these virions.

Influence of hepatitis G virus (GB virus C) on the prognosis of HIV-infected women.

This study was undertaken to evaluate the prevalence of GB virus C (GBV-C) viraemia and anti-E2 antibody, and to assess the effect of co-infection with GBV-C and HIV during a 10-year follow-up of a cohort of 248 HIV-infected women. Laboratory variables (mean and median CD4 counts, and HIV and GBV-C viral loads) and clinical parameters were investigated. At baseline, 115 women had past exposure to GBV-C: 57 (23%) were GBV-C RNA positive and 58 (23%) were anti-E2 positive. There was no statistical difference between the groups (GBV-C RNA + /anti-E2 - , GBV-C RNA - /anti-E2 + and GBV-C RNA - /anti-E2 - ) regarding baseline CD4 counts or HIV viral loads (P = 0.360 and 0.713, respectively). Relative risk of death for the GBV-C RNA + /anti-E2 - group was 63% lower than that for the GBV-C RNA - /anti-E2 - group. Multivariate analysis demonstrated that only HIV loads ≥ 100,000 copies/mL and AIDS-defining illness during follow-up were associated with shorter survival after AIDS development. It is likely that antiretroviral therapy (ART) use in our cohort blurred a putative protective effect related to the presence of GBV-C RNA.

GB virus C coinfection in advanced HIV type-1 disease is associated with low CCR5 and CXCR4 surface expression on CD4(+) T-cells.

BACKGROUND: Coinfection with the flavivirus GB virus C (GBV-C) is frequent in patients suffering from HIV type-1 (HIV-1) infection because of shared routes of transmission. GBV-C coinfection has been proposed to exert a beneficial influence on HIV-1 infection. In vitro studies demonstrated down-regulation of C-C chemokine receptor type 5 (CCR5) as a potential mechanism by which GBV-C modulates HIV-1 disease progression. We therefore studied surface expression of the two major HIV-1 coreceptors, CCR5 and CXC chemokine receptor type 4 (CXCR4), on CD4(+) and CD8(+) T-cells in 128 HIV-1-positive patients stratified with respect to their GBV-C status, immune function and highly active antiretroviral therapy (HAART) status in vivo. METHODS: GBV-C infection was studied in 128 HIV-1-infected patients by nested reverse transcriptase PCR. Fluorescence-activated cell sorting analysis was used to measure CCR5 and CXCR4 surface expression on CD4(+) and CD8(+) T-cells. RESULTS: GBV-C RNA replication was detected in 30% (38/128) of patients. In HIV-1-positive patients with advanced immunodeficiency, we found up-regulation of CCR5 surface expression on CD4(+) T-cells; however, in patients with GBV-C coinfection, no up-regulation of CCR5 CD4(+) T-cells was detected. Furthermore, CXCR4 surface expression was reduced in GBV-C-coinfected patients. These findings were independent of HAART status and HIV-1 viral load. HIV-1 coreceptor expression on CD8(+) T-cells was not altered in patients with GBV-C coinfection. CONCLUSIONS: GBV-C coinfection in HIV-1 disease leads to reduced expression of the two major HIV-1 coreceptors, CCR5 and CXCR4, on CD4(+) T-cells in patients at an advanced stage of immunodeficiency, providing a possible molecular explanation for the clinical benefit of GBV-C coinfection in late-stage HIV-1 disease.

Persistent replication of the GBV-C subgenomic replicons in Huh7 cells.

Studies of GB virus type C (GBV-C) replication in vitro have been limited because of poor growth of GBV-C in cell culture. In order to address the infection of GBV-C, two GBV-C subgenomic replicons (GBCrepEGFP and GBCrepTNF) were developed from a GBV-C full-length genomic cDNA. The viral replication, protein expression and the production of virus-like particles were evaluated in human hepatoma cell line Huh7. The results showed that the established GBCrepEGFP and GBCrepTNF replicons could be replicated autonomously and expressed in cell culture for at least 2 months and 1 month respectively. The replicon RNA could assemble RNA-containing structures in the HuhEH cells expressing GBV-C structural proteins. It suggests that a cell line supporting the replication of GBV-C was established. This replicon system might be used to understand better the biology of GBV-C.