Inhibition of HIV-1 replication by GB virus C infection through increases in RANTES, MIP-1alpha, MIP-1beta, and SDF-1

Short-term antiretroviral therapy may not correct the dysregulations of plasma virome and cytokines induced by HIV-1 infection

An expansion of plasma anelloviruses and dysregulation of inflammation was associated with HIV-1 infection. However, how antiretroviral therapy (ART) affects the dynamics of plasma virome and cytokine profile remains largely unknown. To characterize the dynamics of plasma virome and cytokines in HIV-1-infected individuals before and during the first year of ART, a cohort of 26 HIV-1-infected individuals and 19 healthy controls was recruited. Blood samples were collected and subjected to metagenomic analysis and the measurement of 27 cytokines. Metagenomic analysis revealed an increased abundance and prevalence of human pegivirus type 1 (HPgV-1) and a slightly decreased diversity and abundance of anellovirus in plasma of HIV-1-infected individuals after ART. No obvious impact was observed on other plasma commensal viruses. Increased abundance and prevalence of HPgV-1 were further confirmed by RT-qPCR assay in a larger cohort of 114 HIV-1-infected individuals. Notably, most dysregulated cytokines were not fully restored by ART, with extremely abnormal levels of IL-10, GM-CSF, VEGF, and eotaxin, and a significantly increased level of plasma I-FABP. Anelloviruses showed significantly negative correlations with other commensal viruses except HPgV-1 but had positive correlations with several anti-inflammatory and Th1 cytokines. These results suggest that short-term ART may not significantly correct the virome and cytokine dysregulations induced by HIV-1 infection. The results highlight a need for further investigation into the long-term effects of ART on virome and cytokine profiles in HIV-1-infected individuals.

Co-Infections and Superinfections between HIV-1 and Other Human Viruses at the Cellular Level

Co-infection or superinfection of the host by two or more virus species is a common event, potentially leading to viral interference, viral synergy, or neutral interaction. The simultaneous presence of two or more viruses, even distantly related, within the same cell depends upon viral tropism, i.e., the entry of viruses via receptors present on the same cell type. Subsequently, productive infection depends on the ability of these viruses to replicate efficiently in the same cellular environment. HIV-1 initially targets CCR5-expressing tissue memory CD4+ T cells, and in the absence of early cART initiation, a co-receptor switch may occur, leading to the infection of naïve and memory CXCR4-expressing CD4+ T cells. HIV-1 infection of macrophages at the G1 stage of their cell cycle also occurs in vivo, broadening the possible occurrence of co-infections between HIV-1 and other viruses at the cellular level. Moreover, HIV-1-infected DCs can transfer the virus to CD4+ T cells via trans-infection. This review focuses on the description of reported co-infections within the same cell between HIV-1 and other human pathogenic, non-pathogenic, or low-pathogenic viruses, including HIV-2, HTLV, HSV, HHV-6/-7, GBV-C, Dengue, and Ebola viruses, also discussing the possible reciprocal interactions in terms of virus replication and virus pseudotyping.

Interplay between HIV and Human Pegivirus (HPgV) Load in Co-Infected Patients: Insights from Prevalence and Genotype Analysis

Human pegivirus (HPgV) is transmitted through sexual or parenteral exposure and is common among patients receiving blood products. HPgV is associated with lower levels of human immunodeficiency virus (HIV) RNA and better survival among HIV-infected patients. This study aimed to investigate the prevalence of HPgV and determine its subtypes in HIV-infected individuals living in Istanbul, which has the highest rate of HIV infection in Türkiye. Total RNA extraction from plasma, cDNA synthesis, and nested PCR were performed for HPgV on plasma samples taken from 351 HIV-1-infected patients. The HPgV viral load was quantified on HPgV-positive samples. HPgV genotyping was performed by sequencing the corresponding amplicons. In the present study, the overall prevalence of HPgV RNA in HIV-infected patients was 27.3%. HPgV subtypes 1, 2a, and 2b were found, with subtype 2a being the most frequent (91.6%). Statistical analysis of HIV-1 viral load on HPgV viral load showed an opposing correlation between HIV-1 and HPgV loads. In conclusion, these data show that HPgV infection is common among HIV-positive individuals in Istanbul, Türkiye. Further comprehensive studies are needed to clarify both the cellular and molecular pathways of these two infections and to provide more information on the effect of HPgV on the course of the disease in HIV-infected individuals.

Human Pegivirus Type 1: A Common Human Virus That Is Beneficial in Immune-Mediated Disease?

Two groups identified a novel human flavivirus in the mid-1990s. One group named the virus hepatitis G virus (HGV) and the other named it GB Virus type C (GBV-C). Sequence analyses found these two isolates to be the same virus, and subsequent studies found that the virus does not cause hepatitis despite sharing genome organization with hepatitis C virus. Although HGV/GBV-C infection is common and may cause persistent infection in humans, the virus does not appear to directly cause any other known disease state. Thus, the virus was renamed “human pegivirus 1” (HPgV-1) for “persistent G” virus. HPgV-1 is found primarily in lymphocytes and not hepatocytes, and several studies found HPgV-1 infection associated with prolonged survival in people living with HIV. Co-infection of human lymphocytes with HPgV-1 and HIV inhibits HIV replication. Although three viral proteins directly inhibit HIV replication in vitro, the major effects of HPgV-1 leading to reduced HIV-related mortality appear to result from a global reduction in immune activation. HPgV-1 specifically interferes with T cell receptor signaling (TCR) by reducing proximal activation of the lymphocyte specific Src kinase LCK. Although TCR signaling is reduced, T cell activation is not abolished and with sufficient stimulus, T cell functions are enabled. Consequently, HPgV-1 is not associated with immune suppression. The HPgV-1 immunomodulatory effects are associated with beneficial outcomes in other diseases including Ebola virus infection and possibly graft-versus-host-disease following stem cell transplantation. Better understanding of HPgV-1 immune escape and mechanisms of inflammation may identify novel therapies for immune-based diseases.

Tissue presentation of human pegivirus infection in liver transplanted recipients

Human pegivirus-1 (HPgV-1) is known for its protective role in HIV co-infected individuals. This immunomodulatory effect raised questions concerning the possible role of HPgV-1 infection and the risk of rejection in liver transplanted patients. We aimed to evaluate the possible protective effect of HPgV-1 on graft outcome of liver transplanted patients. A total of 283 patients were recruited. Formalin-fixed paraffin-embedded tissue samples were collected from the explanted liver. HBV-DNA, HCV-RNA, and HPgV-1-RNA were determined using PCR and multiplex RT-PCR assays. The clinical course of patients including the occurrence of acute cellular rejection was compared between HPgV-1-infected vs. uninfected patients. HBV-DNA, HCV-RNA and HPgV-1-RNA were detected in 42.6%, 4.9%, and 7.8% of samples, respectively. None of the HPgV-1-infected patients experienced graft rejection. Group LASSO logistic regression revealed that HPgV-1 infection was the only factor which significantly reduced the odds of graft rejection (OR = 0.5, 95% CI = 0.29-0.89). No significant association was found between the presence of HPgV-1 with HBV and HCV infections. The lack of graft rejection in HPgV-1-infected liver transplanted patients might indicate a possible role of this virus for graft surveillance. Since these are still preliminary findings, prospective studies should further elucidate the role of HPgV-1 in liver transplantation outcomes.

Review of human pegivirus: Prevalence, transmission, pathogenesis, and clinical implication

Human pegivirus (HPgV-1), previously known as GB virus C (GBV-C) or hepatitis G virus (HGV), is a single-stranded positive RNA virus belonging to the genus Pegivirus of the Flaviviridae family. It is transmitted by percutaneous injuries (PIs), contaminated blood and/or blood products, sexual contact, and vertical mother-to-child transmission. It is widely prevalent in general population, especially in high-risk groups. HPgV-1 viremia is typically cleared within the first 1–2 years of infection in most healthy individuals, but may persist for longer periods of time in immunocompromised individuals and/or those co-infected by other viruses. A large body of evidences indicate that HPgV-1 persistent infection has a beneficial clinical effect on many infectious diseases, such as acquired immunodeficiency syndrome (AIDS) and hepatitis C. The beneficial effects seem to be related to a significant reduction of immune activation, and/or the inhabitation of co-infected viruses (e.g. HIV-1). HPgV-1 has a broad cellular tropism for lymphoid and myeloid cells, and preferentially replicates in bone marrow and spleen without cytopathic effect, implying a therapeutic potential. The paper aims to summarize the natural history, prevalence and distribution characteristics, and pathogenesis of HPgV-1, and discuss its association with other human viral diseases, and potential use in therapy as a biovaccine or viral vector.

Human pegivirus type 1 infection in Asia-A review of the literature

The human pegivirus type 1 (HPgV-1)-as known as hepatitis G virus and GB virus C-is a common single-stranded RNA flavivirus. Because few studies have demonstrated an association between HPgV-1 infection and disease, screening for HPgV-1 is not performed routinely. Nonetheless, a beneficial impact of HPgV-1 infection on HIV disease progression has been reported in multiple studies. Given the burden of HIV in Asia and the complex interactions between viral co-infections and the host, we provide a comprehensive overview of the existing data from Asia on HPgV-1 infection, including the prevalence and circulating genotypes in all Asian countries with data reported. This review highlights the research conducted thus far and emphasizes the need for additional studies on HPgV-1 across the Asian continent.

Human pegivirus (HPgV, GBV-C) RNA in volunteer blood donors from a public hemotherapy service in Northern Brazil

BACKGROUND

Human pegivirus (HPgV)-formerly known as GBV-C-is a member of the Flaviviridae family and belongs to the species Pegivirus C. It is a non-pathogenic virus and is transmitted among humans mainly through the exposure to contaminated blood and is often associated with human immunodeficiency virus (HIV) infection, among other viruses. This study aimed to determine the prevalence of HPgV viremia, its association with HIV and clinical epidemiological factors, as well as the full-length sequencing and genome characterization of HPgV recovered from blood donors of the HEMOPA Foundation in Belém-PA-Brazil.

METHODS

Plasma samples were obtained from 459 donors, tested for the presence of HPgV RNA by the RT-qPCR. From these, a total of 26 RT-qPCR positive samples were submitted to the NGS sequencing approach in order to obtain the full genome. Genome characterization and phylogenetic analysis were conducted.

RESULTS

The prevalence of HPgV was 12.42%. We observed the highest prevalences among donors aged between 18 and 30 years old (16.5%), with brown skin color (13.2%) and men (15.8%). The newly diagnosed HIV-1 prevalence was 26.67%. The HPgV genotype 2 (2a and 2b) was identified. No data on viral load value was found to corroborate the protective effect of HPgV on HIV evolution.

CONCLUSIONS

This study provided information regarding the HPgV infection among blood donors from HEMOPA Foundation. Furthermore, we genetically characterized the HPgV circulating strains and described by the first time nearly complete genomes of genotype 2 in Brazilian Amazon.

Human Pegivirus Infection and Lymphoma Risk: A Systematic Review and Meta-analysis

BACKGROUND

Human pegivirus (HPgV) is a single-strand RNA virus belonging to the Flaviviridae. Although no definitive association between HPgV infection and disease has been identified, previous studies have suggested an association of HPgV viremia with risk of lymphomas.

METHODS

We conducted a systematic review and meta-analysis, including 1 cohort study and 14 case-control studies, assessing the association of HPgV viremia with adult lymphomas. Odds ratios (ORs) and 95% confidence intervals (CIs) were calculated using a random-effects model, overall and by geographic region and lymphoma subtype.

RESULTS

The overall OR for lymphoma was 2.85 (95% CI, 1.98-4.11), with statistically significantly elevated ORs observed in 8 of 15 studies. There was a small amount of heterogeneity among studies (I2 = 28.9%; Q = 18.27, P = .16), and the funnel plot provided no evidence for publication bias. The strongest association with lymphoma risk was observed for studies from Southern Europe (OR, 5.68 [95% CI, 1.98-16.3]), whereas weaker ORs (with 95% CIs) were observed for studies from North America (2.24 [1.76-2.85]), Northern Europe (2.90 [.45-18.7), and the Middle East (2.51 [.87-7.27]), but all of similar magnitude. Participants with HPgV viremia had statistically significantly increased risks (OR [95% CI]) for developing diffuse large B-cell (3.29 [1.63-6.62]), follicular (3.01 [1.95-4.63]), marginal zone (1.90 [1.13-3.18]), and T-cell (2.11 [1.17-3.89]) lymphomas, while the risk for Hodgkin lymphoma (3.53 [.48-25.9]) and chronic lymphocytic leukemia (1.45 [.45-4.66]) were increased but did not achieve statistical significance.

CONCLUSIONS

This meta-analysis supports a positive association of HPgV viremia with lymphoma risk, overall and for the major lymphoma subtypes.

HIV-HBV and HIV-HCV Coinfection and Liver Cancer Development

Liver diseases that are caused by the hepatitis B virus (HBV) and hepatitis C virus (HCV), including cirrhosis and hepatocellular carcinoma (HCC), have become increasingly important in patients infected with the human immunodeficiency virus (HIV) as their life expectancy is getting longer with successful anti-HIV therapy. Due to their shared transmission routes, dual infection by HIV and HBV or HIV and HCV, and triple infection by all three viruses are fairly common and affect millions of people worldwide. Whereas the immunodeficiency caused by HIV enhances the likelihood of HBV and HCV persistence, hepatotoxicity associated with anti-HIV therapy can worsen the liver diseases associated with HBV or HCV persistence. Evidence suggests HIV infection increases the risk of HBV- or HCV-associated HCC risk although the precise mechanisms of enhanced hepatocarcinogenesis remain to be fully elucidated. Recent success in curing HCV infection, and the availability of therapeutic options effective in long-term suppression of both HIV and HBV replication, bring hope, fortunately, to those who are coinfected but also highlight the need for judicious selection of antiviral therapies.

Molecular and Clinical Profiles of Human Pegivirus Type 1 Infection in Individuals Living with HIV-1 in the Extreme South of Brazil

Human pegivirus type 1 (HPgV-1) infection has been associated with a beneficial effect on the prognosis of human immunodeficiency virus type 1 (HIV-1)-coinfected individuals. However, the mechanisms involved in this protection are not yet fully elucidated. To date, circulating HPgV-1 genotypes in HIV-1-infected individuals have not yet been identified in the extreme south of Brazil. The present study aimed to determine the genotypic circulation of HPgV-1 and the influence of HPgV-1 status and persistence time on the evolution of HIV-1 infection. A retrospective cohort of 110 coinfected individuals was analyzed. Samples were subjected to viral RNA extraction, cDNA synthesis, nested PCR, and genotyping. Genotypes 1 (2.8%), 2 (47.9% of subtype 2a and 42.3% of subtype 2b), and 3 (7%) were identified. In antiretroviral treatment-naïve subjects HPgV-1 subtype 2b was associated with lower HIV-1 viral load (VL) rates (p = 0.04) and higher CD4+ T-cell counts (p = 0.03) than was subtype 2a, and the positivity for HPgV-1 was associated with higher CD4+ T-cell counts (p = 0.02). However, there was no significant difference in HIV-1 VL between HPgV-1-positive and HPgV-1-negative subjects (p = 0.08). There was no significant association between the different groups in HPgV-1 persistence and median HIV-1 VL (p = 0.66) or CD4+ T-cell counts (p = 0.15). HPgV-1 subtype 2b is associated with better prognosis of HIV-1 infection. Although HPgV-1 infection is persistent, our data suggest that the time of infection does not influence HIV-1 VL or CD4+ T-cell counts in coinfected subjects.

The secretory phenotype of senescent astrocytes isolated from Wistar newborn rats changes with anti-inflammatory drugs, but does not have a short-term effect on neuronal mitochondrial potential

In the central nervous system (CNS), senescent astrocytes have been associated with neurodegeneration. Senescent cells secrete a complex mixture of pro-inflammatory factors, which are collectively called Senescence Associated Secretory Phenotype (SASP). The SASP components can vary depending on the cell type, senescence inducer and time. The SASP has been mainly studied in fibroblasts and epithelial cells, but little is known in the context of the CNS. Here, the SASP profile in senescent astrocytes isolated from Wistar newborn rats induced to senescence by oxidative stress or by proteasome inhibition was analyzed. Senescent astrocytes secreted predominantly chemokines and IL-1α, but no IL-6. The effect of the anti-inflammatory drugs, sulforaphane (SFN) and dehydroepiandrosterone (DHEA), on the SASP profile was evaluated. Our results showed that SFN and DHEA decreased IL-1α secretion while increasing IL-10, thus modifying the SASP to a less anti-inflammatory profile. Primary neurons were subjected to the conditioned media obtained from drug-treated senescent astrocytes, and their mitochondrial membrane potential was evaluated.

Hormonal influence on HIV-1 transmission in the female genital tract: New insights from systems biology

Although anti-retroviral treatments have significantly slowed down the spread of the HIV-1 pandemic, approximately 2 million new infections occur every year. The majority of new infections are in sub-Saharan Africa where rates of infection are much higher in women than men. Young women are disproportionately affected and have higher susceptibility to HIV-1. The complex interactions between HIV-1 and the female genital tract (FGT) and the mechanisms regulating susceptibility in women remain incompletely understood. In this review, we focus on the current understanding of the acute events that occur in the FGT following HIV-1 exposure with a particular focus on the effect of endogenous and exogenous sex hormones on HIV-1 susceptibility. We highlight the contribution of the recent transcriptomic and proteomic studies in providing new insights.

Human Pegivirus infection and lymphoma risk and prognosis: a North American study

We evaluated the association of Human Pegivirus (HPgV) viraemia with risk of developing lymphoma, overall and by major subtypes. Because this virus has also been associated with better prognosis in the setting of co-infection with human immunodeficiency virus, we further assessed the association of HPgV with prognosis. We used risk factor data and banked plasma samples from 2094 lymphoma cases newly diagnosed between 2002 and 2009 and 1572 frequency-matched controls. Plasma samples were tested for HPgV RNA by reverse transcription polymerase chain reaction (RT-PCR), and those with RNA concentrations <5000 genome equivalents/ml were confirmed using nested RT-PCR methods. To assess the role of HPgV in lymphoma prognosis, we used 2948 cases from a cohort study of newly diagnosed lymphoma patients (included all cases from the case-control study). There was a positive association of HPgV viraemia with risk of lymphoma overall (Odds ratio = 2·14; 95% confidence interval [CI] 1·63-2·80; P < 0·0001), and for all major subtypes except Hodgkin lymphoma and chronic lymphocytic leukaemia/small lymphocytic lymphoma, and this was not confounded by other lymphoma risk factors. In contrast, there was no association of HPgV viraemia with event-free survival (Hazard ratio [HR] = 1·00; 95% CI 0·85-1·18) or overall survival (HR = 0·97; 95% CI 0·79-1·20) for lymphoma overall, or any of the subtypes. These data support the hypothesis for a role of HPgV in the aetiology of multiple lymphoma subtypes.

Human pegivirus (HPgV) infection in sub-Saharan Africa-A call for a renewed research agenda

The human pegivirus (HPgV)-formerly GB virus C-has a beneficial impact on HIV disease progression that has been described in multiple studies. Given the high prevalence of HIV in sub-Saharan Africa and the continuing need to suppress HIV replication, this review provides a comprehensive overview of the existing data on HPgV infection in sub-Saharan Africa, with a particular focus on studies of prevalence and the circulating HPgV genotypes. This review also highlights the need for additional studies of HPgV conducted on the African continent and proposes a research agenda for evaluation of HPgV.

Transgenic mice expressing HIV-1 envelope protein gp120 in the brain as an animal model in neuroAIDS research

HIV-1 infection causes injury to the central nervous system (CNS) and is often associated with neurocognitive disorders. One model for brain damage seen in AIDS patients is the transgenic (tg) mouse expressing a soluble envelope protein gp120 of HIV-1 LAV in the brain in astrocytes under the control of the promoter of glial fibrillary acidic protein. These GFAP-gp120tg mice manifest several key neuropathological features observed in AIDS brains, such as decreased synaptic and dendritic density, increased numbers of activated microglia, and pronounced astrocytosis. Several recent studies show that brains of GFAP-gp120tg mice and neurocognitively impaired HIV patients share also a significant number of differentially regulated genes, activation of innate immunity and other cellular signaling pathways, disturbed neurogenesis, and learning deficits. These findings support the continued relevance of the GFAP-gp120tg mouse as a useful model to investigate neurodegenerative mechanisms and develop therapeutic strategies to mitigate the consequences associated with HIV infection of the CNS, neuroAIDS, and HAND.

Cytokine/chemokine expression associated with Human Pegivirus (HPgV) infection in women with HIV

A beneficial impact of the Human Pegivirus (HPgV)-formerly called GB virus C (GBV-C)-on HIV disease progression has been reported previously. One possible mechanism by which HPgV inhibits HIV replication is an alteration of the cytokine/chemokine milieu. Their expression has not been specifically evaluated in women despite their influence on disease progression and the possibility of gender-based differences in expression. Moreover, the impact of HPgV genotype on cytokine/chemokine expression is unknown. Sera levels of IL-2, IL-4, IL-7, IL-8, IL-10, IL-12p70, IL-13, IFNγ, TNFα, IP-10, MIP-1α, MIP-1β, and TGF-β₁ were quantified in 150 HIV-positive women based on HPgV RNA status. Cytokines/chemokines with detection rates of at least 50% included IL-2, IL-4, IL-8, IL-10, IL-12p70, IFNγ, TNFα, IP-10, MIP-1α, MIP-1β, and TGF-β₁ . Absolute values were significantly higher for HPgV positive compared to HPgV negative women for IL-7, IL-13, IL-12p70, and IFNγ. Absolute values were significantly lower for HPgV positive women for IL-4, IL-8, TGF-β₁ , and IP-10. IFNγ values were higher for HPgV genotype 2 than for genotype 1 (P = 0.036). Further study of cytokine/chemokine regulation by HPgV may ultimately lead to the development of novel therapeutic agents to treat HIV infection and/or the design of vaccine strategies that mimic the "protective" effects of HPgV replication.

GBV-C/HIV-1 coinfection is associated with low HIV-1 viral load and high CD4+ T lymphocyte count

GB virus C (GBV-C) is a lymphotropic virus with a low level or non-existent replication in the liver. The interaction between HIV-1 and GBV-C apparently reduces the progression of HIV-1 infection to AIDS and improves the quality of life of HIV-1 infected individuals. A cross-sectional study was established to determine the possible effect of HIV-1/GBV-C coinfection on HIV-1 viral load and CD4⁺ T lymphocyte counts. Samples from 313 HIV-1 infected persons from the Virus Laboratory of the Federal University of Pará as well as demographic and clinical information were obtained from medical records. This study used a nested PCR method to determine GBV-C viremia. The prevalence of HIV-1/GBV-C coinfection was 17%. There were no significant differences in the distribution according to age, sex or ethnicity between the groups. The differences in HIV-1 viral load and CD4⁺ T lymphocyte count between the HIV-1 and HIV-1/GBV-C groups were highly significant, indicating that coinfection results in lower viral loads and higher CD4⁺ T lymphocyte counts compared to HIV-1 mono-infection. The results indicate a protective effect among coinfected individuals.

IFNβ Protects Neurons from Damage in a Murine Model of HIV-1 Associated Brain Injury

Infection with human immunodeficiency virus-1 (HIV-1) causes brain injury. Type I interferons (IFNα/β) are critical mediators of any anti-viral immune response and IFNβ has been implicated in the temporary control of lentiviral infection in the brain. Here we show that transgenic mice expressing HIV-1 envelope glycoprotein 120 in their central nervous system (HIVgp120tg) mount a transient IFNβ response and provide evidence that IFNβ confers neuronal protection against HIVgp120 toxicity. In cerebrocortical cell cultures, neuroprotection by IFNβ against gp120 toxicity is dependent on IFNα receptor 1 (IFNAR1) and the β-chemokine CCL4, as IFNAR1 deficiency and neutralizing antibodies against CCL4, respectively, abolish the neuroprotective effects. We find in vivo that IFNβ mRNA is significantly increased in HIVgp120tg brains at 1.5, but not 3 or 6 months of age. However, a four-week intranasal IFNβ treatment of HIVgp120tg mice starting at 3.5 months of age increases expression of CCL4 and concomitantly protects neuronal dendrites and pre-synaptic terminals in cortex and hippocampus from gp120-induced damage. Moreover, in vivo and in vitro data suggests astrocytes are a major source of IFNβ-induced CCL4. Altogether, our results suggest exogenous IFNβ as a neuroprotective factor that has potential to ameliorate in vivo HIVgp120-induced brain injury.

GB virus type C E2 protein inhibits human immunodeficiency virus type 1 Gag assembly by downregulating human ADP-ribosylation factor 1

GB virus type C (GBV-C) glycoprotein E2 protein disrupts HIV-1 assembly and release by inhibiting Gag plasma membrane targeting, however the mechanism by which the GBV-C E2 inhibits Gag trafficking remains unclear. In the present study, we identified ADP-ribosylation factor 1 (ARF1) contributed to the inhibitory effect of GBV-C E2 on HIV-1 Gag membrane targeting. Expression of GBV-C E2 decreased ARF1 expression in a proteasomal degradation-dependent manner. The restoration of ARF1 expression rescued the HIV-1 Gag processing and membrane targeting defect imposed by GBV-C E2. In addition, GBV-C E2 expression also altered Golgi morphology and suppressed protein traffic through the secretory pathway, which are all consistent with a phenotype of disrupting the function of ARF1 protein. Thus, our results indicate that GBV-C E2 inhibits HIV-1 assembly and release by decreasing ARF1, and may provide insights regarding GBV-C E2's potential for a new therapeutic approach for treating HIV-1.

Prevalence and genotypes of GBV-C and its associations with HIV infection among persons who inject drugs in Eastern Europe

We aimed to determine the rate of GBV-C viremia, seropositivity, and genotypes among people who inject drugs (PWID) and healthy volunteers in Estonia and to evaluate associations between GBV-C and sociodemographic factors, intravenous drug use, co-infections. The study included 345 Caucasian PWID and 118 healthy volunteers. The presence of GBV-C RNA (viremia) was determined by reverse transcriptase-nested PCR in 5' long terminal repeat. PCR products were sequenced and genotyped by phylogenetic analysis. GBV-C seropositivity was determined by ELISA. One third of PWID (114/345) and 6% (7/118) of healthy volunteers (OR = 7.8, 95% CI = 3.5-20.5, P < 0.001) were GBV-C viremic. In PWID group, 79% of sequences belonged to subtype 2a, 19% to subtype 2b, and two remained unclassified. In healthy volunteers, six out of seven sequences belonged to subtype 2a and one to subtype 2b. We found HIV+ PWID to have two times increased odds of being GBV-C viremic compared to HIV- PWID (62% vs. 38%; OR = 2.13, 95% CI = 1.34-3.36, P = 0.001). In addition, odds of being GBV-C viremic decreased with increasing age (OR = 0.94, 95% CI = 0.90-0.98, P = 0.001). HIV positivity remained associated with GBV-C viremia in multivariate analysis after adjustment for age (OR = 2.23, 95% CI = 1.39-3.58, P = 0.001). GBV-C seropositivity was similar among PWID and healthy volunteers (2.3% vs. 1.7%, respectively; OR = 1.4, 95% CI =0.3-13.5, P = 1). In an Eastern European country we demonstrated that GBV-C viremia is common among PWID, but uncommon among healthy volunteers, and GBV-C seropositivity is infrequent among both groups. Similarly to other European countries and USA, GBV-C 2a is the most common genotype in Estonia. J. Med. Virol. 89:632-638, 2017. © 2016 Wiley Periodicals, Inc.

A comparative hospital-based observational study of mono- and co-infections of malaria, dengue virus and scrub typhus causing acute undifferentiated fever

Positive serology for dengue and/or scrub typhus infection with/without positive malarial smear (designated as mixed or co-infection) is being increasingly observed during epidemics of acute undifferentiated febrile illnesses (AUFIs). We planned to study the clinical and biochemical spectrum of co-infections with Plasmodium sp., dengue virus and scrub typhus and compare these with mono-infection by the same organisms. During the period from December 2012 to December 2013, all cases presenting with AUFIs to a single medical unit of a referral centre in Garhwal region of the north Indian state of Uttarakhand were retrospectively selected and categorised aetiologically as co-infections, malaria, dengue or scrub typhus. The groups thus created were compared in terms of demographic, clinical, biochemical and outcome parameters. The co-infection group (n = 49) was associated with milder clinical manifestations, fewer, milder and non-progressive organ dysfunction, and lesser need for intensive care, mechanical ventilation and dialysis as compared to mono-infections. When co-infections were sub-grouped and compared with the relevant mono-infections, there were differences in certain haematological and biochemical parameters; however, this difference did not translate into differential outcomes. Scrub typhus mono-infection was associated with severe disease in terms of both morbidity and mortality. Malaria, dengue and scrub typhus should be routinely tested in all patients with AUFIs. Co-infections, whether true or due to serological cross-reactivity, appear to be a separate entity so far as presentation and morbidity is concerned. Further insight is needed into the mechanism and identification of the protective infection.

A sequential classification rule based on multiple quantitative tests in the absence of a gold standard

In many medical applications, combining information from multiple biomarkers could yield a better diagnosis than any single one on its own. When there is a lack of a gold standard, an algorithm of classifying subjects into the case and non-case status is necessary for combining multiple markers. The aim of this paper is to develop a method to construct a composite test from multiple applicable tests and derive an optimal classification rule under the absence of a gold standard. Rather than combining the tests, we treat the tests as a sequence. This sequential composite test is based on a mixture of two multivariate normal latent models for the distribution of the test results in case and non-case groups, and the optimal classification rule is derived returning the greatest sensitivity at a given specificity. This method is applied to a real-data example and simulation studies have been carried out to assess the statistical properties and predictive accuracy of the proposed composite test. This method is also attainable to implement nonparametrically.

Interferon-inducible protein 10 (IP-10) is associated with viremia of early HIV-1 infection in Korean patients

Cytokines/chemokines play key roles in modulating disease progression in human immunodeficiency virus (HIV) infection. Although it is known that early HIV-1 infection is associated with increased production of proinflammatory cytokines, the relationship between cytokine levels and HIV-1 pathogenesis is not clear. The concentrations of 18 cytokines/chemokines in 30 HIV-1 negative and 208 HIV-1 positive plasma samples from Korean patients were measured by the Luminex system. Early HIV-1 infection was classified according to the Fiebig stage (FS) based on the characteristics of the patients infected with HIV-1. Concentrations of interleukin-12 (IL-12), interferon-inducible protein-10 (IP-10), macrophage inflammatory protein-1α (MIP-1α) and regulated upon activation, normal T cells expressed and secreted (RANTES) were increased significantly during the early stage of HIV-1 infection (FS II-IV) compared with the HIV-1-negative group. Of these cytokines, an elevated level of IP-10 was the only factor to be correlated positively with a higher viral load during the early stages of HIV-1 infection (FS II-IV) in Koreans (R = 0.52, P < 0.0005). Therefore, these results suggest that IP-10 may be an indicator for HIV-1 viremia and associated closely with viral replication in patients with early HIV-1 infection.

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.

GB virus C coinfections in west African Ebola patients

In 49 patients with known Ebola virus disease outcomes during the ongoing outbreak in Sierra Leone, 13 were coinfected with the immunomodulatory pegivirus GB virus C (GBV-C). Fifty-three percent of these GBV-C(+) patients survived; in contrast, only 22% of GBV-C(-) patients survived. Both survival and GBV-C status were associated with age, with older patients having lower survival rates and intermediate-age patients (21 to 45 years) having the highest rate of GBV-C infection. Understanding the separate and combined effects of GBV-C and age on Ebola virus survival may lead to new treatment and prevention strategies, perhaps through age-related pathways of immune activation.

Virus against virus (VIVI): a potential solution against HIV/AIDS

Most therapeutic regimens are aimed at the use of pharmacologic agents or the induction of immunological response against the pathological agent. However, these methods tend to be insufficient for the management of some of the most debilitating infectious diseases. Here we present a novel therapeutic approach. It involves voluntary super-infection of a subject having HIV/AIDS with a virus (GBV-C), which to date has not been shown to be responsible for any pathology. It has been shown to counter, suppress or eradicate the agent responsible for the severe disease. Several studies demonstrate the role of different micro-organisms in influencing the growth of other pathogens in the human body. This hypothesis requires meticulous testing before its implementation on humans. If the trials are successful, the implications for this hypothesis are promising considering the compliance issues and adverse effects associated with current standard of HIV care.

Human pegivirus RNA is found in multiple blood mononuclear cells in vivo and serum-derived viral RNA-containing particles are infectious in vitro

Human pegivirus (HPgV; previously called GB virus C/hepatitis G virus) has limited pathogenicity, despite causing persistent infection, and is associated with prolonged survival in human immunodeficiency virus-infected individuals. Although HPgV RNA is found in and produced by T- and B-lymphocytes, the primary permissive cell type(s) are unknown. We quantified HPgV RNA in highly purified CD4(+) and CD8(+) T-cells, including naïve, central memory and effector memory populations, and in B-cells (CD19(+)), NK cells (CD56(+)) and monocytes (CD14(+)) using real-time reverse transcription-PCR. Single-genome sequencing was performed on viruses within individual cell types to estimate genetic diversity among cell populations. HPgV RNA was present in CD4(+) and CD8(+) T-lymphocytes (nine of nine subjects), B-lymphocytes (seven of ten subjects), NK cells and monocytes (both four of five). HPgV RNA levels were higher in naïve (CD45RA(+)) CD4(+) cells than in central memory and effector memory cells (P<0.01). HPgV sequences were highly conserved among subjects (0.117±0.02 substitutions per site; range 0.58-0.14) and within subjects (0.006±0.003 substitutions per site; range 0.006-0.010). The non-synonymous/synonymous substitution ratio was 0.07, suggesting a low selective pressure. Carboxyfluorescein succinimidyl ester (CFSE)-labelled HPgV RNA-containing particles precipitated by a commercial exosome isolation reagent delivered CSFE to uninfected monocytes, NK cells and T- and B-lymphocytes, and HPgV RNA was transferred to PBMCs with evidence of subsequent virus replication. Thus, HPgV RNA-containing serum particles including microvesicles may contribute to delivery of HPgV to PBMCs in vivo, explaining the apparent broad tropism of this persistent human RNA virus.

GBV-C viremia and clinical events in advanced HIV infection

GB Virus C (GBV-C) is a non-pathogenic flavivirus, commonly found in HIV infected patients. Studies suggest a survival benefit of GBV-C viremia in HIV infection. Impact of GBV-C viremia was evaluated on clinical outcome in multidrug-resistant HIV. The OPTIMA study enrolled advanced multidrug-resistant HIV patients with a CD4 count ≤300 cells/mm(3). This study included a subset of OPTIMA patients. Primary endpoints included AIDS events or death. GBV-C status was assessed at baseline and last time point on study by real-time PCR. Cox proportional hazards models were used to determine if CD4 count (</>100/mm(3)), treatment assignment, presence or disappearance of GBV-C viremia, GBV-C viral load level and Hepatitis C virus antibody status were associated with outcome. Of 288 patients (98% male, baseline mean age 48 years, HIV viral load 4.67 log10/ml, and CD4 127 cells/mm(3)), 62 (21.5%) had detectable GBV-C viremia. The mortality rate for GBV-C infected subjects was lower, 19/62 (30.7%) versus 87/226 (38.5%), and time to death shorter (HR 0.67, 95% CI 0.41-1.11), but the results were not significantly different. The time to development of AIDS events was not different (HR 0.90, 95% CI 0.52-1.53). Among covariates, only CD4 count (HR 0.28, CI 0.19-0.42) had a significant survival effect. A trend in decreased mortality was seen in GBV-C+ patients with CD4 <100/mm(3) in multivariate analyses. GBV-C co-infection in multidrug-resistant HIV infected patients was associated with a trend in improved survival but not decreased AIDS events. Analysis was limited by cohort size.

The National Heart, Lung, and Blood Institute Recipient Epidemiology and Donor Evaluation Study (REDS-III): a research program striving to improve blood donor and transfusion recipient outcomes

BACKGROUND

The Recipient Epidemiology and Donor Evaluation Study-III (REDS-III) is a 7-year multicenter transfusion safety research initiative launched in 2011 by the National Heart, Lung, and Blood Institute.

STUDY DESIGN AND METHODS

The domestic component involves four blood centers, 12 hospitals, a data coordinating center, and a central laboratory. The international component consists of distinct programs in Brazil, China, and South Africa, which involve US and in-country investigators.

RESULTS

REDS-III is using two major methods to address key research priorities in blood banking and transfusion medicine. First, there will be numerous analyses of large "core" databases; the international programs have each constructed a donor and donation database while the domestic program has established a detailed research database that links data from blood donors and their donations, the components made from these donations, and data extracts from the electronic medical records of the recipients of these components. Second, there are more than 25 focused research protocols involving transfusion recipients, blood donors, or both that either are in progress or are scheduled to begin within the next 3 years. Areas of study include transfusion epidemiology and blood utilization, transfusion outcomes, noninfectious transfusion risks, human immunodeficiency virus-related safety issues (particularly in the international programs), emerging infectious agents, blood component quality, donor health and safety, and other donor issues.

CONCLUSIONS

It is intended that REDS-III serve as an impetus for more widespread recipient and linked donor-recipient research in the United States as well as to help assure a safe and available blood supply in the United States and in international locations.

Inhibition of HIV type 1 replication by human T lymphotropic virus types 1 and 2 Tax proteins in vitro

Patients with HIV-1 and human T-lymphotropic virus type 2 (HTLV-2) coinfections often exhibit a clinical course similar to that seen in HIV-1-infected individuals who are long-term nonprogressors. These findings have been attributed in part to the ability of HTLV-2 to activate production of antiviral chemokines and to downregulate the CCR5 coreceptor on lymphocytes. To further investigate these observations, we tested the ability of recombinant Tax1 and Tax2 proteins to suppress HIV-1 viral replication in vitro. R5-tropic HIV-1 (NLAD8)-infected peripheral blood mononuclear cells (PBMCs) were treated daily with recombinant Tax1 and Tax2 proteins (dosage range 1-100 pM). Culture supernatants were collected at intervals from days 1 to 22 postinfection and assayed for levels of HIV-1 p24 antigen by ELISA. Treatment of PBMCs with Tax2 protein resulted in a significant reduction in HIV-1 p24 antigen levels (p<0.05) at days 10, 14, and 18 postinfection compared to HIV-1-infected or mock-treated PBMCs. This was preceded by the detection of increased levels of CC-chemokines MIP-1α/CCL3, MIP-1β/CCL4, and RANTES/CCL5 on days 1-7 of infection. Similar, but less robust inhibition was observed in Tax1-treated PBMCs. These results support the contention that Tax1 and Tax2 play a role in generating antiviral responses against HIV-1 in vivo and in vitro.

Interleukin-2 inhibits HIV-1 replication in some human T cell lymphotrophic virus-1-infected cell lines via the induction and incorporation of APOBEC3G into the virion

IL-2 has been used in culture of primary T cells to maintain cell proliferation. We have previously reported that IL-27 inhibits HIV-1 replication in primary T cells in the presence of IL-2. To gain a better understanding of the mechanisms involved in this inhibitory effect, we attempted to investigate in detail the effects of IL-27 and IL-2 using several cell lines. Unexpectedly, IL-27 did not inhibit HIV-1 in T cell lines, whereas IL-2 inhibited HIV-1 replication in the human T cell lymphotrophic virus (HTLV)-1-transformed T cell lines, MT-2, MT-4, SLB-1, and ATL-2. No effects were seen in HTLV-1-negative cell lines. Utilizing MT-2 cells, we demonstrated that IL-2 treatment inhibited HIV-1 syncytia-inducing ability and dose-dependently decreased supernatant p24 antigen levels by >90%. Using real time PCR and Western blot analysis, we observed that IL-2 treatment induced the host restriction factor, APOBEC3G with accumulation into the lower molecular mass active form as characterized by FPLC. Further analysis revealed that the virus recovered from IL-2-treated MT-2 cells had impaired replication competency. This was found to be due to incorporation of APOBEC3G into the virion despite the presence of Vif. These findings demonstrate a novel role for IL-2 in regulating production of infectious HIV-1 virions in HTLV-1-infected cells through the induction of APOBEC3G.

Cell-Mediated Immunity in Elite Controllers Naturally Controlling HIV Viral Load

The natural course of human immunodeficiency virus (HIV) infection is characterized by high viral load, depletion of immune cells, and immunodeficiency, ultimately leading to acquired immunodeficiency syndrome phase and the occurrence of opportunistic infections and diseases. Since the discovery of HIV in the early 1980s a naturally selected population of infected individuals has been emerged in the last years, characterized by being infected for many years, with viremia constantly below detectable level and poor depletion of immune cells. These individuals are classified as “elite controllers (EC) or suppressors” and do not develop disease in the absence of anti-retroviral therapy. Unveiling host factors and immune responses responsible for the elite status will likely provide clues for the design of therapeutic vaccines and functional cures. Scope of this review was to examine and discuss differences of the cell-mediated immune responses between HIV+ individuals with disease progression and EC.

GB virus type C E2 protein inhibits human immunodeficiency virus type 1 assembly through interference with HIV-1 gag plasma membrane targeting

GB virus type C (GBV-C) is a single-stranded positive-sense RNA virus classified in the Flaviviridae family. Persistent coinfection with GBV-C is associated with lower human immunodeficiency virus type 1 (HIV-1) load, higher CD4(+) T-cell count, and prolonged survival in HIV-1 coinfected patients. The GBV-C envelope glycoprotein E2 has been reported to interfere with HIV-1 entry. In this study, we showed that the expression of GBV-C E2 inhibited HIV-1 Gag assembly and release. Expression of glycosylated GBV-C E2 inhibited HIV-1 Gag precursor processing, resulting in lower production of CAp24 and MAp17, while the overall expression level of the Gag precursor Pr55 remained unchanged. Membrane floatation gradient and indirect immunofluorescence confocal microscopy analysis showed that glycosylated E2 disrupted HIV-1 Gag trafficking to the plasma membrane, resulting in Gag accumulation in subcellular compartments. This interference in HIV-1 Gag trafficking led to diminished HIV-1 particle production, which is a critical step for HIV-1 to infect new host cells. These findings shed light on a novel mechanism used by GBV-C E2 to inhibit HIV-1 replication and may provide insight into new approaches for suppressing HIV-1 replication.

HIV-1 fusion is blocked through binding of GB Virus C E2-derived peptides to the HIV-1 gp41 disulfide loop [corrected]

A strategy for antiviral drug discovery is the elucidation and imitation of viral interference mechanisms. HIV-1 patients benefit from a coinfection with GB Virus C (GBV-C), since HIV-positive individuals with long-term GBV-C viraemia show better survival rates than HIV-1 patients without persisting GBV-C. A direct influence of GBV-C on HIV-1 replication has been shown in coinfection experiments. GBV-C is a human non-pathogenic member of the flaviviridae family that can replicate in T and B cells. Therefore, GBV-C shares partly the same ecological niche with HIV-1. In earlier work we have demonstrated that recombinant glycoprotein E2 of GBV-C and peptides derived from the E2 N-terminus interfere with HIV entry. In this study we investigated the underlying mechanism. Performing a virus-cell fusion assay and temperature-arrested HIV-infection kinetics, we provide evidence that the HIV-inhibitory E2 peptides interfere with late HIV-1 entry steps after the engagement of gp120 with CD4 receptor and coreceptor. Binding and competition experiments revealed that the N-terminal E2 peptides bind to the disulfide loop region of HIV-1 transmembrane protein gp41. In conjunction with computational analyses, we identified sequence similarities between the N-termini of GBV-C E2 and the HIV-1 glycoprotein gp120. This similarity appears to enable the GBV-C E2 N-terminus to interact with the HIV-1 gp41 disulfide loop, a crucial domain involved in the gp120-gp41 interface. Furthermore, the results of the present study provide initial proof of concept that peptides targeted to the gp41 disulfide loop are able to inhibit HIV fusion and should inspire the development of this new class of HIV-1 entry inhibitors.

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.

GB virus C infection is associated with altered lymphocyte subset distribution and reduced T cell activation and proliferation in HIV-infected individuals

GBV-C infection is associated with prolonged survival and with reduced T cell activation in HIV-infected subjects not receiving combination antiretroviral therapy (cART). The relationship between GBV-C and T cell activation in HIV-infected subjects was examined. HIV-infected subjects on cART with non-detectable HIV viral load (VL) or cART naïve subjects were studied. GBV-C VL and HIV VL were determined. Cell surface markers of activation (CD38(+)/HLA-DR(+)), proliferation (Ki-67+), and HIV entry co-receptor expression (CCR5+ and CXCR4+) on total CD4+ and CD8+ T cells, and on naïve, central memory (CM), effector memory (EM), and effector CD4+ and CD8+ subpopulations were measured by flow cytometry. In subjects with suppressed HIV VL, GBV-C was consistently associated with reduced activation in naïve, CM, EM, and effector CD4+ cells. GBV-C was associated with reduced CD4+ and CD8+ T cell surface expression of activation and proliferation markers, independent of HIV VL classification. GBV-C was also associated with higher proportions of naïve CD4+ and CD8+ T cells, and with lower proportions of EM CD4+ and CD8+ T cells. In conclusion, GBV-C infection was associated with reduced activation of CD4+ and CD8+ T cells in both HIV viremic and HIV RNA suppressed patients. Those with GBV-C infection demonstrated an increased proportion of naive T cells and a reduction in T cell activation and proliferation independent of HIV VL classification, including those with suppressed HIV VL on cART. Since HIV pathogenesis is thought to be accelerated by T cell activation, these results may contribute to prolonged survival among HIV infected individuals co-infected with GBV-C. Furthermore, since cART therapy does not reduce T cell activation to levels seen in HIV-uninfected people, GBV-C infection may be beneficial for HIV-related diseases in those effectively treated with anti-HIV therapy.

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 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.

Recombinant interferon-γ lentivirus co-infection inhibits adenovirus replication ex vivo

Recombinant interferon-γ (IFNγ) production in cultured lentivirus (LV) was explored for inhibition of target virus in cells co-infected with adenovirus type 5 (Ad5). The ability of three different promoters of CMV, EF1α and Ubiquitin initiating the enhanced green fluorescence protein (GFP) activities within lentiviruses was systematically assessed in various cell lines, which showed that certain cell lines selected the most favorable promoter driving a high level of transgenic expression. Recombinant IFNγ lentivirus carrying CMV promoter (LV-CMV-IFNγ) was generated to co-infect 293A cells with a viral surrogate of recombinant GFP Ad5 in parallel with LV-CMV-GFP control. The best morphologic conditions were observed from the two lentiviruses co-infected cells, while single adenovirus infected cells underwent clear pathologic changes. Viral load of adenoviruses from LV-CMV-IFNγ or LV-CMV-GFP co-infected cell cultures was significantly lower than that from adenovirus alone infected cells (P=0.005-0.041), and the reduction of adenoviral load in the co-infected cells was 86% and 61%, respectively. Ad5 viral load from LV-CMV-IFNγ co-infected cells was significantly lower than that from LV-CMV-GFP co-infection (P=0.032), which suggested that IFNγ rather than GFP could further enhance the inhibition of Ad5 replication in the recombinant lentivirus co-infected cells. The results suggest that LV-CMV-IFNγ co-infection could significantly inhibit the target virus replication and might be a potential approach for alternative therapy of severe viral diseases.

Acquisition of GB virus type C and lower mortality in patients with advanced HIV disease

BACKGROUND

GB virus type C (GBV-C) is transmitted by sexual or parenteral exposure and is prevalent among patients receiving blood products. GBV-C is associated with lower human immunodeficiency virus (HIV) RNA and better survival among HIV-infected patients. Open questions are the presence and the direction of any causal relationship between GBV-C infection and HIV disease markers in the context of highly active antiretroviral therapy (HAART).

METHODS

We used a limited access database obtained from the National Heart, Lung, and Blood Institute's Viral Activation Transfusion Study (VATS), a randomized controlled trial of leukoreduced vs nonleukoreduced transfusions to HIV-infected transfusion-naive patients. Blood samples from 489 subjects were tested for GBV-C markers. Cox regression models and inverse probability of treatment weights were used to examine the association between GBV-C coinfection and mortality in the VATS cohort.

RESULTS

We found a significant reduction in mortality among GBV-C coinfected VATS subjects, after adjusting for HAART status, HIV RNA level, and CD4 cell count at baseline. Acquisition of GBV-C RNA (n = 39) was associated with lower mortality in 294 subjects who were GBV-C negative at baseline, adjusting for baseline covariates (hazard ratio = 0.22, 95% confidence interval [CI]: .08-.58) and in models in which weights were used to control for time-updated covariates (odds ratio = 0.21, 95% CI: .08-.60).

CONCLUSIONS

GBV-C viremia is associated with lower mortality, and GBV-C acquisition via transfusion is associated with a significant reduction in mortality in HIV-infected individuals, controlling for HIV disease markers. These findings provide the first evidence that incident GBV-C infection alters mortality in HIV-infected patients.

Influence of GB virus C on IFN-γ and IL-2 production and CD38 expression in T lymphocytes from chronically HIV-infected and HIV-HCV-co-infected patients

This study was designed to assess the effect of GB virus (GBV)-C on the immune response to human immunodeficiency virus (HIV) in chronically HIV-infected and HIV- hepatitis C virus (HCV)-co-infected patients undergoing antiretroviral therapy. A cohort of 159 HIV-seropositive patients, of whom 52 were HCV-co-infected, was included. Epidemiological data were collected and virological and immunological markers, including the production of interferon gamma (IFN-γ) and interleukin (IL)-2 by CD4, CD8 and Tγδ cells and the expression of the activation marker, CD38, were assessed. A total of 65 patients (40.8%) presented markers of GBV-C infection. The presence of GBV-C did not influence HIV and HCV replication or TCD4 and TCD8 cell counts. Immune responses, defined by IFN-γ and IL-2 production and CD38 expression did not differ among the groups. Our results suggest that neither GBV-C viremia nor the presence of E2 antibodies influence HIV and HCV viral replication or CD4 T cell counts in chronically infected patients. Furthermore, GBV-C did not influence cytokine production or CD38-driven immune activation among these patients. Although our results do not exclude a protective effect of GBV-C in early HIV disease, they demonstrate that this effect may not be present in chronically infected patients, who represent the majority of patients in outpatient clinics.

Characterization of a peptide domain within the GB virus C envelope glycoprotein (E2) that inhibits HIV replication

GB virus C (GBV-C) infection is associated with prolonged survival in HIV-infected cohorts, and GBV-C E2 protein inhibits HIV entry when added to CD4+ T cells. To further characterize E2 effects on HIV replication, stably transfected Jurkat cell lines expressing GBV-C E2 or control sequences were infected with HIV and replication was measured. HIV replication (all 6 isolates studied) was inhibited in all cell lines expressing a region of 17 amino acids of GBV-C E2, but not in cell lines expressing E2 without this region. In contrast, mumps and yellow fever virus replication was not inhibited by E2 protein expression. Synthetic GBV-C E2 17mer peptides did not inhibit HIV replication unless they were fused to a tat-protein-transduction-domain (TAT) for cellular uptake. These data identify the region of GBV-C E2 protein involved in HIV inhibition, and suggest that this GBV-C E2 peptide must gain entry into the cell to inhibit HIV.

GB virus type C infection polarizes T-cell cytokine gene expression toward a Th1 cytokine profile via NS5A protein expression

Human immunodeficiency virus (HIV) disease progression is associated with a helper T cell 1 (Th1) to helper T cell 2 (Th2) cytokine profile switch. Persistent GB virus type C (GBV-C) infection is associated with survival and a serum Th1 cytokine profile in HIV-infected individuals. We found that GBV-C infection increased gene expression of Th1 cytokines and decreased Th2 cytokine expression in peripheral blood mononuclear cells. Furthermore, expression of GBV-C NS5A protein in a CD4(+) cell line resulted in upregulation of Th1 cytokines (tumor necrosis factor α) and downregulation of Th2 cytokines (interleukin 4, interleukin 5, interleukin 10, interleukin 13). GBV-C-induced modulation in T-cell cytokines may contribute to the beneficial effect of GBV-C in HIV-infected individuals.