A novel subtype of GB virus C/hepatitis G virus genotype 1 detected uniquely in patients with hemophilia in Japan

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.

Detection and phylogenetic analysis of human pegivirus (GBV-C) among blood donors and patients infected with hepatitis B virus (HBV) in Qatar

Human Pegivirus (HPgV), formerly GB virus-C/Hepatitis G virus (GBV-C/HGV), collectively known as GBV-C, is widely spread and has been reported to be associated with non-A-E hepatitis. To our knowledge, no previous study was conducted about HPgV in Qatar. Thus, the objectives of this study were as follows: (i) to determine the rates of HPgV infection in Qatar among healthy blood donors and HBV-infected patients, and (ii) to determine the most predominant HPgV genotype in Qatar. A total of 714 blood plasma samples from healthy donors (612) and HBV-infected patients (102) were collected. RNA was extracted, reversed transcribed, and then subjected for HPgV detection by two round-nested PCR using primers amplifying a 208 bp of 5'-UTR of the HPgV. For genotyping, the 5'-UTR PCR products (from 25 randomly picked samples) were cloned and sequenced. The overall infection rate of HPgV in Qatar was 13.3%. There was no significant difference (P = 0.41) in the infection rates between healthy donor (13.7%) and in HBV-infected patients (10.7%). Moreover, we did not find any significant association between HPgV infection rates and nationality, sex, or age (P > 0.05). Sequence analysis of 40 5'-UTR PCR amplicons yielded the European genotype 2 as most predominant in Qatar, although other genotypes (5 and 7) were also present. Our results indicate that there is no strong correlation between HPgV infection rate, condition, nationality, age, and sex, and genotype 2 is most predominant in Qatar.

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 (GBV-C) evolutionary patterns revealed by analyses of reference genomes, E2 and NS5B sequences amplified from viral strains circulating in the Lisbon area (Portugal)

GBV-C is a non-pathogenic virus that is largely dispersed in different human populations. The phylogenetic analysis of the 5'-untranslated region (5'UTR) of the GBV-C genome has led to the segregation of viral strains into six genotypes, but incongruent results are frequently obtained depending on the genome region analyzed. In this report, different phylogenetic approaches and multivariate statistics were combined to disclose evolutionary patterns that contribute to shape GBV-C evolution. The data here presented indicate: (i) that the phylogenetic noise was mostly determined by the size of the analyzed sequence, rather than by its position on the viral genome; (ii) that most genomic segments in the coding sequence seemed to evolve under a similar evolution model, which was different from that which best fits the 5'UTR, with overall large heterogeneity of rate change across the sequence; (iii) that due to saturation of transversions occurring in the 5'UTR at genetic distances <0.10, care should be taken in drawing conclusions about the tree topologies involving the deeper branches, especially when using distance-based methods; (iv) that a non-uniform distribution of InSi and dS occurs over the viral ORF highlighting regions of the viral genome with remarkably low levels of silent substitutions, and implying that the observed differences may contribute to the detected phylogenetic incongruences; and finally (v) that genetic recombination clearly impacts the GBV-C evolution extensively, this being shown for both reference genomes and NS5B GBV-C sequences amplified from Portuguese residents.

A novel genotype of GB virus C: its identification and predominance among injecting drug users in Yunnan, China

GB virus C (GBV-C) is prevalent globally and particularly among individuals at risk of parental exposures. Based on genetic diversity, this virus is now classified into six genotypes and many subtypes with distinct geographical distribution. In this study, 120 Injecting Drug Users (IDUs) were recruited from Yunnan province, China. Among them, 43 (35.8%) were positive for GBV-C RNA, 70 (58.3%) and 103 (85.8%) sero-positive for HIV-1 and HCV respectively. This revealed 18.3% of IDUs having GBV-C/HIV/HCV triple infection, which is significantly higher than 7.5% of GBV-C/HIV-1 and 10% of GBV-C/HCV dual infection rates (P<0.05). Based on 5′UTR sequences, the identified 43 viral isolates can be classified into three phylogenetic groups: one (2.3%) and two (4.7%) belonged to genotype 3 and 4, respectively, and the remaining 40 (93%) formed a new group with 97% of bootstrap support. This new GBV-C group was further confirmed by characterizing the E2 region and full-length genome sequences. Analysis of 187 nt 5′UTR sequence showed three previous reported isolates from Southeast Asia were re-classified into this new group. It implies they have the same origin with strains from Yunnan. Although we provisionally assigned this new group as GBV-C genotype 7, a simpler five groups of GBV-C nomenclature is recommended. Genotype 4, 6 and the newly designated genotype 7 could be reclassified as one group, which may represent a single GBV-C genotype. The classification of the other four groups was corresponding to that of previous reported genotype 1, 2, 3 and 5. Furthermore, the diversity of amino acid sequence in the E2 region was analyzed. The inhibitory effect of GBV-C genotype 7 on HIV-1 cell entry could be deduced. Since GBV-C may have a beneficial effect on AIDS disease progression and interact with HCV during co-infection, this finding may raise interests in future studies on this virus that was previously thought to be a “non-pathogenic virus”.

Beneficial effect of GB virus C co-infection in Human Immunodeficiency Virus type 1-infected individuals

Several reports have documented a better prognosis for HIV-1-infected patients co-infected with GBV-C, while other reports have contradicted such findings with the result that this issue remains controversial. We attempted to clarify the complicated status of the effect of GBV-C co-infection on HIV-1-infected patients. GBV-C RNA was detected in 37 samples in 182 HIV-1-infected patients (20.3%) using RT/nested PCR. Of these, 3 were determined to be GBV-C genotype 1, 12 were genotype 2, and the remaining 22 were genotype 3. The GBV-C viral load quantified by real-time PCR ranged from 7.8x10(3) to 3.3x10(6) copies/ml. Weakly negative correlation was observed between GBV-C viral load and HIV-1 viral load in 19 HAART-naïve patients, indicating that a higher GBV-C viral load is associated with a greater suppression of HIV-1 replication. A previously published in vitro study suggested that GBV-C infection would induce up-regulation of RANTES, leading to suppression of HIV-1 replication. However, in our present study, the blood RANTES level was significantly lower in the GBV-C co-infected group than in the uninfected group (190-9,959 vs. 264-31,038 pg/ml, P=0.004). Our results suggested that a suppression of HIV-1 replication by GBV-C co-infection is not mediated by up-regulated RANTES, and thus call for another as yet unknown factor.

GB virus C: insights into co-infection

GB virus C (GBV-C) is a single stranded positive sense RNA virus, which is a member of the Flaviviridae. It has a close sequence homology and genomic organisation to hepatitis C virus (HCV). However, unlike HCV it is not hepatotrophic. GBV-C replicates within cells of the haemopoietic lineage, in particular lymphocytes. No disease has been associated with GBV-C infection but co-infection with human immunodeficiency virus (HIV) leads to improved morbidity and mortality for the HIV infected individual and slows progression to acquired immunodeficiency syndrome. This potential benefit of GBV-C has been demonstrated in the pre and post highly active anti-retroviral treatment (HAART) eras. GBV-C has been found to decrease HIV replication in in vitro models. The mechanism of the beneficial effect of GBV-C appears to be mediated by alterations in the cellular immune response, the details of which remain unclear. Despite this, there continues to be controversy regarding the influence of GBV-C on HIV as several reports have questioned the beneficial effect. GBV-C does not appear to influence liver related disease in subjects co-infected with HCV or hepatitis B virus (HBV). Combination of HIV and HCV leads to accelerated liver disease. The influence of GBV-C in this situation is yet to be determined. Elucidation of the putative protective effect of GBV-C in HIV co-infection could potentially identify novel targets for anti-HIV therapeutics and lead to the development of disease modifying vaccines.

Detection and genotyping of GBV-C virus in the United Arab Emirates

GB virus-C/Hepatitis G virus (GBV-C/HGV), collectively known as GBV-C, is spread widely and has been reported to be associated with non A-E hepatitis. The aim of the current project was to determine the rate of infection and genotypic characteristics of GBV-C in the United Arab Emirates (UAE). A total of 379 plasma/serum samples representing different populations in the UAE and comprising healthy as well as patients positive for HBV and HCV were screened using RT-PCR/nested PCR of the 5'-untranslated region (UTR). National subjects (n=168) and non-nationals residing in the UAE (n=211) were tested. The results obtained showed that the rate of GBV-C infection in healthy nationals, and those positive for HCV or HBV were 11.1%, 14.3%, and 5.7%, respectively, compared to 8.3%, 33.3%, and 8.6%, respectively, in non-nationals. No statistically significant correlation between infection with GBV-C and HCV or HBV (P>0.05) was found. Sequence analysis of the 5'-UTR using 37 and 46 clones from 8 and 6 healthy nationals and non-nationals, respectively, revealed the prevalence of the European/North American genotype 2 when compared to the five reference genotypes in GenBank.