Blood-bank screening for hepatitis G

Whole-genome sequencing of human Pegivirus variant from an Egyptian patient co-infected with hepatitis C virus: a case report

Background

Human pegivirus (HPgV) is structurally similar to hepatitis C virus (HCV) and was discovered 20 years ago. Its distribution, natural history and exact rule of this viral group in human hosts remain unclear. Our aim was to determine, by deep next-generation sequencing (NGS), the entire genome sequence of HPgV that was discovered in an Egyptian patient while analyzing HCV sequence from the same patient. We also inspected whether the co-infection of HCV and HPgV will affect the patient response to HCV viral treatment. To the best of our knowledge, this is the first report for a newly isolated HPgV in an Egyptian patient who is co-infected with HCV.

Case presentation

The deep Next Generation Sequencing (NGS) technique was used to detect HCV sequence in hepatitis C patient’s plasma. The results revealed the presence of HPgV with HCV. This co-infection was confirmed using conventional PCR of the HPgV 5′ untranslated region. The patient was then subjected to direct-acting-antiviral treatment (DAA). At the end of the treatment, the patient showed a good response to the HCV treatment (i.e., no HCV-RNA was detected in the plasma), while the HPgV-RNA was still detected. Sequence alignment and phylogenetic analyses demonstrated that the detected HPgV was a novel isolate and was not previously published.

Conclusion

We report a new variant of HPgV in a patient suffering from hepatitis C viral infection.

Hepatitis G virus

A number of new hepatitis viruses (G, TT, SEN) were discovered late in the past century. We review the data available in the literature and our own findings suggesting that the new hepatitis G virus (HGV), disclosed in the late 1990s, has been rather well studied. Analysis of many studies dealing with HGV mainly suggests the lymphotropicity of this virus. HGV or GBV-C has been ascertained to influence course and prognosis in the HIV-infected patient. Until now, the frequent presence of GBV-C in coinfections, hematological diseases, and biliary pathology gives no grounds to determine it as an “accidental tourist” that is of no significance. The similarity in properties of GBV-C and hepatitis C virus (HCV) offers the possibility of using HGV, and its induced experimental infection, as a model to study hepatitis C and to develop a hepatitis C vaccine.

GB virus-C/hepatitis G virus infection in Taiwan: a virus that fails to cause a disease?

Recently, an RNA virus designated GB virus-C or hepatitis G virus (GBV-C/HGV) was identified; however, its clinical significance remains uncertain. This discovery prompted us to investigate the virological, epidemiological and clinical implications of GBV-C/HGV infection in Taiwan where chronic liver diseases and liver cancer are endemic. Our results showed that genetic heterogeneity of GBV-C/HGV isolates exists, and primers from the highly conserved 5' untranslated region of viral genome can efficiently detect GBV-C/HGV RNA. Epidemiological surveys showed that GBV-C/HGV infection is common in high-risk groups in Taiwan, and its coinfection does not aggravate the course of chronic hepatitis B or C. A prospective study of transfusion-transmitted GBV-C/HGV infection also showed GBV-C/HGV does not cause classic hepatitis in most patients. In addition, GBV-C/HGV plays a minimal role in causing fulminant hepatitis. Like hepatitis C virus, sexual transmission of GBV-C/HGV exists. The risk increases with prolonged duration of exposure. In addition, high-titered maternal viremia and mode of delivery are associated with the mother-to-infant transmission of GBV-C/HGV. Interestingly, we found that GBV-C/HGV exerts no suppression on levels of chronic hepatitis B or hepatitis C viremia, and GBV-C/HGV responds to interferon; however, ribavirin plus interferon does not induce a higher sustained response. As to the replication sites of GBV-C/HGV, our preliminary results showed liver and peripheral blood mononuclear cells are not the major sites for GBV-C/HGV replication, and thus GBV-C/HGV is not a primary hepatotropic virus. In conclusion, transfusion and exchange of body fluids indeed can transmit GBV-C/HGV; however, current lines of evidence suggest that GBV-C/HGV fails to cause a disease.

HGV: the identification, biology and prevalence of an orphan virus

Hepatitis G virus (HGV) and GB virus C (GBV-C) (both hereinafter referred to as HGV) were independently identified in patients with hepatitis of unknown aetiology. HGV is a positive-sense RNA virus of the family Flaviviridae. The virus can establish both acute and chronic infection and appears to be sensitive to interferon. Horizontal transmission is mainly parenteral, although other routes such as vertical have been well documented. High risk groups include intravenous drug users (i.v.DUs), the multiply transfused, haemodialysis patients and haemophiliacs. Up to 90% of i.v.DUs are positive for either HGV-RNA or antibodies to HGV envelope-2 protein (anti-E2). HGV is frequently detected in patients with HBV and HCV infection. Its link to hepatitis has now become less certain. Only around 3-6% of non-A E hepatitis cases are HGV viraemic, clearly showing that HGV is not the major cause of idiopathic hepatitis as originally hoped. Around 1-5% of volunteer blood donors in developed countries are HGV viraemic, but the prevalence is 10-20% in the general population in some developing countries. At present, it is not known whether HGV is associated with other diseases in humans, is a passenger virus, or only becomes virulent under certain conditions.