Impact of hepatitis G virus co-infection on the course of hepatitis C virus infection before and after liver transplantation

BACKGROUND/AIMS: Hepatitis G virus (HGV), a new RNA virus that is parenterally transmitted, has frequently been found in patients with chronic hepatitis C (HCV) infection but its role in chronic liver disease is unknown. The purpose of this study was to determine the prevalence of HGV infection in transplantation patients infected with hepatitis C and to assess the impact of HGV co-infection on the course of HCV infection after liver transplantation. METHODS: Eighty-nine liver transplantation recipients with persistent hepatitis C viremia detected by polymerase chain reaction (PCR) were evaluated. Serum samples were tested before and after liver transplantation for HGV RNA by two different PCR methods: LC assay (Abbott Laboratories) and an RT-PCR procedure which we developed using the silica gel technique for extraction of the HGV RNA. E2 antibodies were detected before orthotopic liver transplantation by an EIA-test. HCV RNA was quantified by branched DNA assay, and HCV genotype was determined. A mean of nine liver biopsy specimens were examined for each patient and the severity of the lesions was compared in HCV-positive patients with or without HGV co-infection. RESULTS: The concordance between the two HGV RNA detection methods was excellent and the reproducibility of our RT-PCR procedure was confirmed. The prevalence of pretransplantation and posttransplantation HGV infection was 11% and 19%, respectively. Pretransplantation HGV infection was positively correlated with posttransplantation HGV infection (p<0.001). Before transplantation the E2 antibodies seroprevalence was 34%. Seven patients became HGV RNA positive after transplantation, but all of them were negative for E2 antibodies. Among the patients who remained RNA negative after liver transplantation, 40% were positive for E2 antibodies (p=0.04). Pretransplantation clinical features (except AST mean value) were not different in patients with HCV and HGV co-infection and those with HCV only. After a mean follow-up of 34 months (range: 6 to 70), 67/89 (75%) patients developed histological features of recurrent hepatitis but the frequency of the occurrence of graft hepatitis was not different between HGV/HCV co-infected patients and those with HCV alone (p=0.89). The mean interval from orthotopic liver transplantation to recurrence was 12.2 months (range: 3-63), which was not different for HVG/HVC-co-infected patients and HCV-infected patients. The histological severity of posttransplantation liver disease, and the graft and patient survival were not different for patients with and without HGV co-infection. CONCLUSIONS: Our results suggest the general persistence of HGV infection after liver transplantation, but HGV co-infection did not appear to influence the posttransplantation course of HCV infection. Before transplantation the prevalence of E2 antibodies was 34%, and our data clearly indicate that E2 antibodies were protective against HGV infection.