Detection of GB virus-C/hepatitis G virus genome in peripheral blood mononuclear cells and liver tissue.

The replication site for the GB virus-C/hepatitis G virus (GBV-C/HGV) was investigated by using polymerase chain reaction (PCR)-based assays and in situ hybridisation. A total of 28 patients with consecutive GBV-C/HGV infection were enrolled in this study: Nine patients were being treated with immunosuppressive therapy after liver transplantation, and the remaining 19 patients were not receiving such treatment. GBV-C/HGV RNA was detected by using reverse transcriptase-polymerase chain reaction (RT-PCR) and was quantitated by using competitive RT-PCR in all patients. Positive and negative strands of GBV-C/HGV RNA in liver tissue were detected with in situ hybridisation by using RNA probes that were specific for the GBV-C/HGV genome. Concentrations of GBV-C/HGV RNA in serum were significantly higher (P=0.003) in the nine patients who were receiving immunosuppression (median, 10(7) copy/ml; range, 10(5)-10(7)) than in the 19 patients who were not receiving immunosuppressive therapy (median, 10(4) copy/ml; range, 10(2)-10(7)). In situ hybridisation of GBV-C/ HGV RNA was performed on paraffin-embedded liver tissue that was obtained from six patients with GBV-C/HGV infection. Two of those six patients were receiving immunosuppressive therapy, and four were not. Significant positive signals were observed in the samples from two of the six patients who were infected with GBV-C/HGV, but such signals were not observed in any of the six patients who were without the infection. The two patients with positive signals (both were undergoing immunosuppressive therapy) showed both positive and negative strands of GBV-C/HGV RNA in mononuclear cells that infiltrated into portal areas, but neither of the strands was observed in hepatocytes. Moreover, the GBV-C/HGV replication was analysed in peripheral blood mononuclear cells by using strand-specific PCR (conventional RT-PCR and rTth method). Two of the six patients were positive for negative-strand GBV-C/HGV RNA by using conventional RT-PCR. In conclusion, GBV-C/HGV replication was active under an immunosuppressive state, and it is suggested that GBV-C/HGV replicates in mononuclear cells.