Is hepatitis G/GB virus-C virus hepatotropic? Detection of hepatitis G/GB virus-C viral RNA in liver and serum.

The recently identified hepatitis G virus (HGV, also named GB virus-C, GBV-C) appears to have similarities to hepatitis C virus and other flaviviridae. To better understand its clinical significance and hepatotropism, we collected liver tissue and matched serum samples from 56 patients undergoing liver transplantation. HGV/GBV-C RNA was detected by reverse transcription-nested PCR, using primers from the relatively conserved 5' noncoding region of the genome to detect HGV/GBV-C RNA and the amount was semiquantitatively estimated by serial 10-fold endpoint dilution. The presence and amount of HCV RNA was estimated by the same methodology. Seventeen patients (30%) had HGV/GBV-C RNA detectable either in liver or in serum, including two of three with cryptogenic liver disease. Interestingly, 5 of 17 (29%) patients had HGV/GBV-C RNA in serum but not liver, even with repeated testing of hepatic RNA from different portions of the liver. Furthermore, the titer of HGV/GBV-C RNA was significantly lower in liver than in serum in most samples (mean log titer, 1.33 vs. 2.56, P < 0.05). In contrast, all 21 patients with HCV RNA in serum also had the virus detectable in liver. In five patients coinfected with HCV and HGV/GBV-C, the mean titer of HCV RNA in liver was higher than that in serum (log titer, 2.8 vs. 3.0, P > 0.05). Thus, our results suggest that HGV/GBV-C is probably not hepatotropic and may replicate predominantly in sites other than the liver. These findings brings into question the role of HGV in causing significant liver disease.