Prevalence of hepatitis G virus infection among patients with liver diseases in Japan

Although a new RNA virus, designated hepatitis G virus (HGV) has recently been identified, the clinical significance of HGV infection is still unclear. To approach this problem, we studied the prevalence of HGV infection on patients with liver diseases in Japan by nested reverse transcription polymerase chain reaction using primers deduced from 5′-noncoding region. The positive rate of HGV RNA was 6.8% in all tested liver disease patients (45 of 663), while 1.4% ($\text{2}\text{145}$) in healthy individuals. Among these patients, HGV RNA was detected in 6.9% ($\text{4}\text{58}$) of acute hepatitis, 7% ($\text{16}\text{229}$) of chronic hepatitis, 8.6% ($\text{5}\text{58}$) of liver cirrhosis and 12.2% ($\text{17}\text{139}$) of hepatocellular carcinoma (HCC), but few or none in non-viral liver diseases. HGV coinfection with hepatitis B virus and hepatitis C virus (HCV) were present in 8.9 and 66.7% of these patients, respectively, while 22.2% of patients were positive for HGV alone. In 54 patients with acute hepatitis that is seronegative for hepatitis A-E, four of them (7.4%) were positive for HGV. Liver histology from a HCC patient infected with HGV alone revealed that lymphocytic infiltration of portal trcts in (69%) had not received blood transfusion. Nucleotide sequence analyses in four patients confirmed that these PCR products were derived from HGV genome sequences and 90% identical to those of HGV prototype from American patients, and 97% identical among Japanese isolates. These results indicate that generally 6.8% of Japanese patients with liver diseases had HGV infection and most of them was coinfected with HCV. This suggest that HGV might be related to liver diseases. The routes of transmission of HGV require clarification.