Genotyping system of GBV-C/HGV type 1 to type 4 by the polymerase chain reaction using type-specific primers and geographical distribution of viral genotypes.

Based on variation in nucleotide sequence of 5'-untranslated region, GB virus type C (GBV-C) and hepatitis G virus (HGV) can be classified into three major genotypes. In addition to this classification, a novel genotype of GBV-C/HGV was identified and designated type 4. However, genotyping of GBV-C/HGV has been hampered by the lack of suitable assays. In this study, a simple and precise genotyping system based on PCR using the type-specific primers was developed for the determination of genotypes 1, 2, 3, and 4 of GBV-C/HGV. A total of 235 serum samples obtained from 11 different countries were tested by our PCR genotyping system of GBV-C/HGV. The results revealed that type 1 was prevalent mainly in Ghana, type 2 was prevalent in the USA, Spain, Egypt, Nepal and Myanmar, type 3 was prevalent in Japan and Bolivia, and type 4 was prevalent in Vietnam and Myanmar among the countries investigated in the present study. To confirm the specificity of the results of genotyping by PCR, phylogenetic analysis in the 5'-untranslated region of GBV-C/HGV was undertaken in 99 serum samples. By this analysis, the specificity of the genotyping system by PCR was confirmed. This assay system may be useful for rapid typing of GBV-C/HGV RNA when either epidemiological or transmission studies of this agent are carried out.