cDNA cloning and sequence analysis of hepatitis G virus genome isolated from a Chinese blood donor

Objective To obtain full-length sequence of a Chinese hepatitis G virus (HG V) strain (HGVch) and investigate the genetic characteristic of HGVch and i ts identity to other isolates. Methods Reverse transcription (RT) and nested-PCR were used to screen HGV R NA positive serum and amplify cDNA fragments. A positive serum without know n hepatitis virus markers was selected for isolating HGV RNA template. The HGV genome was divided into 12 overlapping fragments and directly cloned in to pGEM-T vector. Sequences were determined by dideoxy terminus-end method of DNA sequencing and then analyzed by computer. Results The twelve fragments of HGVch cover 9213 nucleotides in length, con taining a large opera reading frame (ORF) encoding 2873 animo acids polypro tein that began with a methonine residue and ended at termination codon. HG Vch is about 86.5% - 89.5% identical to other known HGV isolates at the nuc leotide level and about 93.9% - 96.2% at the deduced animo acid level. Conclusion HGV is a non-A-E hepatitis causal agent, proved to be related wi th posttransfusion hepatitis in all over the world. Chinese HGV isolate has very close relationship to other isolates from Africa, Europe, Japan, with out significant difference across the entire genome. It is suggested that t he sequences of HGV isolates are very conservative and the evolution is ver y slow.