Immunoscreening and Identification of Chinese HCV Genomic cDNA ? gt11 Library / 第二军医大学学报

ABSTRACT

Hepatitis C virus (HCV) is a major causative agent for sporadic and post-transfusion hepatitis, which frequently progresses into chronic hepatitis, liver cirrhosis and hepatocellular carcinoma. In order to clarify the genomic variations and the structural characteristics of Chinese HCV isolate, we extracted HCV genomic RNA from plasma specimens of Chinese hepatitis C (HC) patients, reverse-transcribed to HCV cDNA with random primers and constructed successfully an HCV cDNA R gt11 library of Chinese type. Two positive clones (Q349 and Q653) were selected by immunoscreening from the library and subcloned into plasmid vector pUC18. Sequence analyses indicated that Q349 was derived from core region (positions 554-902) of HCV genome while Q653 was from NS3 region (positions 4175-4827) corresponding with the prototype HCV nucleotide sequence. The homologies of Q349 and Q653 with the equivalent sequences of HCV prototype were 86.8% and 80.2% at the nucleotide level, and 97.3% and 93.1% at the amino acid level, respectively. It was found that Chinese HCV clones had higher homologies with Japanese HCV isolates, and should belong to HCV group II. Specificity test proved that the encoded peptides of the 2 Chinese HCV cDNA clones reacted specifically with sera from HC patients and had no reaction with sera from healthy individuals. More importantly, clone Q653 showed higher positive reaction rates with Chinese HC sera (95.8%) than those with Japanese ones (85.7%), which strongly suggests that the sequences from Chinese HCV genome (especially from NS regions) would be more suitable for primer designing or peptide synthesis for the use in the detection of HCV infection among Chinese people.