Objective: To analyze the sequence variation in the nonstructural region 5 b(NS5 b) of hepatitis C virus (HCV) of China.
Methods: Complementary DNA fragments from sera of 49 Chinese patients were amplified by reverse transcription nested polymerase chain reaction (RT-nested-PCR) and the products were cloned and sequenced.
Results: 33 clones belonged to genotype 1 b and 16 clones were genotype 2 a. Several conserved nucleotide sites were found to be different from those of Japanese isolates though they belonged to an identical genotype. Comparison of average homology among the 33 clones of genotype 1 b and the 16 clones of genotype 2 a indicated that the average homology among genotype 2 a was lower than that among genotype 1 b. A deletion of three nucleotides and a frame-shift, resulting from the introduction of an in-frame stop codon, were firstly observed in the NS5 b region.
Conclusion: The nucleotide sequences of different HCV isolates of a same subtype may possibly possess the characteristics for different geographical distribution and so a definite epidemic HCV strain may emerge from a definite area.