Comparison between subgenomic replicons of hepatitis C virus genotypes 2a (JFH-1) and 1b (Con1 NK5.1).

Although replicon systems for hepatitis C virus (HCV) recently developed have enabled the replication of HCV in cultured cells, limited genotypes are available for them. We have isolated HCV cDNA of genotype 2a (JFH-1 strain) from serum of a patient with fulminant hepatitis. A subgenomic replicon of JFH-1 was constructed and compared with the HCV replicon of genotype 1b (Con1 NK5.1) which possessed adaptive mutations. Huh7 cells transfected with replicon RNAs that had been transcribed in vitro were cultured in the presence of neomycin sulfate (G418), and selected colonies were isolated and expanded. Then, growth rates and replication of HCV RNA were evaluated on isolated cells hosting replicons. Saturation densities were lower for cells propagating JFH-1 than Con1 NK5.1 or untransfected Huh7 cells, and the mean doubling time was longer for JFH-1 than for Huh7 cells. Levels of HCV RNA replication in isolated clones were similar between JFH-1 and Con1 NK5.1 cells. Replication of RNA decreased reciprocally with cell densities in both JFH-1 and Con1 NK5.1 cells. The replication of HCV RNA was more resistant to interferon-alpha in JFH-1 than in Con1 NK5.1 cells based on the comparison of an inhibitory concentration of 50%. In conclusion, we found differences between HCV replicon clones of genotypes 1b and 2a. However, these differences may result from strain-specific characteristics, such as the source of HCV, rather than characteristics of distinct genotypes. Therefore, further investigation may be needed on more HCV isolates of diverse genotypes. Copyright (c) 2006 S. Karger AG, Basel.