Evaluation of accumulation of hepatitis C virus mutations in a chronicallyinfected chimpanzee: Comparison of the core, E1, HVR1, and NS5b regions

Four hepatitis C virus genome regions (the core, E1, HVR1, and NS5b) were a mplified and sequenced from yearly samples obtained from a chronically infe cted chimpanzee over a rt-year span. Nucleotide substitutions were found to accumulate in the core, E1, and HVR1 regions during the course of chronic infection; substitutions within the NS5b region were not detected for the f irst 8 years and were found to be minimal during the last 4 years. The rate of accumulation of mutations in the core and El regions, based on a direct comparison between the first 1979 sequence and the last 1990 sequence, was 1.120 x 10(-3), while phylogenetic ancestral comparison using the 12 yearl y sequences showed a rate of 0.816 x 10-3 bases per site per year, Temporal evaluation of the sequences revealed that there appeared to be periods in which substitutions accumulated and became fixed, followed by periods with relative stasis or random substitutions that did not persist. Synonymous an d nonsynonymous substitutions within the core, E1, and HVR1 regions were al so analyzed. In the core and El regions, synonymous substitutions predomina ted and gradually increased over time. However, within the ENR1 region, non synonymous substitutions predominated but gradually decreased over time.