Abstract
There are limited data on diversity within the hepatitis C virus polymerase (NS5B). In concordance with its key functional role during the life cycle, NS5B intrapatient variability was low. Moreover, differences between NS5B nonsynonymous (dN) and synonymous (dS) mutation rates (dN - dS) were positively correlated with CD4 cell count, while nonsynonymous mutations were strongly correlated with reduced replication in vivo.