Background
The HCV NS5B RNA polymerase is a new target for drug development for HCV disease. Valopicitabine (NM283), the prodrug of 2'-C-Methylcytidine (NM107), has been the most clinically advanced NS5B nucleoside inhibitor. Nucleoside inhibitors exhibit similar activity among genotype 1 strains, but their efficacy among other genotypes is largely unknown. In this study NS5B amino acid polymorphisms in positions affecting activity and drug efficacy were investigated in sequences of all HCV genotypes.