The characteristic of codon usage pattern and its evolution of hepatitis C virus

► Mutational pressure was the dominant factor accounting for HCV codon usage variation. ► Selection pressure also accounted for HCV codon usage pattern. ► The HCV codon usage was a mixture of coincidence and antagonism to that of its host. ► The codon usage bias of the genotype 1 of HCV was stronger than the other genotype. ► The codon usage bias between sub-genotype 1a and 1b strains was different.