Over 15000 molecular clones of the E1E2 and NS5A regions (L = 472 and L = 743, respectively) obtained from patient serum samples were sequenced. The observed number of nonsense mutations was divided by the number of possible nonsense substitutions in these genes, which was T_s = 113 on average (1), yielding m_s/n/c = 1.2 ´ 10^-4. As above, this estimate assumes that all observed nonsense mutations are truly lethal and should be taken as an upper-limit value because suppression of stop codons, complementation or RT-PCR errors were not ruled out.

1. Cuevas, J. M., F. Gonzalez-Candelas, A. Moya, and R. Sanjuán. 2009. The effect of ribavirin on the mutation rate and spectrum of Hepatitis C virus in vivo. J. Virol. 83:5760-5764.