Base transitions and base transversions seen in mutations among various types of the hepatitis C viral genome.

We counted base transitions (Ts) and transversions (Tv) in mutations among various types of hepatitis C virus (HCV) sequences. The Ts/Tv ratio was useful for distinguishing the (geno)type of the compared HCV sequences, since the ratio was 4.0 or more among sequences of the same type, while it was less than 2.0 among sequences of different types. This observation reflects the evolutionary pathway of HCV in which Tv accumulate among distant genomes by mechanisms including multiple base substitutions.