Sequence variation of the P gene among mumps virus strains.

We have determined nucleotide sequences of a 183-nucleotide long region of the P gene of 10 mumps virus strains after gene amplification mediated by DNA polymerase catalyzed chain reaction (PCR) and have compared them with those of two strains which had been reported earlier (K. Takeuchi et al., J. Gen. Virol., 69, 2043-2049 (1988]. It was shown that mutation is generally noncumulative, i.e., most nucleotide substitutions in earlier strains do not appear in later strains. Viruses of different lineages appeared to cocirculate, but the comparison of American and Japanese strains suggested that those isolated in one country are more closely related to each other than to those isolated in the other country.