Gene duplications in poliovirion RNA.

Two intragenomic homologous sequence pairs were detected in poliovirion type 1 (Mahoney) RNA. An RNA sequence region N3729-N4118 (by the numbering of Kitamura et al. (ref. 1)) coding for P2-3b was found to share 39% identical bases in 360 aligned positions with another region N5007-N5366 encoding P2-X and P3-1b. An RNA segment N3381-N3558 coding for the N-terminal portion of P2-3b was shown to have 42% identical bases in 178 positions aligned with N5979 -N6161 which encodes the N-terminal sequence of P3-4b (RNA-dependent RNA polymerase). A statistical technique developed here for evaluating nucleotide sequence homologies demonstrated highly significant homology levels, P less than 10(-8) for the former alignment and P less than 10(-5) for the latter.