Longitudinal analysis of VP7 gene of group A human rotavirus G2P[4] strains circulating in the pre-vaccine era in Sapporo, Japan from 1991 to 2011.

Sequence analysis of the VP7 gene in 23 group A human rotavirus G2P[4] strains obtained during 1991-2011, that is, the pre-vaccine era, in Sapporo, Japan showed considerable genetic diversity, mainly in variable regions. Recent G2P[4] epidemic strains were located in sublineage IVa with a distinctive substitution of D96N. This study provides background data on the genetic variability of G2P[4] rotavirus-VP7 gene prior to the widespread use of rotavirus vaccines in Japan.