Comparison of genetic characteristics in the evolution of Norovirus GII.4 and GII.17.

The genetic characteristics of Norovirus GII.17 were evaluated. Phylogenetic analysis and comparisons of amino acid (Aa) substitutions and nonsynonymous (NS) substitutions/site/year were performed. The complete VP1 sequence of Tokyo/27-3/1976 clustered independently with GII.P17_GII.17 strains. Aa substitutions were mainly accumulated in the P2 domain. NS substitutions/site/year for Tokyo/27-3/1976 compared to Kawasaki323/2014 and Kawasaki308/2015 were 0.57 × 10-3 and 0.78 × 10-3 , respectively; for GII.4 Sydney/NSW0514/2012 compared to CHDC2094/1974 and CHDC5191/1974 were 0.93 × 10-3 and 1.06 × 10-3 , respectively. These findings imply that evolutionary diversity in the VP1 of GII.17 might be strictly constrained in contrast to that of GII.4.