Transition of genotypes associated with norovirus gastroenteritis outbreaks in a limited area of Japan, Hiroshima Prefecture, during eight epidemic seasons

The transition of genotypes implicated in 102 NoV gastroenteritis outbreaks in Hiroshima Prefecture, Japan, during eight epidemic seasons was investigated. Eighteen genotypes were implicated in the outbreaks, with the chronological characteristics as in GII.3, GII.4, GII.5 and GII.12. In GII.4 variants, amino acid changes and positively selected sites were of note and significantly concentrated in the surface-exposed P2 subdomain of the VP1 protein. Notably, variant-specific epitopes at which positively selected sites are located may be significant for distinguishing a new GII.4 variant. The interaction of these genetic changes with developing immunity seems to influence NoV epidemics.