Complete nucleotide sequence analysis of the norovirus GII.17: A newly emerging and dominant variant in China, 2015.

Norovirus is an important pathogen which accounts for majority of the viral related acute gastroenteritis. Recently, a variant of genotype GII.17 was reported to be predominant over GII.4 and accounted for several acute gastroenteritis outbreaks in Asia. In the current study, the full genome of a norovirus strain ZHITHC-12 isolated during this outbreak period in China was identified and characterized. The viral genome was 7557 nucleotides in length and a phylogenetic analysis based on full length genome sequences indicated that ZHITHC-12 belonged to GII.17 genotype. A further phylogenetic analysis based on all available polymerase and capsid sequences showed that ZHITHC-12 was in Cluster III on both phylogenetic trees and grouped with other strains also isolated during 2013 to 2015. Moreover, homology modeling analysis based on GII norovirus capsid 5BSX template revealed that substitutions, mutations, and more importantly, deletions and insertions, occurred at or near the putative epitopes and histo-blood group antigen (HBGA) binding sites in its protruding P2 domain, which might confer new antigenic or biological properties for this novel variant. In summary, the first full genome and capsid protein structure of a novel norovirus GII.17 variant isolated in China was extensively characterized. The data would be helpful not only for the epidemiology study, but also for the diagnostic tool development and effective vaccine design in the future.