A novel norovirus GII.17 lineage contributed to adult gastroenteritis in Shanghai, China, during the winter of 2014–2015

Abstract

Norovirus (NoV) is now recognized as a leading cause of nonbacterial acute gastroenteritis; however, the NoV GII.17 genotype has rarely been reported as the predominant genotype in clinical diarrhea cases. During the winter of 2014–2015, the GII.17 genotype, together with the NoV GII.4 genotype, dominated in sporadic adult patients with gastroenteritis in Shanghai. Phylogenetic analysis based on full-length VP1 amino acid sequences showed that the GII.17 strains that emerged in Shanghai have close evolutionary relationships with strains recently collected in the Hong Kong area, Guangdong province of China, and Japan during the same period. This cluster in the phylogenetic tree may represent a novel NoV GII.17 lineage recently circulating in East Asia. Pairwise distances between clusters also revealed the evolution of the NoV GII.17 genotype in previous decades. Our study emphasizes the importance of combined surveillance of NoV-associated infections.

Figure 1

Genotype distribution of NoV genogroupII (GII) in sporadic patients with NoV infection from 2014–2015 in Shanghai, China. (A) Genogroup II of GII.2, GII.3, GII.4 Sydney_2012, GII.6, GII.13, and GII.17 in all patients. (B) Genogroup II of GII.2, GII.4 Sydney_2012, GII.6, GII.13, and GII.17 in adult patients. (C) Genogroup II of GII.3, GII.4, and GII.6 in pediatric patients.

Figure 2

Monthly detection rate of NoV in adult outpatients (≥15 years of age) with acute gastroenteritis from 2014 to 2015 in Shanghai, China.

Figure 3

Phylogenetic analysis of full-length VP1 amino acid sequences of the NoV GII.17 genotype. The full-length VP1 sequences of three representative NoV GII.17 strains from November and December 2014 and January 2015 were sequenced (primers listed in Supplementary Table S1; GenBank accession NOs KP864102–KP864104). The GenBank accession numbers of the NoV GII.17 reference strains are displayed in the phylogenetic tree, followed by the genotypes, years, and countries.

Figure 4

Amino acid variations in the VP1 protein of NoV GII.17 strains. Amino acid sequence alignment of the VP1 protein was performed for representative strains from each of the GII.17 clusters described in Figure 3. Amino acid substitutions and indel mutations are indicated with different colors. The shell (S) domain, protruding (P) domain, and five speculated epitopes (A–E) are also labeled in the figure. The epitopes are putatively identified based on analogy to putative GII.4 epitopes.