Full-genome sequence analysis of an uncommon norovirus genotype, GII.21, from South Korea

Full-genome sequences of GII.13[P21] recombinant norovirus strains from an outbreak in Changsha, China

On 31 March 2019, 68 school students suffered from vomiting, diarrhea, and abdominal pain after participating in a group activity at a commercial park. In this outbreak, multiple norovirus genotypes were observed, including GII.2[P16], GII.17[P17], and GII.13[P21]. Further, we determined the full-genome sequences of two strains of GII.13[P21] recombinant noroviruses, which were 7434 nt long. Phylogenetic analysis based on open reading frames (ORFs) 1 and 2 revealed that these recombinants were related to stains of different genotypes from different countries. The full genome nucleotide sequences of the two isolates were 97.0% and 98.0% identical to those of strains from London and Thailand, respectively. Simplot analysis revealed the presence of a break point at nt 5059 in the ORF1 region. The histo-blood group antigen binding sites were conserved in both recombinant viruses. Our findings not only provide valuable genetic information about a recombinant norovirus but also contribute to our general understanding of the evolution, genetic diversity, and distribution of noroviruses.

Complete sequence analysis of human norovirus GII.17 detected in South Korea

Norovirus, a major cause of gastroenteritis in people of all ages worldwide, was first reported in South Korea in 1999. The most common causal agents of pediatric acute gastroenteritis are norovirus and rotavirus. While vaccination has reduced the pediatric rotavirus infection rate, norovirus vaccines have not been developed. Therefore, prediction and prevention of norovirus are very important. Norovirus is divided into genogroups GI-GVII, with GII.4 being the most prevalent. However, in 2012-2013, GII.17 showed a higher incidence than GII.4 and a novel variant, GII.P17-GII.17, appeared. In this study, 204 stool samples collected in 2013-2014 were screened by reverse transcriptase-polymerase chain reaction; 11 GI (5.39%) and 45 GII (22.06%) noroviruses were identified. GI.4, GI.5, GII.4, GII.6 and GII.17 were detected. The whole genomes of the three norovirus GII.17 were sequenced. The whole genome of GII.17 consists of three open reading frames of 5109, 1623 and 780 bp. Compared with 20 GII.17 strains isolated in other countries, we observed numerous changes in the protruding P2 domain of VP1 in the Korean GII.17 viruses. Our study provided genome information that might aid in epidemic prevention, epidemiology studies and vaccine development.