Genetic diversity of norovirus in schools of a certain district in Hangzhou, 2021−2024

Objective  To investigate the molecular epidemioloGⅠcal characteristics of norovirus in school infections in a certain district of Hangzhou from 2021 to 2024.

Methods  Samples of norovirus infection cases in schools from 2021 to 2024 were collected, and norovirus was genotyped by reverse transcription polymerase chain reaction (RT-PCR) . The positive samples were subjected to first- or second- generation sequencing for genomic amplification and sequence analysis .

Results  From 2021 to 2024, a total of 593 specimens from 70 gastroenteritis infection events in schools were collected. Among them, 379 norovirus samples were detected as positive and the viral genotypes of 276 specimens were successfully measured. Norovirus type Ⅰ was involved in 12 outbreaks, and type GⅡ was involved in 57 outbreaks (including one of mixed infection of type GⅠ/ type GⅡ), with a total of 15 genotypes discovered . Genotypes GⅡ.17P17, GⅡ.3P12, and GⅡ.7P7 are the main epidemic strains. The homology among samples of the same genotype for different events ranged from 89.2% to 100.0% , the homology among samples of the same genotype in the same event ranged from 92.5% to 100.0%.

Conclusion  Noroviruses circulating in schools in this district of Hangzhou from 2021 to 2024 exhibited significant genetic diversity, and continuous surveillance revealed a shift in predominant genotypes over different years. Ongoing molecular surveillance of norovirus is essential to provide a scientific basis for early warning of potential outbreaks.