Molecular epidemiology of norovirus associated with acute gastroenteritis in Taizhou, China: A retrospective study.

BACKGROUND

Norovirus (NoV) is recognized as a leading global cause of viral acute gastroenteritis (AGE). To better understand the prevalence and genotypic patterns of NoV infection in Southeast China, we conducted a retrospective study of diarrheal syndrome surveillance of NoV and analyzed the epidemiological characteristics of AGE cases and phylogenetic evolution of NoV strains.

METHODS

1464 AGE patients in two diarrhea surveillance sentinel hospitals were sampled during 2016 and 2017. NoV Positive samples were genotyped by ORF1/ORF2 overlapping regional gene sequencing. Sequences analyses of the NoV genotypes were confirmed by online NoV Genotyping Tool and the phylogenetic analysis was constructed by MEGA 7.0.

RESULTS

139 (9.49%) of the AGE specimens were NoV positive. The GII strain was the main geno-group in NoV infected patients. At least 12 NoV genotypes and seven recombinant strains were detected. Major NoV genotypic transformations were GII.Pe/GII.4, GII.P17/GII.17 and GII.Pe/GII.17 in 2016 to GII.P16/GII.2, GII.P17/GII.17 and GII.Pe/GII.4 in 2017. Phylogenetic analysis showed that GII.P16/GII.2 recombinant strains clustered with those detected in the USA, Russia and Japan in 2016.

CONCLUSION

We characterized the molecular epidemiology of NoV infection in AGE patients during 2016-2017. The main three NoV GII genotypes circulating in the population of Taizhou were GII.P17/GII.17, GII.Pe/GII.4 and GII.P16/GII.2.The GII.P16/GII.2 genotype has become the predominant strain since first quarter 2017. Monitoring of the NoV genotypic shift is important for the prevention and control of AGE.