Infection status and genotype characteristics of GⅠ norovirus in acute gastroenteritis cases in Huzhou, Zhejiang, 2017–2018

ObjectiveTo understand the infection status and genotype characteristics of GⅠ norovirus in acute gastroenteritis cases in Huzhou, Zhejiang province.

MethodsA total of 1 259 stool samples of acute gastroenteritis cases diagnosed in two sentinel hospitals in Huzhou from April 2017 to June 2018 were collected. The extracted viral RNA was subjected to GⅠ and GⅡ norovirus nucleic acid detections by using real-time quantitative reverse transcription polymerase chain reaction( RT-PCR). GⅠ positive samples were amplified and sequenced by RT-PCR in RdRp and VP1 regions. The genotyping of norovirus was confirmed by phylogenetic analysis and online typing tools.

ResultsA total of 171 stool samples were norovirus nucleic acid positive, the positive rate was 13.58%. The positive rates of GⅡ and GI noroviruses were 11.83% (149/1 259) and 2.70% (34/1 259), respectively, GⅡ was the main genotype detected. GⅠ norovirus was mainly detected in the first half of 2018. The positive detection rate of GⅠ norovirus in each month from February to June 2018 was higher than the average detection rate of GⅠ during the surveillance period. The genotyping results showed that the GⅠ norovirus detected in 2018 included GⅠ.P4-GⅠ.5, GⅠ.P2-GⅠ.2, GⅠ.P1-GⅠ.1, GⅠ.Pd-GⅠ.3, GⅠ.P4-GⅠ.4 and GⅠ.P2-GⅠ.5, in which GⅠ.P4-GⅠ.5, GⅠ.P2-GⅠ.5 and GⅠ.Pd-GⅠ.3 recombinant norovirus were detected for the first time in Huzhou.

ConclusionThe genotypes of GⅠ noroviruses circulating in Huzhou are diverse and the recombination phenomenon is obvious. It is necessary to strengthen the molecular epidemiological surveillance for GⅠ norovirus for the timely detection of variants or recombinant strains.