Objective: To explore the epidemiologic characteristics of noroviruses isolated in patients with acute gastroenteritis in Hangzhou between March 2014 and April 2015.
Methods: Stool specimens and clinical data were collected from 1 109 patients with acute gastroenteritis. Specimens were detected for noroviruses with GⅠand GⅡsubtypes by one-step double real-time RT-PCR. Some of the positive specimens were then randomly selected and amplified by multiplex RT-PCR. Those positive PCR products were sequenced and analyzed phylogenetically for testing the partial capsids of noroviruses.
Results: Of the 1 109 stool specimens, positive rate of noroviruses was 26.87% (298/1 109). GⅡgenotype was the major viruses with the proportion as 25.52% (283/1 109), while 1.35% (15/1 109) belonged to GⅠgenotypes. There was no significant difference in the noroviruses detection rate of the different genders (P>0.05). However, in different age groups, GⅡgenotypes were predominant types of noroviruses, and the positive rates of GⅡgenotypes were 16.94% (<5 years-old), 19.45% (5-18 years-old) and 32.26% (≥18 years-old), respectively. In different seasons, noroviruses could be detected all year round, with positive rate as 29.67%-37.08% in the highly epidemic seasons (between December and March of the following year). The distribution trends were seen certain difference between noroviruses-GⅡand GⅠtypes. Additionally, results from the sequence analysis demonstrated that GⅡ-4 genotype was the prevalent strain of GⅡ genotypes, clustered into GⅡ-4/Sydney (46.43%, 13/28) and GⅡ-4/2006b (25.0%, 7/28), while GⅠstrains clustered into GⅠ-1.
Conclusion: Noroviruses appeared one of the major pathogens, leading to acute gastroenteritis. G Ⅱgenotypes of noroviruses, especially the G Ⅱ-4/Sydney variant strains and GⅡ-4/2006b variant strains, were considered to be the prevalent strains prevailed in Hangzhou areas from 2014 to 2015.