Characterization of norovirus in adults with acute gastroenteritis in Shunyi district of Beijing from 2014 to 2015

Abstract

Objective To investigate the infection and genetic characteristics of norovirus in adults with acute gastroenteritis in Shunyi district of Beijing. Methods From January 2014 to December 2015, stool specimens and clinical data were collected from 240 adults with acute gastroenteritis from enteric clinics in Shunyi district of Beijing. Norovirus was detected by Real-time PCR. For norovirus-positive samples, reverse transcription-PCR(RT-PCR)was performed to amplify RNA-dependent RNA polymerase(RdRp)gene fragment. The RdRp regions of norovirus- positive samples were sequenced and performed genotype analysis. Results The positive rate of norovirus was 23.33%(56/240). GⅡ group was the predominant genogroup(20.83%, 50/240), followed by GⅠ group(2.50%, 6/240). There was no significant difference in the norovirus positive rate between male and female(χ2=0.21, P=0.65). Norovirus could be detected throughout the year, and the prevalent peak was between November and March of the following year, from 2014 to 2015. The sequence analysis of RdRp regions showed that GⅡ.4(37.50%, 6/16)was the predominant epidemic genotype of norovirus during 2014, and GⅡ. 17(71.43%, 20/28)became the predominant one during 2015. The 11 GⅡ.4 sequences of RdRp region obtained in this experiment and the GⅡ.4 reference strains which were isolated before 2009 were not in the same phylogenetic branch, but the GⅡ.4 experiment sequences and the reference strains which were isolated in recent years such as Sydney NSW0514 strain were in the same phylogenetic branch. The gene homologies of the GⅡ.4 experiment sequences and the older reference strains were more different than the experiment sequences and the younger reference strains. The 23 GⅡ.17 sequences of RdRp region obtained in this experiment were in the same phylogenetic branch with all the GⅡ.17 reference strains selected. There were some nucleotide differences between the experiment sequences and the GⅡ.17 reference strains. All the experiment sequences have no amino acid differences with all the GⅡ.17 reference strains except 14115 and 15017. Conclusions The predominant epidemic genotype of norovirus was GⅡ.4 during 2014, which turned to GⅡ. 17 during 2015 in adults with acute gastroenteritis in Shunyi District of Beijing. There were more than one norovirus genotype co-epidemic in Shunyi from 2014 to 2015. Key words: Norovirus; Acute gastroenteritis; Genotype