Molecular epidemiology of norovirus among infants with diarrhea in Chaoyang district, Beijing from 2011 to 2017

Objective To investigate the genetic characteristics of human norovirus (NoV) among infants under 5 years of age with diarrhea in Chaoyang District, Beijing from 2011 to 2017. Methods NoV-positive stool samples were collected from 2011 to 2017 in this region. The partial RdRp and VP1 genes were amplified and sequenced. Multi-sequence alignment was performed and phylogenetic tree was constructed using Mega software. Results A total of 151 samples were sequenced and analyzed. The ratio of male and female was 2.28∶1 with mean age of 1.72 years. Fourteen NoV subtypes were detected, including GII.Pe/GII.4 (47.68%), GII.P12/GII.3 (20.53%), GII.P4/GII.4 (17.22%), GII.P16/GII.2 (3.31%), GII.P12/GII.12 (1.99%), GII.P17/GII.17 (1.99%), GII.P16/GII.13 (1.32%), GII.P7/GII.7 (1.32%), GII.P7/GII.6 (1.32%), GII.P2/GII.2 (0.66%), GII.P21/GII.21 (0.66%), GII.Pg/GII.12 (0.66%), GI.Pa/GI.3 (0.66%) and GI.P6/GI.6 (0.66%). Conclusions NoV genetic diversity was found among infants under 5 with diarrhea in Chaoyang district, Beijing. The subtypes from surveillance and those from epidemics occurred in chronological order. The surveillance should be strengthened for early detection of new subtype for monitoring the epidemic and vaccine design. Key words: Norovirus; Viral diarrhea; Genotype; Phylogenetic analysis