Prevalence and Genetic Diversity of Norovirus in Outpatient Children with Acute Diarrhea in Shanghai, China

This study aimed to investigate the epidemiology of norovirus (NoV) associated-diarrhea among pediatric outpatients in Shanghai, and characterize the genotypes of circulating NoV strain. Stool samples were collected from 910 children with non-dysenteric diarrhea between August 2008 and July 2009. One-step real-time RT-PCR was used to screen for NoV genogroup I (GI) and genogroup II (GII). Genotypes were classified by sequence analysis of partial capsid and RNA-dependent RNA polymerase (RdRp) fragments. NoV was detected year round with high activity in July, August, September, and October. Of 910 specimens, 165 (18.13%) were positive for NoV; 4 (2.42%) were GI, and 161 (97.58%) were GII. Based on capsid sequences, 8 different genotypes were identified for 114 NoV strains, including GII.4 2006b (57.89%), GII.3 (30.70%), GII.6 (4.39%), GII.12 (3.51%), GII.14, GII.2, GI.4, and GI.5 (0.88% each). Based on the RdRp sequences of 86 NoV strains, NoV was genotyped as GII.4 (62.79%), GII.12 (30.23%), GII.g (2.33%), GII.2 (1.16%), GII.6 (1.16%), GII.7 (1.16%), and GI.4 (1.16%). The RdRp genotypes of 30 strains were inconsistent with the capsid genotypes, indicating potential NoV recombinants.