Genetic analysis of noroviruses associated with sporadic gastroenteritis during winter in Guangzhou, China.

Noroviruses are regarded as the major causes of acute gastroenteritis worldwide, but their prevalence in sporadic diarrhea in South China remains unclear. This study was performed to characterize the genotypes of circulating norovirus strains associated with sporadic diarrhea cases in Guangzhou from November 2010 to January 2011. Among fecal specimens collected from 89 patients with acute diarrhea, nine samples (10.11%) were norovirus positive and 32 samples (35.96%) were rotavirus positive. The partial polymerase and the capsid regions of these norovirus samples were sequenced and phylogenetically analyzed. Three genotypes (GII.4, GII.6, and GII.b/GII.3) were identified, among which GII.4-2006b was the most predominant genotype (4/9, 44.4%), followed by GII.6 (3/9, 33.3%). A novel GII.4-2010 variant was first detected in China. Furthermore, the near full-length genome of the GZ2010-L26 strain, which belonged to GII.4-2006b, was sequenced and analyzed. Thus, the results of this study suggested that, second to rotavirus, noroviruses are the important pathogens responsible for sporadic acute gastroenteritis during winter in Guangzhou, and the GII.4-2006b variant remains the predominant genotype.