Molecular epidemiology of GII noroviruses in outpatients with acute gastroenteritis in Shandong Province, China.

Noroviruses have been recognized as the most important causative agents of acute gastroenteritis. The present study was carried out to investigate the molecular epidemiological features of genotype II (GII) norovirus in outpatients with acute gastroenteritis in Shandong province in China from July 2017 to June 2018. In total, 151 (10.30%) samples were positive for NoV GII strains by RT-PCR. Eight genotypes were detected: GII.2, GII.3, GII.4, GII.6, GII.7, GII.12, GII.13 and GII.17. GII.4 (43.71%) was the most prevalent genotype, and the dominant strains belonged to the group of Sydney-2012 strains. GII.17 (27.15%), which has become the main cause of outbreaks of acute gastroenteritis in China, also accounted for a high proportion. Meanwhile, three recombinant types (GII.P17-GII.7, GII.P3-GII.4 and GII.P12-GII.4) were observed and authenticated using Simplot software. The results showed that GII norovirus was the main cause of acute gastroenteritis in Shandong province. GII.4 and GII.17 were the dominant genotypes. Continuous observation and identification of emerging genotypes are necessary for understanding the evolution of the virus, control of infection, and development of vaccines.