Clinical and molecular epidemiology of norovirus infection in adults with acute gastroenteritis in Ji'nan, China.

Acute gastroenteritis caused by human noroviruses (NoVs) has become an important public health problem worldwide. This study was carried out to investigate the rates of NoV infections and the genetic characteristics of NoVs in adult outpatients with acute gastroenteritis in Ji'nan, a large eastern city in China. A total of 480 fecal samples were collected from outpatients at the Shandong University Qilu Hospital between June 2010 and May 2011. Of the collected samples, 42 (42/480, 8.75 %) were positive for NoVs by RT-PCR, and seven different genotypes were identified: GI-1, GI-4, GII-1, GII-3, GII-4, GII-6 and GII-13, of which GII-4 was the most prevalent (29/42, 69.0 %). Phylogenetic and Simplot analyses showed that three recombinant strains were detected: two GII-4 polymerase/GII-3 capsid recombinants and one GII-6 polymerase/GII-4 capsid recombinant. This study indicated that NoV was a common causative agent of sporadic acute gastroenteritis in adults in Ji'nan, China, and that NoV GII-4 was the predominant strain during this period. Three recombinant strains were identified in which GII-6 polymerase/GII-4 capsid was detected for the first time in China.