[Molecular characteristics of norovirus in 3 outbreak-episodes of gastroenteritis in Zhejiang from 2008 to 2009].

Objective: To study the molecular characteristic of norovirus in 3 outbreaks of gastroenteritis in Zhejiang province.

Methods: During January 2008 and December 2009, fecal specimens of patients were collected from 3 outbreaks of acute viral gastroenteritis. Noroviruses were detected by Real-time RT-PCR. Part of the positive samples were randomly selected and detected by RT-PCR. PCR products were sequenced. Sequence analysis was undertaken based on partial sequence of RNA dependent RNA polymerase (RdRp) and capsid protein gene. Some positive samples were amplified by 3'RACE (rapid amplification of cDNA 3'ends), 3200 bp in length. The exact whole ORF2, ORF3 and 3'untranslation regions (UTR) gene of norovirus were identified.

Results: There were in total 3 outbreaks of viral gastroenteritis caused by norovirus being reported. A total of 62 stools were obtained from cases with acute gastroenteritis. Noroviruses were detected in 41 cases including 27 strains of genogroup I norovirus and 9 strains of genogroup II norovirus, 5 strains of genogroup I + II norovirus. Four genotypes including GI.8, GII.b, GI.2/GI.6 recombination together with co-infection of GI.8 and GII.b were detected.

Conclusion: Norovirus was confirmed as the major cause of outbreaks of viral gastroenteritis in Zhejiang province and multiple genotype of norovirus were identified from the outbreaks. It was the first time to have found a recombinant of GI.6 capsid and GI.2 polymerase norovirus as well as the co-infection of GI.8 and GII.b norovirus in the same sample.