OBJECTIVETo identify the etiological agent of acute gastroenteritis outbreaks occurred in 6 hospitals in Beijing from November to the end of 2006 and to characterize the virus on molecular biology.

METHODSRota-strip was used to detect rotavirus antigen and PAGE for rotavirus RNA in stool specimens collected from patients with gastroenteritis at the first stage. Reverse transcription-polymerase chain reaction(RT-PCR) was performed to detect Norovirus in stool specimens. Full length of Norovirus VP1 genes were amplified from Norovirus positive samples by RT-PCR and sequenced after the gene was cloned into vector pUCm-T. The sequences of partial VP1 gene at the 5' end of full-length gene were obtained from 2 of the Norovirus positive samples to analyze the relationship of these viruses at molecular level.

RESULTSNorovirus was detected in 17 of the 30 stool specimens with an overall positive rate of 56.7%. Positive rates were all above 42.9% in specimens collected from each of the hospital. Sequence analysis on one of the full-length of VP1 amplified by RT-PCR from one of the positive specimens NV8-Beijing indicated that it belonged to G II-4 genotype. This strain shared 94.8% and 95.2% identities over the complete major capsid gene to Lanzhou strain form Lanzhou China and Farmington Hill strain from USA which belonged to G II-4 genotype, but only 91.1% identity to the CR2905 from Beijing China identified from specimen collected in late 2004. The sequences of 5' end of VP1 genes amplified from other two samples collected from different hospitals showed only one nucleotide mutation compared to NV8-Beijing in the correspondence part, indicating that these two strains also belonged to G II-4 genotype.

CONCLUSIONNorovirus was the etiological agent causing outbreaks of acute gastroenteritis in hospitals in Beijing and the strain with G II-4 genotype which was closer to the Lanzhou and Farmington strains than Beijing strains identified in 2004.