OBJECTIVETo investigate the molecular characteristics of noroviruses detected in Beijing.

METHODSFrom January to March 2007, cases from both outbreaks and sporadic episodes of acute nonbacterial gastroenteritis were investigated in Beijing, and the fecal specimens of the patients were collected. Noroviruses were detected by a reverse transcription polymerase chain reaction (RT-PCR), and then the PCR products were cloned and sequenced.

RESULTSA total of 27 positive cases were identified as caused by noroviruses among the 38 patients with acute viral gastroenteritis, and four PCR products were randomly selected for further studies on sequencing. When comparing to the nucleotide sequences of norovirus reference strains from GenBank, the highest homology was found between the four isolates and the norovirus GII/4 strains. The four strains isolated from Beijing were almost identical to the GII/4 variants that causing epidemics in the Netherlands and in Japan with the homology of 97.8%-98.5% and 95.2%-95.9%, respectively. Phylogenetic analysis revealed that the four isolates were located at the same branch as the norovirus GII/4 variants in Netherlands and Japan.

CONCLUSIONNew norovirus GII/4 variants were found in Beijing, and data from sequence analysis showed that the four isolates and the epidemic strains isolated from both the Netherlands and Japan in 2006 belonged to the same group of norovirus GII/4.