[Study on norovirus GII.4/Sydney 2012 variant in China]

To study the nucleotide and amino acid sequences of norovirus G II.4/Sydney 2012 variants, in China.

Twenty-two stool specimens, confirmed as G II.4/Sydney 2012- positive were collected from Beijing in the winter of 2012-2013. RT-PCR was performed to target the complete capsid gene. G II.4/Sydney 2012 strains from other regions in China were searched and obtained from the GenBank. Nucleotide and amino acid sequences of G II.4/Sydney 2012 strains were analyzed, using the CLUSTAL X(Version 1.83)and followed by phylogenetic analysis using Mega version 5.1.

The complete major capsid nucleotide sequences of thirty-eight G II.4/ Sydney 2012 strains from seven regions in China were obtained. The VP1 nucleotide and amino acid sequences diversity were 0.1%-3.3% and 0-3.1%, respectively. Result from phylogenetic analysis demonstrated that the G II.4/Sydney 2012 variant shared a common ancestor with both the dominant norovirus G II.4 variants Apeldoorn 2008 and the New Orleans 2009. G II.4/Sydney 2012 variants appeared to have had two A/D/E site combinations at the amino acid level, TSRN-GTT-SNT and TSRN-STT-SNT.

G II.4/Sydney 2012 variant had been circulating in many regions in China. There seemed a high nucleotide and amino acid identity among G II.4/Sydney 2012 strains collected from China. G II.4/Sydney 2012 variants showed different A/D/E site combination from other pandemic G II.4 variants.