[Rotavirus G9-Ⅵ Re-emerging and Circulating Predominantly in Children with Diarrhea in Beijing]

The first reported group A rotavirus(RVA)G9 strain T203 in mainland China detected from an infant in Beijing in 1994 clustered within VP7 lineage Ⅵ(G9-Ⅵ),whereas the common RVA G9 belong to VP7 lineage Ⅲ(G9-Ⅲ) worldwide. Interestingly, since it was first reported in 1994 there was no G9-Ⅵ circulating in Beijing, until an unexpected G9-Ⅵ strain was identified by sequencing in 2010 RVA surveillance. This present study was to develop a convenient and effective dot-blot hybridization method for differentiating G9-Ⅲ and G9-Ⅵ rotaviruses, to investigate the re-emerging circulating distribution of G9-Ⅵ RVAs in outpatient children with diarrhea from 2011 to 2012in Beijing. By multiple-sequence aligning and analyzing the collected VP7 gene nucleotide sequences of G9 RVAs worldwide from GenBank database using Clustal W software, a region within VP7 gene which is highly divergent between G9-Ⅲ and G9-Ⅵ rotaviruses and conserved within themselves was selected as probe. One pair of common primers at both side of this probe region was designed, and used for synthesizing DIG labeled G9-Ⅲ and G9-Ⅵ probes with PCR, respectively. Subsequently, RVA G and P genotypes were identified as previously described. Then G9-Ⅲ and G9-Ⅵ were further differentiated from G9 RVAs using dot-blot hybridization method established in this study. It was showed that G9 was the most prevalent genotype(43.5%),followed by G3(30.5%)、G1(12.2%)and G2(11.5%),and no G4 genotype was detected.Interestingly,G9-Ⅵ was the most predominant(96.5%) type, while only 3.5% was G9-Ⅲ among these G9 rotaviruses.Phylogenetically,G9-Ⅵ rotaviruses in this study clustered closely with human G9-Ⅵ rotaviruses which were more recently re-emerging in several countries including China around the world as well as porcine G9-Ⅵ rotavirus strain F7P4 in Canada, whereas they clustered distantly to worldwide common G9-Ⅲ strains.G9-Ⅵ rotaviruses were re-emerging in the world, whether it gained stronger spreading ability or virulence than ever common G9-Ⅲ during evolution with porcine G9-Ⅵ rotaviruses need further analysis.