Analysis on VP7 and VP4 genes of human rotavirus G9 identified from children with diarrhea in Beijing, from 2007 to 2008

Abstract

To characterize the outer capsid protein VP7 and VP4 encoding genes of human rotavirus G9 strains detected in Beijing, from 2007 to 2008. Full length of VP7 genes of G9 rotaviruses from 12 fecal specimens previously detected by dot-blot hybridization assay were amplified by RT-PCR and sequenced after being cloned into T vector. The sequences of these VP7s were compared to VP7 genes of rotavirus G9 prototype strains and recently circulating strains around the world. VP4 genes of these 12 G9 strains were amplified by nested-PCR for P genotyping. Sequence analysis for the full length of VP7 genes from these 12 specimens confirmed that they were G9 rotaviruses. P genotyping for VP4 genes revealed that both P[8]G9 and P[6]G9 were circulating in Beijing in the last 2 years. Sequence and phylogenetic analysis demonstrated that VP7 genes of G9 strains from Beijing in this study were clustered in the lineage III which resembled the G9 strains circulating in other places around the world, indicated by high identities of nucleotide and deduced amino acid sequences and were distant with the first reported G9 strain T203 identified in China in 1994. It was found that there were some consistent amino acid substitutes at the corresponding positions among VP7s from these 12 specimens and from Xinjiang and Wuhan, both in G9P[8] and G9P[6] strains. The rotavirus G9 strains both in combination of G9P[8] and G9P[6] were circulating in Beijing in the past years. It seemed that rotavirus G9 should be included in the list of surveillance for rotavirus in China.