3.7 Sequence analysis of VP7 segments deserved to G8 genotype
To better understand trends in the epidemiology of G8 strains, a representative number of samples were included in the sequence and phylogenetic analysis. In our study, 72 out of 92 strains were successfully sequenced and the VP7 sequence was 881 bp in length. According to the phylogenetic analyses, all 72 VP7 nucleotide sequences of G8 were clustered exclusively in lineage 1 of DS-1-like G8 strains previously isolated from several Asian regions (Figure 4). Further analysis showed that the VP7 nucleotide sequence similarities among themselves were 89.2%-100.0%. The Shanghai strains were most closely to the reference strains isolated from other Asian regions in nucleotide sequences identity (94.1% to 99.6%), while the nucleotide sequence similarity between the Shanghai strains and the references reported from other regions was relatively low with the nucleotide sequence identity being less than 90.0%. Of note, the nucleotide sequence identities between the Shanghai strains and bovine strains ranged from 72.9% to 96.2%, while the amino acid sequence among them showed 88.5%-96.8% sequence identity with each other.