Phylogenetic analysis
To investigate the evolutionary relationship of DAstV -SDZZ with other astroviruses for which corresponding sequences were available, phylogenetic trees were constructed based on nucleotide sequences of the ORF 1a, ORF 1b and ORF 2 homologous genome (Figure 2). All the three trees demonstrated that the DAstV -SDZZ isolate located on the identical branch as the other DAstV-1. The DAstV-1 strain was closely related to some turkey astroviruses in ORF 1a and ORF 2 genes, whereas DAstV-1 formed another clade with CAstV and DAstV CPH in the ORF2 region. Comparison of the other DAstV-1 strain with the deduced amino acid sequences of DAstV-SDZZ isolate were performed. As shown in Table 1, the deduced amino acid sequences of the DAstV-SDZZ with other DAstV-1 strain shared identities of 94.4% to 99% in ORF1a, 96.9% to 98.4% in ORF1b, and 95.5% to 99.9% in ORF2. The amino acid of capsid protein of the DAstV-SDZZ shared identities of 40.5% and 56–56.1% with TAstV-1 and GoAstV strains, respectively. These observations suggest that DAstV-SDZZ is an isolate of DAstV-1.