Complete genome sequence and phylogenetic analysis of novel avastroviruses circulating in China from 2016 to 2018.

Avastrovirus-specific antibodies are widely detected in chickens in China. However, there are currently no commercially available vaccines for this group of viruses. To address this issue, we collected 76 tissue samples from Avastrovirus (AAstVs) antibody-positive chickens from farms across eight provinces in China from 2016 to 2018. The samples were then screened for the presence of AAstVs sequences by polymerase chain reaction analysis and a phylogenetic tree was constructed. Specific primers were designed to amplify the whole genome sequences of the viruses from four positive samples, with the genetic characteristics and structures of the resulting genomes then analyzed further. Overall, 42 (55.3 %) of the 76 samples were positive for AAstVs RNA. Phylogenetic analysis along with the ORF1b gene showed that 15 isolates were grouped in AAstV-1 and 27 of them were grouped in AAstV-2. None of the isolates was belonged to AAstV-3. Sequencing and structural analyses revealed that the genomes of the four isolates showed the typical characteristics of AAstVs genomes but were genetically distinct from other AAstVs. The results of this study will contribute to our understanding of the genetic characteristics of AAstVs in China.