Emergence and Genetic Analysis of Avian Gyrovirus 2 Variants-Related Gyrovirus in Farmed King-ratsnakes (Elaphe carinata): the First Report in China

Abstract

Avian gyrovirus 2 (AGV2), which is similar to chicken infectious anemia virus, is a new member of the Circovirus genus. AGV2 has been detected not only in chicken but also in human tissues and feces. In this study, a total of 91 samples (8 liver tissues and 83 faecal samples) collected from king-ratsnakes (Elaphe carinata) at 7 separate farms in Hubei and Henan, China, were analyzed to detect AGV2 DNA via specific PCR. The results indicated a low positive rate of AGV2 (6.59%, 6/91) in the studied animals, and all of the positive samples were from the same farm. The AGV2 strain HB2018S1 was sequenced, and the genome with a total length of 2376 nt contained three partially overlapping open reading frames: VP1, VP2, and VP3. Phylogenetic tree analysis revealed that the HB2018S1, NX1506-1 strain from chickens in China belong to the same clade, with nucleotide homology as high as 99.5%. In total, 10 amino acid mutation sites, including 44R/K, 74T/A, 256 C/R, 279L/Q, and 373V/A in AGV2 VP1; 60I/T, 125T/I, 213D/N, and 215L/S in AGV2 VP2; and 83H/Y in AGV2 VP3, were found in the genome of HB2018S1 that were different from those observed in most reference strains, suggesting that the differences are related to an transboundary movement among hosts which needs to be further elucidated. IMPORTANCE Recently, AGV2 has been detected in live poultry markets and human blood in mainland China. Previous findings indicated future studies should investigate the large geographic distribution of AGV2 and monitor the variants, the host range, and the associated diseases. To the best of our knowledge, this study is the first report on AGV2 infected poikilotherm, suggested that cross-host transmission of viruses with circular single-stranded DNA genomes would be a public health concern.