Isolation and genetic characterization of a novel adeno-associated virus from Muscovy ducks in China

Adeno-associated virus (AAV; genus Dependoparvovirus, family Parvoviridae) was first discovered in 1965 as a contaminant in adenovirus preparations. The AAVs are generally considered non-pathogenic, and they have the ability to attenuate the replication of other more pathogenic viruses, which makes them attractive as potential therapeutics or preventative measures. This study characterized a novel AAV isolated from Muscovy ducks in China. The novel virus (MHH-05-2015) was isolated after propagating a field isolate of the DAdV-3 virus (a type 3 duck adenovirus) in duck embryo fibroblasts. The full genome sequence of MHH-05-2015 was determined, and the nucleotide and amino acid sequences were compared to other avian AAVs. The genomic distribution of the structural and non-structural protein-coding genes in MHH-05-2015 was conserved and consistent with the other AAVs. Compared to previously isolated avian AAVs, MHH-05-2015 had approximately 63 to 64% sequence identity. Phylogenetic analysis indicated that MHH-05-2015 clustered separately from other avian AAVs, suggesting that MHH-05-2015 was not directly descended from other Dependoparvovirus family members. These results suggest that MHH-05-2015 is a new subtype of AAV that is distinct from other avian AAVs.