A virulent infectious bronchitis virus (IBV), designated as CK/CH/GD/QY16 (referred as QY16), was isolated from a diseased chicken farm in Guangdong province, China, in 2016. The complete genome of the strain was sequenced and analyzed. The results show that the genome of QY16 consists of 27,670 nucleotides, excluding poly (A) tail, and that its genome organization is 5' UTR-1a-1b-S-3a-3b-E-M-4b-4c-5a-5b-N-6b-3' UTR-poly (A) tail. Sequence comparison among QY16 and other IBV strains was conducted and its results demonstrate that the S1 gene of QY16 has the highest nucleotide sequence identity with that of 4/91, and the other part of its genome is highly similar to that of YX10. The results of the phylogenic analysis show that the entire genome of QY16 and most of the QY16 genes are located in the same cluster as those of YX10, except for the S1 gene which is located in the same cluster with that of 4/91. It has been further confirmed by the RDP and SimPlot analysis that QY16 is a recombinant strain deriving from YX10 (as the major parental sequence) and 4/91 (as the minor parental sequence), and that the recombination occurs in a region which includes the 3'-terminal 1b sequence (85 nt) and the 5'-terminal S1 protein gene sequence (1,466 nt). The results of the vaccination-challenge test suggest that QY16 is a nephropathogenic strain of IBV and that the vaccine strains-H120 and 4/91-cannot provide effective protection against it. These results indicate that the continuing evolution of IBV strains by genetic drift and genetic recombination may lead to IBV outbreaks even among the vaccinated chickens 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.
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