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Since the first report from Cherry Valley ducks on a commercial duck farm in China (2008), duck astrovirus type 1(DAstV‐1)‐associated duck viral hepatitis (DVH) have been detected in several commercial duck flocks. A highly acute disease characterized by hepatitis broke out in ducklings in Shandong Province in March 2021, all diseased ducks have been immunized against the duck viral hepatitis vaccine. One DAstV‐1 strain, designated as DAstV‐SDWF, was isolated from a diseased duckling. Here, the isolation, cultivation, and characterization of DAstV‐1 isolate are described. The isolated astrovirus grew well in the LMH cell line. To determine the entire genomic of the DAstV‐SDWF isolate, the next‐generation sequencing (NGS) technique was conducted on the Illumina HiSeq platform. Complete genome sequence analysis revealed that DAstV‐SDWF isolate was 91.6%–98.6% homology with others DAstV‐1 deposited in Genbank. Similar clinical symptoms were successfully reproduced by an experimental infection study using the DAstV‐SDWF isolate. DAstV‐SDWF is the first DAstV‐1 strain whose experimental infection study has been conducted in China. Results of the above data demonstrated that DAstV‐1 could be one of the causative agents of the DVH occurring in China. The present works are likely to provide new insights into the pathogenicity and evolution of DAstV‐1 in ducks. [ABSTRACT FROM AUTHOR]

Since 2013, there have been an increasing number of cases of arthritis in broilers caused by avian orthoreovirus (ARV) in China, and the virus remains highly virulent in chicks with high‐level maternal antibodies. However, little information is available about the complete gene analysis and pathogenicity of the epidemic ARVs. In the study, the ARV strain (V‐ARV‐SD26) was isolated from broilers associated with arthritis in Shandong Province. To genetically characterize the ARV strain, the whole‐genome sequencing was conducted by next‐generation sequencing (NGS) technique. Sequence analysis demonstrated that V‐ARV‐SD26 might have acquired its current genomic composition through several homologous and, in case of the λC, μA and σB, divergent reassortment events. To further investigate the pathogenicity of the strain, 160 one‐day‐old Ross broilers with maternal antibodies were equally divided into four groups (foodpad‐, eye mucosa‐ and intramuscular‐inoculated groups and the negative control group), three experimental groups were inoculated separately with the low‐dose virus fluid, and the negative control was equally inoculated with sterile PBS. The results showed that the symptoms of broilers in foodpad inoculation group were the most serious, while that of the eye mucosa infection group were the mildest. Meanwhile, the cloacal cotton swabs and organs were collected for qRT‐PCR detection to evaluate the infection status. In conclusion, these findings indicate that V‐ARV‐SD26 is a divergent ARV strain, which provide experimental data for the prevention and control of newly emerged reovirus, and have a certain reference value for the preparation and evaluation of new vaccines. [ABSTRACT FROM AUTHOR]

Since December 2017, an infectious disease has caused economic hardship for duck farms and breeding ducks in many regions of China. This disease characterized by spleen necrosis and swelling, is due to a variant strain of duck orthoreovirus (DRV) (Duck/N‐DRV‐XT18/China/2018), which we isolated from the spleen of diseased ducks. After isolating the virus, we used next‐generation sequencing technology to determine the entire genomic of the virus. Our phylogenetic analysis of 10 genomic segments showed that the N‐DRV‐XT18 strain is closely related to orthoreovirus isolates derived from ducks and geese, with nucleotide sequence identities for 10 genomic fragments ranging between 49.8% and 99.3%. In contract, the nucleotide sequence of N‐DRV‐XT18 genomic fragments are only 38.6% to 78.8% similar to the chicken orthoreovirus isolate. Therefore, we determined that this pathogen, causing duck spleen necrosis, is a new variant of a duck orthoreovirus that is significantly different from any previously reported waterfowl‐derived othoreovirus. [ABSTRACT FROM AUTHOR]