Objective Characteristics and epidemiology of the muscovy duck white hepatitis in Fujian were studied, and genetic variations of the pathogen capsid protein determined.
Methods Clinical specimens of 9 suspected muscovy duck white hepatitis cases incurred at Fuzhou, Sanming, Putian, and Zhangzhou in the province were collected to test for DAdVs using pathogen detection methods. Isolated pathogens were identified, and their hemagglutination characteristics, pathogenicity, and hexon gene sequences determined.
Results The disease was found on muscovy ducks mostly in spring and autumn with an incidence rate of 15%–40% and a mortality rate of 5%–15%. The DAdVs were isolated and tested to be lethal to muscovy duck embryos. The infection rate of the virus on ducks ranged 60%–100% with a mortality rate of 20%–40%. The homology of the hexon gene nucleotides among the 9 isolated DAdVs was greater than 99.9%. The capsid proteins had sequences similar to that of CH-GD-12-2014 and were stable proteins without base deletion, insertion or recombination. The 9 isolates had a 99.9%–100% homology with CH-GD-12-2014 from Guangdong, 76.6%–76.7% with DAdV-GR from France, and 64.1%–66.8% with FAdV and other serotypes. They were in the same branch with GD-12-2014 and GR, but not AdV, on the phylogenetic tree.
Conclusion The strains of the muscovy duck adenovirus circulating in Fujian Province in 2022 belonged to the DAdV Type 2.