Emergence and Pathogenicity of a Novel Goose Adenovirus Type 4 Strain JA2485: Insights for Poultry Disease Control

In recent years, the prevalence and variation of goose adenoviruses, especially Goose Adenovirus Type 4 (GoAdV-4), have threatened waterfowl farming, while their genetic evolution and pathogenic mechanisms remain unelucidated. In May 2024, a novel GoAdV-4 strain (JA2485) was isolated from diseased Sanhua geese in Jian City, Jiangxi Province, China. It propagated in 11-13-day-old goose embryos, with a 50% embryo infectious dose (EID₅₀) of 10^2.2/0.1 mL. Whole-genome sequencing (GenBank Accession No. PQ152938) showed its genome is 43,030 base pairs long, containing 33 protein-coding regions and 2 fiber genes. Phylogenetic analysis revealed JA2485 is closely related to the Hungarian P29 strain and Chinese CH-FJZZ-202201 strain (nucleotide similarity: 94-96.8%), but clusters in a different branch from other avian adenoviruses. In pathogenicity tests on 1-day-old Sanhua geese, both subcutaneous injection and oral inoculation groups had 50% mortality. Infected geese showed weight loss, depression, reduced appetite, increased recumbency, and even paralysis in severe cases. Post mortem examination revealed hepatic rounded margins, yellowing, focal hemorrhages, and renal hemorrhagic lesions. Notably, viral loads were highest in the liver, duodenum, and cloacal swabs, suggesting fecal transmission. This study provides a key basis for clarifying GoAdV-4's evolutionary characteristics and pathogenic mechanisms, and formulating targeted prevention strategies.