Abstract
IMPORTANCE: Through the epidemiological survey of fowl adenovirus serotype 4 (FAdV-4) in poultry and wild birds in Yunnan Province from 2017 to 2021, this study provides a scientific basis for the prevention and control of FAdV-4 in the region. Currently, there is a lack of monitoring and epidemiological research on FAdV-4 in wild birds in China, offering valuable insights for future studies on the virus in wild populations. Additionally, the analysis of the fiber gene sequence of FAdV-4 identified the prevalent strains in Yunnan Province, which lays the groundwork for future treatment and prevention strategies. OBJECTIVE: This study aimed to understand the epidemic situation of FAdV-4 in Yunnan Province and provide a reference for the prevention and control of the infection. METHODS: Suspected samples of FAdV-4 were collected with the wild birds from overwintering habitat and naturally dying poultry from poultry farms in Yunnan Province, and polymerase chain reaction (PCR) detection of FAdV-4 and related co-infection pathogens, pathogen isolation, and genetic evolution analysis of the fiber gene were carried out. RESULTS: The results showed that the FAdV-4 positive rate in poultry and migratory birds was 11.3% and 0.3%, respectively. The infection rate of the poultry tissue samples was high in central and western Yunnan Province. The detection of common poultry infectious diseases prone to co-infection, it was found that the birds were mainly co-infected with pathogens such as infectious laryngotracheitis, chicken infectious anemia virus, and avian influenza virus. Five poultry-source strains and one wild bird-source strain were isolated, and phylogenetic analysis showed that they all had high homology with the early Chinese highly pathogenic strains and clustered with the same genetic and evolutionary clade as the Chinese reference strain. The fiber protein is characterized by loci that indicate highly pathogenic strains (G219D, P307A, V319I, and A308T). CONCLUSIONS AND RELEVANCE: The results of our study demonstrate that FAdV-4 continues to exhibit a high prevalence rate among poultry populations in Yunnan Province, China. Notably, we report the first detection of FAdV-4 in the feces of black-necked cranes.