Epidemiological Investigation and Molecular Characterization of Chicken Infectious Anemia Virus in Broilers in Liaoning Province, China

Chicken anemia virus (CAV) targets the immune system of chickens, causing anemia and atrophy of the bone marrow and lymphoid organs, resulting in significant damage to poultry farming. From April 2024 to March 2025, a total of 359 liver samples were collected from broiler farms in 11 cities across Liaoning Province. CAV was detected using PCR, and 16 complete genome sequences of CAV isolates from different regions were analyzed through phylogenetic and recombination analyses. The overall CAV positivity rate was 13.9%, with spring identified as the peak season. Phylogenetic analysis and genotyping revealed that ten CAV strains clustered within subgroup C1, while the remaining six were distributed among subgroups C2 and C3, as well as Group D. Specific mutations were observed among the VP1 protein genotypes, including mutations previously associated with increased pathogenicity and transmission. One isolate, LN2511, was identified as a potential recombinant strain with its parents CAV-Shanxi7 and CAV-EG-13. During 2024-2025, CAV infection remained prevalent in Liaoning Province, with subtype C1 being the dominant genotype. Amino acid sequence analysis indicated the presence of highly pathogenic strains across the province. These findings fill a knowledge gap regarding CAV infection status and evolutionary trends in chicken populations in Liaoning, China.