Objective To investigate the epidemiological characteristics of chicken anemia virus (CIAV) in yellow-feathered broiler breeders in Guangdong, thereby providing a scientific basis for regional CIAV prevention and control strategies.

Method From March 2024 to January 2025, a total of 787 serum samples and 180 tissue samples (liver and spleen) were collected from six large-scale, unvaccinated yellow-feathered broiler breeder farms in Guangdong. Serum samples were obtained from parent flocks, while tissue samples were collected from deceased chicks under three weeks of age. Serum antibody detection, virus isolation, and whole-genome sequencing were then employed to investigate the prevalence and molecular characteristics of CIAV in these flocks.

Result Serum antibody ELISA revealed varying degrees of CIAV infection across all six flocks, with an overall antibody-positive rate of 50.8% (400/787). Farm-level positive rates ranged from 32.0% to 77.8%, and increased significantly with age, rising from 27.0% in flocks younger than 7 weeks to 89.6% in those aged 46–57 weeks. PCR testing of tissue samples from deceased chicks yielded a positive rate of 55.6% (100/180). Using MDCC-MSB1 cells, 11 CIAV strains were successfully isolated from the positive tissue samples. Whole-genome sequencing revealed that all 11 CIAV isolates had a genome length of 2 298 bp, with no base deletions or insertions. Nucleotide sequence similarity among the isolates ranged from 97.6% to 99.9%. Phylogenetic analysis classified 10 isolates as genotype IIIa and one isolate (GD24QY8) as genotype IIIb. All isolates possessed the 394Q amino acid residue, a molecular marker associated with highly pathogenic CIAV strains.

Conclusion CIAV infection is widespread in Guangdong’s yellow-feathered broiler breeder population, with the predominant strains being genotype IIIa that possess molecular markers of high pathogenicity. These findings underscore the need for enhanced surveillance and implementation of effective control measures against CIAV.