Molecular characterization of chicken anemia virus in Guangxi Province, southern China, from 2018 to 2020

BACKGROUND: Chicken anemia virus (CAV) causes chicken infectious anemia, which results in immunosuppression; the virus has spread widely in chicken flocks in China. OBJECTIVES: The aim of this study was to understand recent CAV genetic evolution in chicken flocks in Guangxi Province, southern China. METHODS: In total, 350 liver samples were collected from eight commercial broiler chicken farms in Guangxi Province in southern China from 2018 to 2020. CAV was detected by conventional PCR, and twenty CAV complete genomes were amplified and used for the phylogenetic analysis and recombination analysis. RESULTS: The overall CAV-positive rate was 17.1%. The genetic analysis revealed that 84 CAVs were distributed in groups A, B, C (subgroups C1-C3) and D. In total, 30 of 47 Chinese CAV sequences from 2005-2020 belong to subgroup C3, including 15 CAVs from this study. There were some specific mutation sites among the intergenotypes in the VP1 protein. The amino acids at position 394Q in the VP1 protein of 20 CAV strains were consistent with the characteristics of a highly pathogenic strain. GX1904B was a putative recombinant. CONCLUSIONS: Subgroup C3 was the dominant genotype in Guangxi Province from 2018–2020. The 20 CAV strains in this study might be virulent according to the amino acid residue analysis. These data help improve our understanding of the epidemiological trends of CAV in southern China.