Novel genotyping and genetic heterogeneity of chicken parvovirus in central and Eastern China

Chicken parvovirus (CKPV) is frequently associated with avian intestinal diseases, posing a substantial threat to chicken industry. In this investigation, CKPV screening was conducted on 51 chicken farms from central and eastern China between 2022 and 2025. Finally, a total of 18 CKPV strains were identified and subjected to complete genome sequencing. Sequence similarity analysis showed that the 18 strains (93.46 %-97.68 %) were more similar to each other than to previously reported reference strains (40.40 %-95.97 %). To establish a novel genotyping system for CKPV, a p-distance frequency distribution and a neighbor-joining evolution tree based on VP2 amino acid sequences were constructed. CKPV was classified into two major genotypes, CKPV-1 (CKPV-1a/b) and CKPV-2 (CKPV-2a/b/c). All newly obtained CKPVs were clustered within the CKPV-1a subtype, along with reference strains from Brazil, Hungary, New Zealand, South Korea, Turkey, and the United States. In contrast, previously reported CKPVs from Guangxi Province, China, were distributed across multiple subtypes. Recombination analysis suggested four recombinant strains (AH231127, HB231019, HN230505, and HN231202), whose recombinant parental strains mainly originated from China and the United States. Amino acid analysis revealed hypervariable regions in the VP1 (residues 250-267 and 611-667), VP2, and NS1 (regions 319-334 and 637-647) proteins. Moreover, 22 amino acid substitutions were identified within predicted B-cell epitope regions of the capsid proteins. These results suggested the existence of both complex mutation patterns and recombination among circulating CKPV strains. This study aims to advance our understanding of CKPVs' molecular epidemiology and genetic evolution, contributing to a better understanding of its potential role in avian intestinal disease pathogenesis.