Epidemiological status and genome characteristics of canine parvovirus in China from 2022 to 2024

Canine parvovirus (CPV) is a highly contagious and lethal virus that primarily affects dogs. The virulence and transmissibility of this virus have intensified over time, posing significant challenges to the prevention and control of this pathogen. In this study, to investigate the epidemiology of CPV in China, 2,654 fecal samples were collected from seven provinces, and the positive rate was found to be 50.53%. The positive rates in Liaoning, Shandong, Hubei, Hunan, Guangxi, Jiangxi, and Fujian provinces were 78.53%, 9.25%, 58.37%, 3.00%, 42.68%, 78.26%, and 41.47%, respectively. Among these samples, four genotypes were identified: CPV-2 (4.42%), CPV-2c (69.04%), new CPV-2a (23.81%), and new CPV-2b (2.7%). Notably, CPV-2c emerged as the most prevalent genotype. Amino acid sequence alignments indicated that the main substitutions in VP2 were M87L, S297A, A300G, Y324I, N375D, and N426D/E, and the main substitutions in NS1 were I60V, Y544F, E545V, and L630P. Moreover, the mutations A5G, Q370R, and N426E were observed to be nearly universal among all CPV-2c strains, and I60V, Y544F, E545V were mainly found in CPV-2c and new CPV-2b strains. Phylogenetic analysis based on VP2 sequences revealed that CPV and FPV formed two distinct clusters. Furthermore, the CPV cluster was subdivided into four groups: CPV-2, CPV-2c, new CPV-2a, and new CPV-2b. However, the sub-branch of the NS1 evolutionary tree did not correspond strictly to the CPV genotype. In summary, our findings revealed significant variation in the prevalence of CPV across different regions in China. These findings carry significant implications for our understanding of CPV transmission dynamics and will play an important role in informing vaccine development strategies.