Canine circovirus (CanineCV) is a single-stranded DNA virus that circulates in dogs and wild carnivores around the world. It has been suggested to be associated with diseases of respiratory and gastrointestinal systems, though its pathogenic potential remains unclear. Currently, CanineCV is divided into six genotypes (genotype 1-6), and genotypes 2, 3, and 4 have been described in China. In this study, 359 blood samples from pet dogs with or without clinical signs were collected in Harbin city. After PCR screening, a total of 34 samples were tested positive for CanineCV, and nine full-length genome sequences were recovered from positive samples. Pairwise sequence comparison showed that they shared 82.4-99.3% genome-wide identity with other CanineCVs available in GenBank. Additionally, recombination events were detected, all of which were determined to be associated with sequences obtained in China. The reconstructed phylogenetic tree based on the recombination-free complete genome sequences revealed that the complete genome sequences generated herein were clustered into genotypes 1 and 3. Furthermore, purifying selection was the dominant evolutionary pressure acting on the genomes of CanineCV. These results expand the knowledge about the genetic diversity of CanineCV circulating in China, and also promote us to better understand the evolution of CanineCV.
Keywords: Canine circovirus; Genetic diversity; Pet dogs; Purifying selection; Recombination.
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