The Gyrovirus genus consists of nonenveloped, icosahedral viruses with small circular single-stranded DNA genomes. Gyroviruses have been detected in diverse hosts, including humans, chickens, rodents, and cats. Two Gyroviruses were detected in canine serum samples using PCR in this study. The results indicated that four serum samples were positive for CAV (0.28%, 2/700) or AGV2 (0.28%, 2/700). Additionally, recombination analysis showed that AGV2 and CAV might have originated from the recombination of viruses similar to those detected in chickens and humans. We detected a total of 14 mutations in CAV VP1 amino acid sequences and identified new mutations at positions 31, 388, 390, 399, and 421 for the first time. The identification of T390C, C912T, T1230C, and T1297C mutations in AGV2 VP1, R93C mutations in AGV2 VP2, and R58C mutations AGV2 VP3 indicated that the differences might be related to a transboundary movement among hosts, which requires further elucidation. To the best of our knowledge, this study is the first report of an AGV2-infected dog in China, suggesting that the cross-species transmission of viruses with circular single-stranded DNA genomes is a public health concern.

Porcine circovirus type 1 (PCV1) was discovered in 1974 as a contaminant of a porcine kidney (PK-15) cell line and was generally accepted to be nonpathogenic. But recently it was shown to cause lesions in experimentally infected pig fetuses. Serological evidence and genetic studies suggested that PCV1 was widespread in domestic pigs. Thus, the molecular epidemiology and genetic variation of PCV1 are still necessary to understand. Here 247 tissue samples were collected from piglets in Guangxi Province, China and performed whole-genome sequencing of the PCV1 genome. Thirteen PCV1 strains were sequenced from the samples. Similarity analysis showed that there were 97.8% to 99.6% nucleotide similarity to each other and 97.1% to 99.8% nucleotide similarity to the 40 reference strains. Besides, based on sequence analysis, we found one putative recombinant virus named GXdx84 strain contained the open-reading frame 1 (ORF1) of PCV1 and the ORF2 of PCV2d-2, which was consistent with the results of phylogenetic analysis that compared PCV1 and PCV2 strains. Variation analysis of the amino acids of the capsid protein revealed that the GXyl224 strain, which encoded 235 amino acids, had two amino acids more than other strains. This is the first study to report that a cap gene mutation resulted in lengthening of in the gene sequence. These data contribute to the understanding of PCV1 evolution and molecular epidemiology that will facilitate programs for its control and prevention.

Background: Canine circovirus (CanineCV), a non-enveloped virus with a circular DNA genome, has been identified in various avian and mammalian species, including domestic and wild canids. This study aimed to comprehensively analyze the prevalence of CanineCV across diverse animal species in 11 provinces of China. Results: A total of 1,666 serum samples were collected, revealing a 5.82% prevalence of CanineCV in dogs, with the highest rates being observed in southern and eastern China. Phylogenetic analysis of 266 global CanineCV genomes sourced from the NCBI identified six distinct genotypes, elucidating the complex dynamics of their evolution. Evidence suggested a potential bat origin for CanineCV, with positive selection and high rates of evolution being observed. Recombination analysis revealed dynamic genetic exchange, highlighting the intricate nature of CanineCV evolution. Mutational analysis identified key amino acid substitutions likely to influence the virus’s adaptation. Additionally, glycosylation, palmitoylation, and SUMOylation sites were predicted, shedding light on crucial functional properties of the virus. Conclusions: This study provides a global perspective on the origin, genetic diversity, and evolutionary dynamics of CanineCV. Understanding these factors is crucial for elucidating its epidemiology and potential health risks.