Cross-Species Transmission and Recombination Between Feline and Canine Coronaviruses in Jiangsu-Zhejiang Region in 2025.

Feline and canine coronaviruses (FCoVs and CCoVs) are widely prevalent in companion animals. The recent emergence of a highly virulent FCoV-CCoV recombinant virus, FCoV-23, caused a rapid feline infectious peritonitis (FIP) outbreak in Cyprus, which raises a serious concern about the cross-species transmission of CoVs among companion animals. Here, we evaluated the prevalence, transmission and evolution of FCoV and CCoV in the Jiangsu and Zhejiang provinces of China in 2025. A universal RT-qPCR assay for FCoV and CCoV was established and used for the detection of 700 clinical samples, including 501 from cats and 199 from dogs. A total of 92 samples (13.14%, 92/700) were detected as positive, containing 79 positive samples (15.76%, 79/501) from cats and 13 positive samples (6.5%, 13/199) from dogs. Ten complete S genes and two complete genomes were obtained from positive samples. Fragment comparison and phylogenetic analysis identified one CCoV-I sequence from a feline sample and one FCoV-II sequence from a canine sample. Furthermore, recombination analyses not only detected intra-species recombination events but also inter-species cross-over events. Collectively, this study, for the first time, revealed that cross-species transmission and recombination events occurred between FCoV and CCoV among companion animals in the Jiangsu-Zhejiang region of China in 2025.