Abstract
Canine coronavirus (CCoV) is a positive-strand RNA virus generally responsible for mild-to-severe gastroenteritis in dogs. In recent years, new CCoVs with acquired pathogenic characteristics have emerged, turning the spotlight on the evolutionary potential of CCoVs. To date, two genotypes are known, CCoV type I and CCoV type II, sharing up to 96% nucleotide identity in the genome but highly divergent in the spike gene. In 2009, the detection of a novel CCoV type II, which likely originated from a double recombination event with transmissible gastroenteritis virus (TGEV), led to the proposal of a new classification: CCoV type IIa, including classical CCoVs and CCoV type IIb, including TGEV-like CCoV. Recently, a virus strictly correlated to CCoV was isolated from children with pneumonia in Malaysia. The HuPn-2018 strain, classified as a novel canine-feline-like recombinant virus, is supposed to have jumped from dogs into people. A novel CoV of canine origin, HuCCoV_Z19Haiti, closely related to the Malaysian strain was also detected in a man with fever after travel to Haiti, suggesting that infection with Malaysian-like strains may occur. These data and the emergence of highly pathogenic CoVs in humans underscore the significant threat that CoV spillovers pose to humans and how we should mitigate this hazard.