First Identification and Phylogenetic Analysis of Porcine Circovirus Type 4 in Fur Animals in Hebei, China

SIMPLE SUMMARY: Hebei Province is an important animal husbandry region in China, especially in the fur animal farming industry. Because of poor feeding condition, fur animal farms often suffer cross-species pathogens from the surrounding pig farms. In 2019, a novel porcine circovirus, designated porcine circovirus type 4 (PCV4), was first detected in Hunan province. Therefore, a retrospective epidemiological study on PCV4-infected fur animals was performed in the frozen specimens of pigs and fur animals collected from 2015 to 2020. The results showed that PCV4 has been widely spread among pigs and fur animals in Hebei Province, China. To sum up, this is the first study to detect PCV4 in fur animals. Our findings also provide new evidence for PCV4 cross-species transmission and strengthen the hypothesis that PCV4 cross-species transmission will be a serious threat to the fur animal farming industry. ABSTRACT: A novel circovirus called porcine circovirus type 4 (PCV4) was recently detected in pigs suffering from severe clinical diseases in Hunan province, China. There are few reports on the origin and evolution of PCV4, although some researchers have conducted epidemiological investigations of PCV4 and found that PCV4 is widespread in pigs. Based on the previous study, we detected PCV2 in farmed foxes and raccoon dogs with reproductive failure. To explore whether the PCV4 genome also exists in fur animals, we detected 137 cases admitted from fur animal farms in Hebei China between 2015 and 2020, which were characterized by inappetence, lethargy, depression, abortion, and sterility. The overall infection rate of PCV4 was 23.36% (32/137), including 20.37% (22/108) for raccoon dogs, 18.75% (3/16) for foxes, and 53.85% (7/13) for minks. Finally, five raccoon dog-origin PCV4 strains and one fox-origin PCV4 strain were sequenced in our study, whose nucleotide identities with other representative PCV4 strains varied from 96.5% to 100%. Phylogenetic analysis based on the complete genomes of PCV4 strains indicated a close relationship with those of PCV4 strains identified from pigs. To our knowledge, this is the first study to detect PCV4 in fur animals. Interestingly, we also identified PCV4 in a mixed farm (feeding pigs and raccoon dogs at the same time). In summary, our findings extend the understanding of the molecular epidemiology of PCV4 and provide new evidence for its cross-species transmission.