Genetic and Pathogenic Characterization of a Porcine Deltacoronavirus Strain Isolated in Zhejiang Province, China

Porcine deltacoronavirus (PDCoV) has emerged as a significant pathogen in swine, affecting animal health and posing potential risks for cross-species transmission. In this study, we successfully isolated a PDCoV strain named HZYH-2019 from the feces of diarrheal sows in Zhejiang Province, China. The viral growth curve demonstrated strong adaptation of this strain to cells, with particularly high replication efficiency observed in LLC-PK1 cells. Genomic analysis revealed a high degree of nucleotide sequence similarity between PDCoV HZYH-2019 and other PDCoV strains. A notable mutation at the tenth amino acid position of the spike protein altered the predicted signal peptide position. Phylogenetic analyses indicated that PDCoV HZYH-2019 clustered with Chinese strains, while four Chinese strains were grouped within the American spectrum, suggesting that the pork trade may facilitate cross-border virus transmission. Analysis of known PDCoV strains inferred that PDCoV may have originated in Asia and that there is cross-species transmission from birds to mammals. Notably, PDCoV HZYH-2019 caused diarrhea in piglets without mortality, although significant intestinal lesions were observed. These findings enhance our understanding of PDCoV's biological behavior and zoonotic potential, informing the development of effective vaccines and control measures to manage future outbreaks.