Origin, Evolution, and Virulence of Porcine Deltacoronaviruses in the United States

Ma, Yuanmei; Zhang, Yu; Liang, Xueya; Lou, Fangfei; Oglesbee, Michael; Krakowka, Steven; Li, Jianrong

Aside from genomic sequence data, nothing is known about the U.S. PdCV. Although the virus is identified in diarrhea outbreaks, experimental studies that directly demonstrate its diseasecausing potential remain to be shown. The objective of this study is to characterize the U.S. PdCV isolate in terms of genetic characteristics, phylogeny, and virulence in gnotobiotic (Gn) and con-ventional piglets. Genomic sequencing found that U.S. PdCV strains share 99.6 to 99.7% homology with each other and 99.0 to 99.1% homology with Hong Kong isolates (HKU15-155 and HKU15-44). We found that the U.S. PdCV strains caused severe diarrhea, vomiting, and dehydration clinically indistinguishable from those caused by PEDV and TGEV. Histologically, the PdCV strains caused severe lesions in the stomach and small intestine and mild interstitial pneumonia in lungs. Collectively, our study provides the first proof that PdCV causes significant enteric disease in swine.