Isolation and identification of a highly pathogenic strain of porcine epidemic diarrhea virus

Porcine epidemic diarrhea virus (PEDV) causes acute watery diarrhea and high mortality in neonatal piglets, resulting in substantial economic losses to the global swine industry. Here, we successfully isolated a PEDV strain, designated CHN-CQ-2021, from PEDV-positive diarrheic samples collected from a pig farm in Chongqing, China. Electron microscopy observation revealed that the CHN-CQ-2021 strain exhibited typical coronavirus morphology and could be recognized by PEDV-specific antibodies. Phylogenetic analysis of its full-length genome and S gene further classified this isolate as a G2b variant strain. Importantly, 1-day-old newborn piglets were orally challenged with CHN-CQ-2021 at 2 × 106 50% tissue culture infectious dose/mL. Compared with the control group, the infected piglets developed severe diarrhea with 100% mortality. In addition, viral RNA was detected in rectal swabs and multiple tissues, including the intestinal tract and brain, with macroscopic/microscopic intestinal lesions and viral antigen distribution confirmed using histopathology and immunohistochemistry. These findings demonstrate the presence of a pathogenic PEDV strain in Chongqing, China, capable of causing severe neonatal piglets’ enteric disease.