Porcine epidemic diarrhea virus (PEDV) is an enteric coronavirus that causes high mortality in piglets, thus posing a serious threat to the world pig industry. Porcine epidemic diarrhea (PED) is related to the imbalance of sodium absorption by small intestinal epithelial cells; however, the etiology of sodium imbalanced diarrhea caused by PEDV remains unclear. Herein, we first proved that PEDV can cause a significant decrease in Na+/H+ exchanger 3 (NHE3) expression on the cell membrane, in a viral dose-dependent manner. Further study showed that the PEDV nucleocapsid (N) protein participates in the regulation of NHE3 activity through interacting with Ezrin. Flame atomic absorption spectroscopy results indicated a serious imbalance in Na+ concentration inside and outside cells following overexpression of PEDV N. Meanwhile, molecular docking technology identified that the small molecule drug Pemetrexed acts on the PEDV N-Ezrin interaction region. It was confirmed that Pemetrexed can alleviate the imbalanced Na+ concentration in IPEC-J2 cells and the diarrhea symptoms of Rongchang pigs caused by PEDV infection. Overall, our data suggest that the interaction between PEDV N and Ezrin reduces the level of phosphorylated Ezrin, resulting in a decrease in the amount of NHE3 protein on the cell membrane. This leads to an imbalance of intracellular and extracellular Na+, which causes diarrhea symptoms in piglets. Pemetrexed is effective in relieving diarrhea caused by PEDV. Our results provide a reference to screen for anti-PEDV targets and to develop drugs to prevent PED.IMPORTANCEPorcine epidemic diarrhea (PED) has caused significant economic losses to the pig industry since its initial outbreak, and the pathogenic mechanism of porcine epidemic diarrhea virus (PEDV) is still under investigation. Herein, we found that the PEDV nucleocapsid protein interacts with Ezrin to regulate Na+/H+ exchanger 3 activity. In addition, we screened out Pemetrexed, a small molecule drug, which can effectively alleviate pig diarrhea caused by PEDV. These results provide support for further exploration of the pathogenesis of PEDV and the development of drugs to prevent PED.
Keywords: Ezrin; Pemetrexed; nucleocapsid protein; piglet diarrhea; porcine epidemic diarrhea virus.