Calpain-1: a Novel Antiviral Host Factor Identified in Porcine Small Intestinal Mucus
Yuchen Li, Xiuyu Wang, En Zhang, Ruiling Liu, Chengjie Yang, Ying Duan, Yuqi Jiang, Qian Yang
Abstract
Although the antiviral activity of the intestinal mucus was recognized 20 years ago, the antiviral active ingredients in the mucus are poorly understood. Currently, most research on antiviral molecules in the intestinal mucus remains limited to members of the mucin family. This study identified the cysteine protease calpain-1 as a novel antiviral protein in porcine small intestinal mucus and revealed its underlying protective mechanism for the first time. This mechanism involves inhibiting porcine epidemic diarrhea virus (PEDV) invasion by binding and hydrolyzing the S1 domain of the viral spike protein. Furthermore, the results of our PEDV-challenge experiment in piglets indicated that calpain-1 provides effective protection against intestinal PEDV infection. Our findings provide new insights into the protective function of the small intestinal mucus. In addition to potential therapeutic implications for the swine industry, our analysis of antiviral proteins in the small intestinal mucus may have implications for the prevention and control of coronavirus infection in humans.