Claudin-1 are exclusively located in the junctional area of IPEC-J2 cells following infection with a variety of porcine ETEC strains and porcine epidemic diarrhea virus [40, 41], indicating the essential role of this TJ protein in preventing intestinal pathogens to enter the paracellular space and invade the host [42]. This evidence concerns the gene CLDN1 and infection.