Tight junction protein claudin-1 is a novel internalization factor for swine enteric coronaviruses infection

We observed a downregulation in the expression of the majority of tight junction proteins in intestinal tissues infected with transmissible gastroenteritis virus (TGEV). However, unexpectedly, claudin-1 exhibited a significant upregulation in intestinal epithelial cells. This intriguing finding prompted us to delve deeper into the potential role of claudin-1 in facilitating virus invasion of epithelial cells. Utilizing overexpression and knockout cell lines, we demonstrate that claudin-1 is an internalization factor for swine enteric coronaviruses (SeCoVs), including TGEV, porcine epidemic diarrhea virus (PEDV), and porcine deltacoronavirus (PDCoV). Notably, claudin-1 interacts with the S1 protein of TGEV, PEDV, PDCoV, and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), spanning across alpha, beta, and delta coronaviruses. Our findings provide deeper insights into the infection mechanisms and pathogenesis of SeCoVs and SARS-CoV-2.