PEDV Structural Proteins with Emphasis on M Protein as an Immunomodulatory Factor in Porcine Innate Immunity

Porcine epidemic diarrhea virus (PEDV) is an enteric alphacoronavirus that causes severe diarrhea and high mortality in neonatal pigs, leading to substantial economic loss in the porcine industry. Previous studies have primarily focused on the spike protein because of its role in viral entry and induction of neutralizing antibody responses. However, accumulating evidence indicates that other viral components also contribute to host immune modulation and pathogenesis. This review summarizes the current knowledge on PEDV structural proteins, with an emphasis on membrane proteins as regulators of porcine innate immune responses. The molecular characteristics and intracellular localization of membrane proteins were described, and the reported effects on interferon signaling, inflammatory pathways, and cellular stress responses were examined. Findings from related coronaviruses were incorporated to highlight the conserved features and virus-specific differences in membrane protein-mediated host modulation. Available evidence suggests that membrane protein-associated interference with innate immune signaling may contribute to intestinal immune dysregulation and disease severity in neonatal piglets. The implications of these observations on PEDV pathogenesis and intervention strategies are also discussed. By shifting attention from spike-centered frameworks to structural protein-driven host interactions, this review highlights membrane proteins as an underexplored but biologically relevant factor in porcine coronavirus research.