Researchers of Hokkaido University, the National Agriculture and Food Research Organization (NARO), and Tohoku University demonstrated that a physiologically active substance called prostaglandin E2 (PGE2) impairs the immune response by upregulating the expression of an immunoinhibitory molecule, programmed death-ligand 1 (PD-L1), in cattle affected with Johne’s disease. The discovery is expected to help develop a