CD274 and human granulocytic anaplasmosis: Our previous studies demonstrated that blockade of the PD-1/PD-L1 pathway and/or PGE2 effectively improved antigen-specific immune reactions in bovine chronic diseases, such as bovine leukemia virus infection, Johne's disease, and anaplasmosis (18–20, 23, 24, 60, 62, 63, 69).