CD8A and infection: Experimental studies on rodents show that co-infection regulates the host’s immune response to A. phagocytophilum and the production of interleukins (ILs), and reduces IFN-γ Level and the number of CD8 + T cells, leading to more serious clinical symptoms, increasing the burden of pathogens in blood and tissues, and leading to long-lasting infections [40,41,42,43].