CD40 and infection: Considering the potential role of CD40 in IFN-I response and our observation of up-regulation of IFN-I and CD40 expression in P. yoelii nigeriensis N67 (N67) infection [8], we investigated the functional roles and the relationship of CD40 and STING in host response to N67 parasite infection and showed that the serum level of IFN-β was significantly reduced in CD40 knockout (KO) mice day 2 after N67 infection, leading to early host death.