Since IFN-γ−/− or IFN-γR−/− mice are more susceptible to infection with African trypanosomes than wild-type mice (15, 16), it is conceivable that the early mortality of infected MyD88−/−, TLR9−/−, and IL-12p70−/− mice is attributed to, at least in part, the impaired capacity of synthesis of IFN-γ (25, 46). Here, TLR9 is linked to infection.