TLR2 and infection: This has been shown in mice (Myd88-/- [50] and Tlr2-/- [51] mice have significant immune and host defense defects) as well as in humans (TLR2 expression [52] and a Tlr1 polymorphism [7] are associated with altered immune response to B. burgdorferi OspA vaccination and B. burgdorferi RST1 infection, respectively).