The protective role of TLR2, TLR4, and TLR9 against pneumococcal infection is suggested by the results obtained from studies using either TLR2, TLR4, or TLR9 knockout or mutant mice (Branger et al., 2004; Knapp et al., 2004; Albiger et al., 2007) (Figure 3). The gene discussed is TLR4; the disease is pneumococcal infection.