TLR2 and pneumococcal meningitis: Previous analyses of mice lacking expression of single or multiple TLRs such as TLR2, -4, and/or -9 suggested involvement of all 3 in S. pneumoniae–induced immune cell activation in vitro as well as in pneumococcal pneumonia (11–13), but only of the first 2 in pneumococcal meningitis (14, 15).