CASP1 and pneumococcal meningitis: To investigate whether S. pneumoniae activates caspase-1 and matures caspase-1-dependent cytokines in S. pneumoniae-infected mice, pneumococcal meningitis was induced by intracerebral injection of a bacterial suspension containing 106 CFU/ml of S. pneumoniae D39, D39ΔPLY or TIGR4 supplemented with or without recombinant PLY protein into the lateral ventricle.