FIG 8.

Expression of key pneumococcal virulence factors determined by quantitative Western blot analysis. Expression levels of CbpA (A), NanA (B), and Ply (C) were compared for strain 4496 and the 4496ΔPPI1 mutant grown to mid-log phase in C+Y media using the relevant antisera. The size of the relevant protein is indicated. Data are means ± SEM (in fluorescence units) of the results of biological triplicates. Mean levels of expression were compared between strains for each target by unpaired two-tailed t tests (P < 0.05).