FIG 4.

The deficiency of either PspA or PspC enhances C3b deposition on the surface of S. pneumoniae. C3b deposition was detected by anti-human C3c antibody. The absence of C4b deposition on D39 does not lead to completely defective C3 opsonization of the pneumococcal surface. However, higher levels of C3b deposition were detected on PspA^–, PspC^–, and PspA^–/C^– strains, where C4b can also be detected. The results are expressed as means ± the SEM, representing three different experiments. P < 0.001 for all Psp mutant versus D39 comparisons (two-way ANOVA with Dunnett’s correction for multiple comparisons; results obtained with mannan were excluded from the analysis).