FIG. 2.

Binding of anti-PspA antibodies and complement deposition on the pneumococcal surface. Pooled sera from BALB/c WT and IL-4 KO mice immunized with a recombinant protein or DNA vaccine were tested for the abilities to bind to the pneumococcal surface (A) and to mediate C3 deposition (B). S. pneumoniae strain P-30 was incubated with 25% serum from mice immunized with DNA vaccine vector pSec-pspA3NS (solid lines)-, recombinant PspA3NS (dotted lines)-, or alum-immunized animals (gray areas). The median fluorescence of the bacteria is shown for each sample. Results are representative of two independent experiments.