Fig 5.
Opsonophagocytic assay. Pneumococcal strain 679/99 (PspA clade 3, serotype 6B, used to test the opsonic activity of anti-PS6B antibodies [Ab]) (A) and pneumococcal strain 245/00 (PspA clade 1, serotype 14, used to test the opsonic activity of anti-PspA1 antibodies) (B) were incubated with the sera from mice immunized with PS6B-rPspA1 or with PS6B-OCT-mPspA1 and a complement source. The opsonized pneumococci were incubated with peritoneal cells and plated on blood agar plates. Sera from mice immunized with saline plus Al(OH)3 or with PS6B coadministered with rPspA1 or mPspA1 were used as controls. The numbers of CFU recovered after 20 h were compared by one-way ANOVA with Tukey's multiple-comparison test. The lines on the graph represent means. Asterisks indicate statistically significant differences (**, P < 0.001; ***, P < 0.0001). ns, nonsignificant differences.