Figure 2.
Sialic acid content of the capsular polysaccharide (CP) conjugates is critical for induction of functional immune responses. CP was either partially desialylated (open circles) or nontreated (closed circles) prior to conjugation. Groups of 10–20 female CD-1 mice were vaccinated with 1 μg of CP monovalent CP-CRM197 conjugate at weeks 0, 3, and 6. Serotype-specific opsonophagocytic activity (OPA) titers were determined in serum samples obtained at week 8. Geometric means are shown as bars with 95% confidence intervals. The lower limit of OPA detection was 100. The dotted line denotes a titer of 50, which was assigned to results below the limit of detection. Significant decreases after desialylation are shown. *P < .05, **P < .01, ***P < .001, and ****P < .0001.