FIG. 4.
Correlation of functional antibody activity as measured by the weighted average of the percent inhibition of adherence and ELISA concentration of anti-PsaA IgG antibodies naturally found in human donor sera (n = 22). A weighted average of the percent inhibition of adherence observed with a given serum sample was calculated by using the log10 of each serum dilution factor as the weight. Analysis by the Pearson product moment correlation coefficient yielded a significant (P < 0.05) level of correlation (r = 0.73) between the calculated weighted average of the percent inhibition and the measured anti-PsaA IgG concentration of the human serum. Inhibition assays were performed with either Pnc serotype 18C or 19F.