FIG. 4.

Virus-specific antibody responses were detected in mucosal secretions. Anti-gp120 IgG specific activity (SA) was monitored longitudinally in CVS of immunized animals prior to infection (black), from the week each became infected (blue), and for the two that did not become infected (green) (A). Mucosal antibody responses in the naïve animals were measured prior to infection (gray) and postinfection (red). The 20-week challenge phase is shaded. The dashed line indicates the limit of detection, defined as the mean plus 3 standard deviations of negative samples. Anti-gp120 IgG SAs in CVS and plasma are correlated (Spearman's r = 0.91; P < 0.0001) (B). The ratios of anti-gp120 SA in CVS versus plasma were significantly higher at the five prechallenge time points in the two animals that remained SIV negative (C) (ratio, 3.6; 95% CI, 3.1 to 4.0; P < 0.001). IgG samples containing readings below the limit of detection, defined as 3 standard deviations above the average SA for naïve controls, were excluded from correlative and ratio analyses (B and C). IgA SA was monitored against gp120 in CVS (D) and rectal secretions (E) and against viral lysate in CVS (F) and rectal secretions (G).