Figure 3.

Anti-V3 crown plasma Ab responses in VAX003 and VAX004 vaccine recipients over 7 immunization doses. ELISA reactivity of plasma IgG from 23 VAX003 and 23 VAX004 vaccinees was assessed against linear V3 crown peptide, cyclic V3 cradle peptide, and cyclic V3 ladle peptide. All peptides were biotinylated. Plasma was tested at prebleed (A02) and 2 weeks after each AIDSVAX B/E vaccine dose (A03-A15). Averages from 4 replicates tested in 2 independent experiments are shown. (a,b) Kinetics of Ab responses induced to V3 crown, V3 cradle, and V3 ladle peptides in VAX003 (a) and VAX004 vaccinees (b). OD₄₀₅, optical density at 405 nm. Percentages of responders (% positive) are shown below each graph. Cutoff values (black dotted lines) were calculated as mean and 3 standard deviations of placebo recipients. Mean antibody levels are highlighted in bold black lines. *P < 0.05, **P < 0.01, ***P < 0.001; NS: not significant by t test (paired, 2-tailed). (c,d) In the vast majority of VAX003 (c) and VAX004 (d) vaccine recipients, Ab responses against V3 crown and V3 cradle arose after 2 to 3 doses and declined by > 30% with subsequent doses. Data from representative individuals (mean ± standard deviation) with sustained versus not sustained responses are shown.