Figure 5
Changes of virus-neutralizing activity detected in plasma of vaccinees during immunization. Plasma samples from VAX003 and VAX004 vaccinees (n = 9 total) were assessed for neutralization against SF162 pseudovirus. For each vaccinee, plasma from 3 time points was selected based on changes in ELISA anti-V3 Ab strength before peak, at peak, and at final A15 time point. Samples were tested in 2 to 4 replicates in 1 or 2 independent experiments. (a) Neutralization of titrated plasma from early, mid-, and last time points from 1 vaccinee. Averages and standard deviation are shown. Plasma was diluted 3-fold from 1:40 to 1:1080, and area under the curve (AUC) was calculated from the titration curve using Graphpad Prism version 7. (b,c) Neutralization activities (AUC ± standard error) at early, mid-, and final time points were compared. Most vaccinees displayed neutralization that peaked at mid-time points, coinciding with the peak of anti-V3 Ab responses, and declined after the final boost. Statistical comparison was performed using the ratio paired 2-tailed t test. *P < 0.05, **P < 0.01; NS: not significant.
