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. 2016 Sep 2;197(7):2726–2737. doi: 10.4049/jimmunol.1600674

FIGURE 4.

FIGURE 4.

FLSC boosting increased Abs directed to the V2 loop of gp120. (A) Serum binding Abs to the gp-70 scaffolded V1/V2 proteins from SIVmac251WY (left) and SIVsmE660BR (right) measured 2 wk after the last vaccination. Significantly higher Abs are observed in the FLSC boosted animals compared with the gp120 boosted group evaluated by the Mann–Whitney–Wilcoxon test: p = 0.033 for both proteins. (B) Sequence of the V2 region of SIVmac251 and the 10 linear overlapping peptides that were used to map V2 responses. The sequence of peptide 24 is bolded. (C) Serum binding IgG titers to full-length cV2 peptides from SIVmac251 (left) and SIVsmE543 (right) measured 2 wk after the last vaccination. Significantly higher SIVsm cV2 Abs were seen in the FLSC group versus the gp120 group, p = 0.0001, whereas cV2 Abs to SIVmac251 approached, but did not attain, statistical significance: p = 0.074 measured by the Mann–Whitney–Wilcoxon test. (D) Binding Abs (IgG) in rectal secretions measured as resonance units to the full-length cV2 immunogens SIVmac251 (left) and SIVsmE543 (right) in vaccinated groups and controls. (E) Rate of SIV acquisition, shown as the percent infected after weekly intrarectal exposure to SIVmac251. ALVAC-SIV/gp120 vaccinated significantly decreased the rate of SIV acquisition compared with controls (p = 0.02) measured by the score test of the discrete time proportional hazards model. (F). SIV acquisition in the ALVAC-SIV/gp120 group dichotomized based on the presence or absence of cV2 Abs (IgG) to SIVsm in the rectal secretions (left panel). Animals with detectable rectal IgG to SIVsm had a slower rate of SIV infection, p = 0.0018, measured by the score test of the discrete time proportional hazards model. In the middle and right panels, animals in each group were dichotomized based on whether their serum cV2 or linear V2b peptide response fell above or below the 25th percentile. If the response was below the 25th percentile, the animals were considered low responders. ALVAC-SIV/FLSC–vaccinated animals with cV2 (middle panel) and V2b responses (right panel) above the 25th percentile had a slower rate of SIV infection (p = 0.0016 and p = 0.008), measured by the score test of the discrete time proportional hazards model. The data for the ALVAC-SIV/gp120 group (A and C–F) have been previously reported (24).