Figure 4. Vaccination of macaques with Vaxfectin^® adjuvanted SIV env DNAs induces high sustained binding and neutralizing antibody titers. (A) Outline of the Vaxfectin^® adjuvanted SIV env DNAs vaccination in macaques. (B, C) Reciprocal endpoint binding Ab titers to SIVmac251 (B) and SIVmac239 (C) Envs are shown in log. (D) Comparison of peak bAb responses (2 weeks after 3 SIV env DNA vaccinations) to SIVmac239 Env obtained upon Vaxfectin^® adjuvanted env DNA delivery and IM/EP env DNA delivery (0.5 or 2 mg env DNA; reported previously²⁸ and our unpublished observation). Mean and SEM are given. (E) Analysis of linear peptide responses at 2 weeks post V7 from the plasma samples of the vaccinated macaques using 20-mer overlapping by 14 AA. (F-L) Neutralizing antibody titers against SIVmac251-TCLA measured in M7-Luc cells (F). Neutralizing antibody titers against pseudotyped viruses having the following Env: transmitted SIVmac251 Env 35014 (M766) (G) and 35014_7 (H), the heterologous SIVsmE660 Env CG7G (I) and CG7V (J) were measured using the TZM-bl assay. Arrows indicate env DNA vaccinations (V5-V7). Neutralization titers shown are the log of the reciprocal dilution of sample that reduced the signal by 50% compared with virus in the absence of sample.