Figure 1. Schematic representation of the immunization regimen, sample collection and SIV challenges.

Sixty rhesus macaques included in this study were subdivided into 4 groups: vaccine + SAMT-247 (n=20), vaccine only (n=18), SAMT-247 only (n=12) and controls (n=10) (lower box). Thirty-eight animals were mucosally primed with Ad5hr-SIV recombinants encoding Env/Rev, Gag and Nef and systemically boosted with SIV gD-gp120 proteins in alum hydroxide at the indicated timepoints. Twenty-two animals received empty-Ad5hr vector and alum hydroxide only as placebo controls at the same timepoints. Beginning at week 45, protective efficacy against SIV_mac251 was assessed by subjecting all animals to up to 15 weekly intravaginal viral exposures (black arrows) in the presence or absence of SAMT-247 until infection was confirmed. Animals either received 0.8% SAMT-247 in HEC gel (n=32) or HEC gel only (n=28) 3 hours prior to each low-dose SIV_mac251 challenge. The different tissue samples collected 4 weeks before the first prime (Minus 4 wks), and 3 days (3d), 14 days (14d) or 21 days (21d) following immunizations are represented by different symbols as shown in the figure. IN = intranasal; O = oral; IT = intratracheal; IM = intramuscular