FIG 1.

Immunization and challenge scheme. As detailed in Materials and Methods, 50 macaques (24 females and 26 males) were primed mucosally at weeks 0 and 12 with replication-competent Ad5hr recombinants separately encoding SIV_M766 gp120-TM and SIV₂₃₉ Gag. Ten controls (4 females and 6 males) received empty Ad5hr vector. Subsequently, at weeks 24 and 36, macaques in the ALVAC/Env group (n = 25; 12 females and 13 males) were boosted systemically with ALVAC-SIV_M766 Gag/pro/gp120-TM in one thigh and gD-SIV_M766 gp120 and gD-SIV_CG7V gp120, both in alum hydroxide, in the opposite thigh. Macaques in the DNA&Env group (n = 25; 12 females and 13 males) were boosted systemically with DNA encoding SIV_M766 gp120-TM, SIV₂₃₉ Gag, and macaque IL-12, followed by electroporation and immediate intramuscular administration of the same SIV gD-gp120 proteins in alum phosphate at the same anatomical sites. Control animals (5 in the ALVAC/Env group and 5 in the DNA&Env group) received alum hydroxide or alum phosphate only. At week 42, weekly repeated low-dose intrarectal challenges with SIV_mac251 (1:500 dilution; 120 times the TCID₅₀) were initiated. All macaques received up to 15 challenges until infection occurred. O, oral; IN, intranasal; IT, intratracheal; IM, intramuscular; IR, intrarectal.