Figure 1.

Immune responses and virus burden at set-point (56 days after inoculation) for immunized and control animals challenged by intrarectal inoculation with SHIV89.6PD. Samples collected before challenge were characterized for anti-Tat serum antibody titers (reciprocal of greatest dilution that was positive by ELISA) and Tat-specific lymphoproliferative responses (stimulation indices). Data were separated according to the plasma viral burden at 56 days after infection (set-point); A shows low viral burden (open symbols), and B (closed symbols) shows high viral burden. Symbols indicate whether animals were immunized with Tat toxoid (circle), Tat toxoid plus gp160 (square), Tat (triangle), or Group B control (asterisk). Data points are labeled with the animal identification numbers.