Plasma viral RNA levels after SIVmac239 infection. Viral load (VL) traces for individual animals in group 1 (A), group 2 (B), and group 3 (C). VLs were log transformed and correspond to the number of vRNA copies/milliliter of plasma. The dotted lines in all the graphs are for reference only and indicate a VL of 103 vRNA copies/ml. The dashed lines are also for reference only and denote a VL of 106 vRNA copies/ml. The pink rectangle in each graph frames the interval during which five group 2 vaccinees controlled viremia to <15 vRNA copies/ml. Groups 1, 2, and 3 are color-coded in blue, black, and red, respectively.