Quantitative ILPCR dose–response curve for p24 added to PBS buffer. A 100-μl sample volume (antigen diluted in PBS) was used for all concentrations. The black circles are the average of three replicate Ct measurements over a concentration range of 10-7 to 10-17 M p24; the standard deviations of the Ct values are shown as blue vertical bars. In order to be visible, the standard deviations were multiplied by the following values: 10-7 M (3x), 10-9 M (1x), 10-11 M (5x), 10-13 M (5x), 10-15 M (7x), and 10-17 M (1x). The remaining symbols and colors have the same designations as given in Figure 4.