Highly Precise Measurement of HIV DNA by Droplet Digital PCR
Figure 4
Precision of ddPCR versus qPCR.
Samples of DNA (N = 156) isolated from the PBMC of patients during the first 6 months of cART were analyzed by both qPCR and ddPCR in triplicate. The reproducibility was higher for both the pol (a) and 2-LTR (b) targets. Because the noise and stochasticity of all assays varies with copy number, the relative precision was assessed by averaging the coefficient of variation within small bins (Fig. S2 (b)). The average coefficient of variation was 4-fold lower by ddPCR (Fig. S4 (b)) and 20-fold lower for 2-LTR (Fig. S4 (c)). An imputed value of 6 copies/106 cells, equivalent to 1 copy/well, was used for wells in which no template was detected.