Watch this video to learn how researchers at Sangamo BioSciences use Bio-Rad's QX100 Droplet Digital PCR system to quantify the level of HIV reservoir in treatment subjects with their unique zinc-finger-based therapy. At approximately one copy of HIV in 1,000 cells analyzed, this quantification would present a challenge for conventional methods. The Droplet Digital PCR system allows for the quantification of target DNA with unrivaled precision by partitioning samples into 20,000 nanoliter-sized droplets. After PCR on a thermal cycler, PCR-positive and PCR-negative droplets are counted to provide absolute quantification of the target DNA. The QX100 Droplet Digital PCR system is the third generation of PCR technology and provides an absolute measure of target DNA molecules with unrivaled accuracy, precision, and sensitivity.