cycles of denaturation at 95 °C for 30 sec, annealing at 55 °C for 1 min and extension for 1 min, followed by a final last incubation at 98 °C for 10 min and storage at 4 °C. After amplification, the ddPCR™ 96-well-plate was placed into a plate holder into the QX200™ Droplet Reader. PCR-positive and PCR-negative droplets of each sample were analyzed and fluorescent signals of each droplet were counted and quantified.