2.5. Sensitivity of multiplex osRT-PCR to detect polioviruses in stool extracts series of 10-fold dilutions (10−1 to 10−10) of Sabin 1, 2, and 3 virus suspensions containing 109 TCID50/ml and serial 10-fold dilutions (1011–10 copy/ml) of Sabin1, 2, and 3 construct plasmids were prepared in stool supernatant known to be free from poliovirus, and both serial dilutions were analyzed by multiplex and quantitative osRT-PCR assays.