Figure 3From: Multi-pathogens sequence containing plasmids as positive controls for universal detection of potential agents of bioterrorismMolecular detection and identification of true and false positives using plasmid CatA as positive control. 3a. Not I predigestion of CatA plasmid DNA. A, B, C, D correspond to Not I digested-CatA plasmid DNA (overnight digestion with 10 U followed by an 1-hour digestion with another 10 U) respectively PCR amplified with Y. pestis, F. tularensis, B. anthracis, and smallpox virus oligonucleotide primers. E, F, G, H correspond to the same DNA samples which have not been digested by Not I. 3b. Discrimination of Y. pestis amplicons by Not I post-PCR digestion in a 3% agarose gel. lane I, Not I post-PCR digestion of amplicon from Y. pestis native DNA (101 bp); lane J, amplicon from CatA plasmid DNA (113 bp); lane K, Not I post-PCR digestion of amplicon from CatA plasmid DNA (digestion result in 2 products of 76 bp and 37 bp, respectively; only the 76 bp product is seen). 3c. Melting curves obtained from SYBR Green Light Cycler reactions. Curve A was obtained with CatA plasmid DNA and Y. pestis primers; curve B was obtained with Y. pestis DNA amplified with Y. pestis specific primers; curve C was obtained with Y. pestis DNA amplified in a multiplex reaction including the 8 primers specific for the category A agents (Y. pestis, F. tularensis, B. anthracis, smallpox virus). The melting temperature observed with A is 82.65 whereas it is 81.97 with native Y. pestis DNA (curves B and C).Back to article page