TABLE 2.

Effect of DNA background on the amplification of A. phagocytophilum

DilutionaThreshold cycles (Ct) in various DNA backgroundsb
WaterHumanTickMouse
10−319.2, 19.2, 19.618.8, 18.8, 18.818.3, 18.6, 18.918.8, 18.7, 18.9
10−422.1, 22.4, 22.522.1, 22.0, 21.921.4, 21.4, 21.721.7, 21.6, 21.7
10−526.9, 26.9, 27.225.8, 25.7, 25.325.1, 25.0, 26.125.0, 24.8, 24.7
10−630.1, 30.2, 30.529.4, 29.0, 29.129.3, 29.0, 29.428.6, 29.1, 28.5
10−734.1, 34.1, 33.533.8, 32.7, 33.332.8, 32.4, 33.134.0, 33.8, 32.8
  • a Values represent the dilution factor using DNA extracted from A. phagocytophilum strain USG3 grown in HL-60 cells. The diluent for each dilution series consisted of undiluted DNA extracted from 200 μl of EDTA-treated whole blood (human), a single adult I. scapularis tick (tick), or 50 μl of EDTA-treated whole blood (mouse).

  • b Each value represents the threshold cycle from one of three separate real-time multiplex PCR amplifications.