TABLE 3.

Specificity of SQ-PCR assay for different genotypes of Rickettsia

IsolateCt value (mean ± SE)No. of DNA copies per T150 flask (mean ± SE)
R. rickettsii Bitterroot16.02 ± 0.0066.07 × 108 ± 0.02 × 108
R. montanensis OSU 85-93017.30 ± 0.422.49 × 108 ± 0.71 × 108
R. rhipicephali 12T17.17 ± 0.152.52 × 108 ± 0.29 × 108
R. parkeri HmacA15.96 ± 0.056.39 × 108 ± 0.24 × 108
SFG isolate 364-D16.40 ± 0.334.82 × 108 ± 1.23 × 108
R. slovaca B17.95 ± 0.201.41 × 108 ± 0.21 × 108
R. sibirica 24616.01 ± 0.396.49 × 108 ± 2.12 × 108
R. africae ETH SF-250017.32 ± 0.202.27 × 108 ± 0.32 × 108
Israeli tick typhus CDC14.87 ± 0.081.48 × 109 ± 0.09 × 109
Astrakhan spotted fever A-116.97 ± 0.233.00 × 108 ± 0.57 × 108
R. honei TT11818.88 ± 0.347.17 × 107 ± 2.03 × 107
R. akari Hartforda>37<1
R. australis JCa>37<1
R. bellii 369C42a>37<1
R. canadensis McKiela>37<1
R. canadensis CA410a>37<1
R. prowazekii Breinla>37<1
R. typhi Wilmingtona>37<1
  • a rOmpA gene is absent from these rickettsiae or has low homology to the R. rickettsii rOmpA gene at the location of the primer sequences.