Table 1.

Absolute and relative detection limits of RT-PCR

Specimen typeExtraction methodSpecimen input/PCR mixtureAbsolute detection limit (no. of copies/PCR mixture)aRelative detection limita,bSample no.
PlasmaAmplicor 25 μl4.1 ± 0.1163.6 ± 5.9278
QIAamp500 μl7.4 ± 0.314.9 ± 1.6252
Cellsc RNeasy20–2,600 ng of RNA3.1 ± 0.2 NDd 97
RNeasy20–500 ng of RNA3.5 ± 0.5ND19
RNeasy900–1,100 ng of RNA2.3 ± 0.22.4 ± 0.2
RNeasy1,500–2,600 ng of RNA3.7 ± 0.3ND20
  • a Values are averages ± standard errors of the means.

  • b For plasma, the detection limit is number of copies per milliliter; for cellular specimens, the detection limit is number of copies per microgram of RNA.

  • c PBMCs and tonsil biopsy specimens.

  • d ND, not determined.