TABLE 2.
Details about the compared real-time PCR assays
Assay | Cycling structure | Enzyme/buffer (source) | Primer/probe concn. | Detection |
---|---|---|---|---|
Conventional PCR | 95°C for 5 min, 45 cycles of 95°C for 15 s, 65°C for 15 s, 72°C for 1 min, 72°C for 10 min | AmpliTaq Gold/AmpliTaq Gold PCR Master Mix (Applied Biosciences, Foster City, Calif.) | 0.4 μM of each primer | 2% agarose gel stained with ethidium bromide |
SYBR Green | 95°C for 15 min, 50 cycles of 95°C for 15 s, 60°C for 1 min, 72°C for 1.5 min, 80°C for 30 s + melting curve | HotStar Taq polymerase/QuantiTect SYBR Green PCR Master Mix (QIAGEN, Valencia, Calif.) | 0.1 μM of each primer | Fluorescence at the end of the 80°C incubation plateau and during the melting curve |
LightCycler | 95°C for 15 min, 50 cycles of 95°C, 58°C for 10 s,a 72°C for 20 s | HotStarTaq polymerase/ QuantiTect Probe PCR Master Mix (QIAGEN, Valencia, Calif.) | 0.5 μM of each primer/0.1 μM of each probe | Fluorescence at the end of each annealing plateau |
TaqMan1 and TaqMan 2 | 95°C for 3 min, 40 cycles of 95°C for 15 s, 60°C for 30 s, 72°C for 30 s | iTaq DNA polymerase/IQ Supermix (BioRad, Hercules, Calif.) | 0.5 μM of each primer/0.1 μM of each probe | Fluorescence at the end of each extension plateau |
A touch-down PCR mode was incorporated to stepwise decrease the annealing temperature from 62°C to 58°C during the first eight cycles.