Figure 6. .
Preamplification conditions before quantitative polymerase chain reaction (QPCR) and range of detection for inhibition of hepatitis B virus (HBV) amplification in plasma. A, No. of cycles used for preamplification (preamp) for each respective amplicon length. The longer the amplicon, the more cycles were needed to generate the same no. of copies. B, Validation of assay and determination of log range sensitivity for HBV controls. QPCR confirmed the equal amount of DNA product produced with each preamp condition. Those with no preamp were not subjected to preamp and constituted the baseline control, consisting of only QPCR with a 80‐bp amplicon. The preamp products of each amplicon length showed an ∼4‐log range of amplification. The broader log range is attributed to the increased preamp cycle numbers used in the HBV assay. Ct, cycle threshold.