Polymerase chain reaction (PCR) is an in vitro molecular biology technique used to amplify specific DNA sequences exponentially through repeated cycles of denaturation, primer annealing, and enzymatic extension by a thermostable DNA polymerase. In biopharmaceutical manufacturing and quality control, PCR and its variants — including quantitative PCR (qPCR), digital PCR (dPCR), and reverse transcription PCR (RT-PCR) — are widely used for identity testing, residual DNA quantification, viral vector genome titration, adventitious agent detection, and mycoplasma testing, and are essential tools in analytical methods development and batch release testing.
