Polymerase chain reaction (PCR) is used to amplify or copy a segment of RNA or DNA (nucleic acids). The target nucleic acid is copied using two synthetic primers (oligonucleotides) that bind to the sequence and then make new target sequences to a level of detection. There are usually about 30-35 cycles.
Real-time PCR (qPCR) is a quantitative method that uses fluorescent primers to determine the number of copies of the original target segment in the sample. This is used primarily for viral loads in chronic viral infections such as HIV and Hepatitis.
Reverse transcriptase PCR (RT-PCR) is used to convert the RNA segments into cDNA segments. This method measures the amplified product and is unable to detect the original amount of the sample genome.
Multiplex PCR, as the name implies, targets more than one sequence that is being amplified at the same time in a single reaction. While the internal amplification controls ensure the negative result accuracy, this mixing of primers can cause cross-reactions if the genome sections used in the test are too large.
