Polymerase chain reaction (PCR) amplifies or copies 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 detection level. 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. It is mainly used to determine viral loads in chronic viral infections such as HIV and Hepatitis.
Reverse transcriptase PCR (RT-PCR) converts the RNA segments into cDNA segments. This method measures the amplified product and cannot detect the original amount of the sample genome.
As the name implies, multiplex PCR targets more than one sequence being amplified simultaneously in a single reaction. While the internal amplification controls ensure the accuracy of the negative result, this mixing of primers can cause cross-reactions if the genome sections used in the test are too large.
