The phrase "polymerase chain" refers to a process in which a special enzyme called polymerase makes copies of a specific section of DNA. It is like creating many identical copies of a particular DNA sequence. Full definition
A far more sensitive test using polymerase chain reaction could prove whether the HIV virus itself was present in the vials. (discovermagazine.com)
The clinic works with the Bedford Research Foundation in Boston, Massachusetts, which has developed a technique using polymerase chain reaction (PCR) assays to detect the HIV virus in semen. (surrogacyusa.com)
These are the Real Time Polymerase Chain Reaction Tests (RT - PCR) that identify minute amounts of pathogen genetic material without having to grow the organisms in the laboratory. (2ndchance.info)