Molecular diagnosis is used to highlight the presence of viral nucleic acids and provides the possibility of rapid detection of viruses in samples taken from patients without requiring isolation and cultivation.
PCR technique (Polymerase Chain Reaction or gene amplification) – is most commonly used in practice; the technical principle is the amplification of the amount of nucleic acid, by obtaining a mixture of identical DNA strands between them. This is achieved by the action of an enzyme called DNA-polymerase, capable of synthesizing new DNA chains on an initial chain that plays the role of the template.
PCR tests can be of a qualitative PCR that results in a positive (viral nucleic acid present in the test sample) or negative sample (absent viral nucleic acid in the test sample) and quantitative PCR test when measuring the amount of nucleic acids in the test sample, called “Viral load”.
There are multiple variants of PCR technique, including techniques applicable not only to DNA genome viruses but also to those with RNA genomes such as the Rt-PCR technique (gene amplification reaction preceded by reverse transcription). In this reaction, the viral RNA initially serves as a template for the synthesis of a complementary DNA strands (revers transcription), followed by DNA amplification with the help of DNA polymerase .
About Corneliu Zaharia
