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Real time PCR allows simultaneous amplification and quantification of PCR products.
The amplified fragment of parainfluenza 3 virus DNA can be detected using a molecular beacon (a short chemically synthesised single-stranded oligonucleotide 21 b.p. long) complementary to the inner part of the amplified fragment of the virus that carries a fluorescent label at the 5'-end and a fluorescence quencher at the 3'-end. The beacon undergoes a conformational reorganization in the course of PCR, as the fragment of the virus is amplified and forms a hybrid complex with the beacon, spatially separating the fluorescent label and quencher, thus exposing the fluorescent label. By measuring the fluorescence intensity, the results of PCR amplification can be visualized without gel electrophoresis.
A major advantage is that reaction tubes stay closed during fluorescence measurements, which prevents contamination of the PCR products.
The test system allows differentiation between parainfluenza 3 virus and herpes virus type 1, diarrhoea virus and adenoviruses.
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