Nucleic acid detection

Abstract

Abstract All viruses contain either an RNA or a DNA genome which can be detected with a suitably designed and prepared complementary probe. Specific binding of the probe to the target is accomplished by adjusting the stringency temperature, salt concentration, and/or formamide concentration-of the hybridization and post-hybridization washing conditions. The probe is usually tagged with a radioactive tracer, with a hapten such as biotin or digoxygenin or with an enzyme such as alkaline phosphatase. The signal from the tracer is captured on X-ray film or developed as coloured substrate on a solid phase. It is sometimes possible to quantify this signal to give an estimate of the number of virus genomes present in the sample. There is an absolute limit of sensitivity of direct hybridization of 104- 105 molecules, depending on the size of the target genome.