Laboratory diagnosis of viral infections :Molecular methods (nucleic acid detection)

A wide variably of commercial assays are available to detect viral nucleic acid directly or after amplification. These procedures are rapidly becoming the standards for diagnostic virology and it is more sensitive than antigen detection and cultures include polymerase chain reaction (PCR), Reverse -Transcriptase PCR and others. These procedures allow detection of viruses (e.g. Enteroviruses) as well as quantitation of the viruses (e.g. CMV, HIV) which guide antiviral therapy. The principle is the hyperdization of nucleic acid probe (single strand DNA or RNA) to specific nucleic acid sequence in the specimen followed by detection of the paired hybrid. The probe is labeled with enzyme, chemiluminescent molecule, or radioisotopes to facilitate detection of the hyperdization product