Nucleic acids diagnostic probes

Triplex, quadruplex, and nucleic acid analog probes hold promise for assays of improved sensitivity and specificity. To date, limited use has been made of nucleic acid analogs as probes even though the advantages of some structural types for antisense therapeutics may extend to diagnostic applications. The use of such probes will increase specificity and sensitivity of probe hybridization assays. 

Deshpande, S. S. Sharma, . P. Diagnostics. Immunoassays, nucleic acid probes, and biosensors — two decades of development, current status, and future projections in clinical, environmental, and agricultural applications, Diagnostics in the year 2000. Antibody, Biosensor, and Nucleic Acid Technologies , Eds. Singh, P. Sharma, . P. Tyle, P. Van Nostrand Reinhold New York, 1993, pp. 459-525. 

Recently, introduction of DNA analogous detection systems such as the use of peptide nucleic acid (PNA) technology has attracted considerable attention [10]. The PNAs are synthetic analogues of DNA that hybridise with complementary DNAs or RNAs with high affinity and specificity, essentially because of an uncharged and flexible polyamide backbone. The unique physico-chemical properties of PNAs have led to the development of a variety of research and diagnostic assays where these are used as molecular hybridisation probes [11]. 

Hybridization of nucleic acid probes to membrane-bound target sequences is a commonly used technique in gene structure and expression analysis, medical diagnostics, and gene targeting. 

The following discussion is focused on in vitro applications of monoclonal antibodies and nucleic acid probes as diagnostic reagents. The principles of production and characteristics of Mabs are described in Chapter 2. Their use as in vivo diagnostic imaging agents has been discussed in Chapter 3 in the context of therapeutic applications, and is not discussed further here. The principles of PCR and nucleic acid hybridization have been discussed in Chapter 2 and Chapter 4, respectively. 

Nucleic acid probe methods which rely on the specificity of nucleic acid hybridization reaction, combined with the powerful methods of nucleic acid amplification, are expected to spawn many new diagnostic tests which may be useful in the detection and treatment of infectious diseases, cancer, and inherited disorders. The impact of development and applications of diagnostic tests based on nucleic acid probes and on Mab technology wiU be felt increasingly as deeper understanding of diseases at a molecular level is gained. 

Nucleic acids are also valuable as diagnostic reagents. In combination with the recently developed amplification method, polymerase chain reaction (PCR), nucleic acid probes allow the detection of trace amounts of a specified nucleic acid sequence. Thus, the presence of the DNA of pathogens can be ascertained with great sensitivity and rapidity. Further, these tools permit the analysis and the detection of gene defects in individual patients, and aid in the tailoring of therapeutic strategies. These applications are discussed in Chapter 8. 

Nucleic acid hybridization is based on the precise nucleotide base pairing and hydrogen bonding between one string of nucleotides and a complementary nucleotide sequence. Any diagnostic nucleic acid hybridization test has three essential elements the DNA probe, the target DNA and the signal detection system. Recent developments in detection systems and improvements in safety have enabled... 

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