The polymerase chain reaction (PCR)1,2 has revolutionized the detection of bacterial, fungal, and viral pathogens. The targeted amplification of nucleic acid sequences provides not only dramatic increases in the number of copies to be detected but concomitantly provides a nearly equivalent reduction in the complexity of the nucleic acid to be probed. Either DNA or RNA (following the production of complementary DNA using reverse transcriptase) can be used as a template for amplification. Further, since PCR is a target rather than a signal amplification system, the benefit of the variety of procedures developed over the years to amplify signal can be exploited coincidentally. Combined, these aspects of PCR allow ready detection of single pathogenic organisms or virus particles, an accomplishment provided earlier by procedures employing the in vitro propagation of such pathogens. However, since the exponential amplification of PCR is catalyzed by a biochemically simple cyclical process requiring less than minutes per cycle, this procedure promises to supplant the culturing of a pathogen which frequently requires a total elapsed time of days to weeks. By definition, pathogens not capable of in vitro propagation, for example because of the inability to culture a specific host cell for a virus, are refractory to detection using this approach. Polyclonal and monoclonal antibodies used in a diagnostic setting typically recognize haptens found in multiple copies on a pathogen to circumvent the need to replicate the desired pathogen.
Weitere Kapitel dieses Buchs durch Wischen aufrufen
- Application of PCR to the Detection of Human Infectious Diseases
John J. Sninsky
- Palgrave Macmillan UK
- Chapter 19