Life beyond PCR: alternative target amplification technologies for the diagnosis of infectious diseases, part I

Non-PCR-based target amplification technologies, including transcription-mediated amplification (TMA), nucleic acid sequence-based amplification (NASBA), and strand displacement amplification (SDA), are currently the basis for a broad range of clinical infectious-disease molecular diagnostics. These amplification technologies are very sensitive and specific and can be used in combination with traditional end-point or "real-time" detection formats. For several nucleic acid targets, TMA, NASBA, and SDA have certain advantages over PCR-based applications. This two-part article will review the molecular basis of each technology and how the technology has been applied to clinical diagnostic systems. The articles will describe the current testing platforms available, U.S. Food and Drug Administration (FDA)- and non-FDA-approved assays, and availability of analyte-specific reagents. In addition, an open-platform system is described that utilizes standardized reagents and methods and allows the user to develop in-house protocols. Finally, applications for the future are discussed.