[Molecular diagnostics by automated systems].

Advent of molecular biology and biotechnology have realized and facilitated analyses for DNA or RNA sequences. New technological advances have led to the automation of major part of the assay process. Automated systems have been developed for amplification and detection of nucleic acid sequence for infectious agents, using polymerase chain reaction, ligase chain reaction, strand displacement amplification, transcription-associated amplification, and nucleic acid sequence-based amplification. Development of such automated systems are based on accumulation and integration of new molecular biotechnology. There has appeared a fully automated PCR system (COBAS AMPLICOR), which amplifies target nucleic acid sequence, captures the biotinylated and amplified products on oligonucleotide-coated paramagnetic microparticles, and detects the products with an avidin-horseradish peroxidase (HRP) conjugate. Automated systems provide improvement of not only labor efficiency but also assay accuracy. Contamination with the amplified products and difficulty in interpreting test results have been overcome with introduction of new technologies such as uracil N-glycosylase and positive internal control. Recently, the extraction of a specific sequence for hepatitis C virus (HCV) RNA has been automated, and the RNA can be specifically extracted from serum by hybridization with probe-coated paramagnetic microparticles, and then subjected to in vitro amplification. Automated systems for nucleic acid extraction from a variety of clinical specimens are now desired. To be practical, an automated system for each molecular diagnostic method must assure assay rapidity, quantification, quality control and cost effectiveness. It is also important to consider how to properly use or combine the molecular diagnostic methods for an efficient approach to the diagnosis of diseases.