RNA-based isothermal amplification technology and its clinical application in pathogen infection

It is very important to detect pathogenic bacteria, viruses, or fungi in a patient's secretion or body fluid samples as soon as possible to determine the patient's recovery. For certain pathogens, the amount of ribosomal RNA copies contained is often tens of thousands of times higher than the amount of DNA copies, so the detection of RNA has higher sensitivity. In addition, whether for DNA pathogens or RNA pathogens, the direct detection of ribonucleic acid transcribed by pathogens in vivo can distinguish active infection or past infection, can eliminate the influence of residual DNA of pathogens that have died in the lesions, and can also avoid excessive medical interventions for transient infections, which is of great significance in the field of infectious pathogen detection. Isothermal amplification technology played important roles in molecular diagnosis because of its significant advantages. Highly sensitive RNA detection can be achieved by both direct transcription amplification and indirect amplification based on reverse transcription. Direct transcription amplification technologies relies on reverse transcriptase and T7 RNA polymerase to achieve linear transcription amplification of RNA on one-step; while the indirect amplification technology depends on a reverse transcriptional process at the beginning of the reaction. Both methods have outstanding advantages in clinical application, and commercial kits and commercial all-in-one machines based on these principles have been put into clinical use. This review mainly introduces the clinical application of isothermal amplification technologies in the detection of RNA pathogens and the main difficulties faced at this stage. It is hoped to provide insightful ideas for the construction of pathogen RNA detection technology to meet the needs of point-of-care testing in the future.