MOLECULAR METHODS AND PLATFORMS FOR INFECTIOUS DISEASES TESTING
Molecular assays have considerably improved the field of infectious disease diagnostics, especially with the superior responsiveness and specificity linked by presenting clinical laboratories with accurate and rapidly obtained results. Recent advancements in Molecular Diagnostics and the availability of commercial Nucleic Acid Amplification Techniques (NAATs) based assays have transformed the way researchers perform laboratory diagnosis of infectious disease testing.
Diagnostic tests play a significant role in the clinical care of patients with contagious diseases, including detecting specific pathogens, discovering new pathogens, determining appropriate therapy, monitoring response to treatment, assessing prognosis, and disease surveillance. Even though the first direct-specimen molecular testing for infectious diseases was approved by the US FDA 26 years ago, there has been a recent explosion of molecular technology in two primary directions:
1.Next-generation sequencin
2.Direct-specimen rapid amplification and detection and platforms
The BioFire FilmArray pouch is a multiplex PCR assay that stores all the necessary reagents for sample preparation, reverse transcription PCR(rt pcr), PCR, and detection in a freeze-dried format. During a test run, the BioFire System extracts and purifies all nucleic acids from the unprocessed sample.
These high-level techniques offer an opportunity to provide medical laboratory diagnoses at a speed and sensitivity that was never possible with standard microbiology. The demand for diagnostics that promote clinical care and public health has never been more prominent. There is a significant chance of securing new technologies to address evident unmet needs.
PRINCIPLE OF MOLECULAR TESTING
The starting principle behind molecular testing involves amplifying the amount of DNA or RNA within a specimen of thousands to millions of times before analyzing. The DNA sequence is amplified using cycling methods, such as polymerase chain reaction (PCR) or isothermal amplification.
Molecular genetic testing is typically used to detect changes in a single gene and includes direct sequence analysis and large deletion/duplication detection. The amplification of DNA/nucleic acids is achieved using naturally occurring enzymes (proteins). DNA polymerase is one of the key enzymes used in this process, which is the basis for the qPCR assay methodology.
Other enzymes can be used for amplification, and these are typically grouped under the generic label of isothermal nucleic acid amplification tests (INAAT). The augmentation step makes molecular biology methodologies more receptive than immunological assays, and every amplification cycle doubles the amount of DNA in the sample. PCR detection involves amplification achieved through temperature cycling, while isothermal amplification assays use a uniform reaction temperature for amplification.
INFECTIOUS DISEASE TESTING
Over 30 new infectious diseases have been identified during the last three decades, making it imperative to have a reliable method to determine the responsible pathogens. Access to sensitive and rapid infectious disease assays is essential for accurate diagnosis, effective treatment, and timely infection control. Let’s look at some of the infectious diseases
Hepatitis C virus (HCV) disease is the most prevalent cause of chronic viral hepatitis. Almost 20% of the 4 million carriers develop liver cirrhosis. HCV infections are usually diagnosed by detecting antibodies aimed against specific HCV antigens.
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