How Molecular Diagnostics Can Help Us Fight Against Infectious Diseases

Author: James Briggs, Sales & Marketing Manager – Molecular Biology

Have you ever wondered how molecular diagnostics can help us fight against infectious diseases? Molecular diagnostics is a field of laboratory medicine that uses molecular-based techniques to investigate human, viral and microbial genomes⁽¹⁾.

In the context of infectious disease testing, molecular diagnostics are used to detect, identify, and characterise microscopic invaders, such as viruses and bacteria, in our body. The technique can also tell us more about their characteristics, such as their strain type, drug resistance, and transmission patterns. This can help us make better clinical decisions, improve patient outcomes, and prevent disease outbreaks. Sounds amazing, right?

However molecular diagnostics within any pathology discipline is not a simple process. It involves many steps, such as preparing the sample, extracting the genetic material, amplifying it, analysing it, and interpreting the results. These steps can be time-consuming, complex, and costly if done manually or with separate instruments. They can also introduce errors and variability that can affect the accuracy and reliability of the results.

That’s where complete sample-to-result systems come in. These are instruments that integrate all the steps of molecular diagnostics into one device. They can automate the whole process from sample loading to result reporting without any user intervention. They can also simplify the workflow, reduce manual handling, ensure quality control, and increase throughput. Some of these systems are even portable, so they can be used at the point of care, where patients need them the most.

In this piece, we will focus on how complete sample-to-result molecular diagnostics systems can be applied in virology and microbiology, two fields that deal with the study of viruses and bacteria. We will also introduce you to the GeneLEAD VIII platform from Precision System Science (PSS), a new benchtop instrument that offers a fully automated sample-to-result solution for molecular testing based on qPCR analysis.

The Benefits of Complete Sample-to-Result Systems in Virology and Microbiology

Molecular diagnostics can help us detect and characterise pathogens at a molecular level. For example, it can tell us:

• What kind of pathogen is causing the infection (e.g., virus or bacteria)
• What strain or type of pathogen is involved (e.g., SARS-CoV-2 or E. coli)
• How resistant the pathogen is to drugs (e.g., penicillin or azithromycin)
• How virulent (harmful) the pathogen is (e.g., mild or severe)
• How related the pathogen is to other pathogens (e.g., same or different origin)

This information can help us diagnose infections accurately, treat them effectively, and prevent them from spreading.

But how do complete sample-to-result systems achieve this? Well, they integrate and use various techniques that are based on molecular biology principles. Some of these techniques are:

• Polymerase chain reaction (PCR): This technique copies a specific DNA sequence using primers (short pieces of DNA) and a DNA polymerase enzyme (a protein that builds DNA) ⁽²⁾. In conventional PCR, the amplified DNA product is detected in a qualitative, end-point analysis (yes or no answer).
• Real-time PCR/Quantitative PCR (qPCR): An advanced version of standard PCR, allowing amplification monitoring in real-time. It accurately measures the initial quantity of template DNA copies across a wide range. The results can be qualitative (presence or absence of sequence) or quantitative (number of copies)^{(3, 4)}. The process uses fluorescent probes or dyes that bind to replicated DNA, producing an intensifying fluorescence signal as the DNA quantity increases.
• Reverse transcription PCR (RT-PCR): This technique converts RNA into DNA using a reverse transcriptase enzyme (a protein that builds DNA from RNA) before copying it by PCR⁽²⁾. It’s commonly used for RNA viruses like SARS-CoV-2.
• Multiplex PCR: This technique copies multiple DNA targets at once using different sets of primers in a single reaction⁽²⁾. This makes testing more efficient and specific.

Molecular diagnostic tests are powerful and innovative, but they require high-quality and high-yield nucleic acid extraction from varying sample types and volumes to ensure the quality of test results. To achieve this, complete sample-to-result systems use magnetic bead-based methods for extraction and purification. Magnetic bead-based DNA extraction has several advantages that make it an excellent choice for clinical diagnostics^{(5, 6, 7, 8)}.

The GeneLEAD VIII Platform: A New Solution for Molecular Testing Based on qPCR Analysis

The GeneLEAD VIII platform from Precision System Science (PSS) is a system that uses magnetic bead technology to extract and purify high-quality nucleic acid, making it a perfect fit for testing in the fields of virology and microbiology.

As a new entrant in the realm of benchtop instruments, the GeneLEAD VIII platform is unique in its ability to perform nucleic acid extraction and qPCR detection of a wide array of pathogens. It does this directly from clinical samples, all within a single instrument⁽⁹⁾. The platform offers a range of features and benefits that make it an ideal choice for various applications. Let’s take a closer look at these in more detail:

• Open platform: The GeneLEAD VIII is an open platform that can accept user-specified qPCR reagents and protocols. A growing portfolio of off-the-shelf CE IVD kits that include both extraction and qPCR reagents for the detection of various pathogens is also available.
• Three operation modes: The platform can perform in three different modes of operation according to the required application: extraction + PCR, extraction only, or PCR only. This can provide flexibility and versatility for molecular testing.
• Parallel processing: Up to eight samples can be processed in parallel using independent lanes. Each lane can have independent temperature control and six-colour fluorescence detection for multiplex qPCR analysis (FAM, HEX, ROX, TAMRA, Cy5, Cy5.5), meaning that a separate PCR program can be selected individually for each sample in the same run. The platform can also process different sample types with a single extraction reagent.
• Solid contamination control: It is a hands-free and enclosed system that prevents contamination between samples and reagents. The platform also has a capping mechanism for the PCR zone, UV light decontamination, and HEPA filter to ensure a clean environment for molecular testing.
• User-friendly operation: Controlled by a single, external laptop that can connect up to six units of the instrument for increased throughput. The platform can also be connected to LIMS-compatible software for data management and reporting. Onboard QR code and barcode reading ensure the traceability and integrity of samples, controls and reagents.

The GeneLEAD VIII platform is now available in the UK and the Republic of Ireland through VH Bio. If you are interested in learning more about the GeneLEAD VIII platform or requesting a demonstration, please contact us at [email protected].

References:

1. Hendrix, E. and Rohde, R. (2021) Molecular Diagnostics: The Future of Laboratory Medicine. American Society for Microbiology. Available at: https://asm.org/Articles/2021/July/Molecular-Diagnostics-in-the-Medical-Laboratory-in (Accessed: 10 October 2023)
2. Yi-Wei Tang, Gary W Procop, David H Persing, Molecular diagnostics of infectious diseases, Clinical Chemistry, Volume 43, Issue 11, 1 November 1997, Pages 2021–2038, https://doi.org/10.1093/clinchem/43.11.2021
3. Acharya, T. (2023) Real-time PCR also called quantitative PCR (qPCR). Microbeonline. Available at: https://microbeonline.com/real-time-pcr-principles-and-applications/?utm_content=cmp-true (Accessed: 11 October 2023)
4. Bio-Rad Laboratories. (2023). What is Real-Time PCR (qPCR)? Available at: https://www.bio-rad.com/en-uk/applications-technologies/what-real-time-pcr-qpcr?ID=LUSO4W8UU (Accessed: 11 October 2023).
5. Gane, A. (2023) Magnetic beads: a guide to their chemistry, properties and applications. Cytiva. Available at: https://www.cytivalifesciences.com/en/us/news-center/magnetic-beads-a-simple-guide-10001 (Accessed: 10 October 2023)
6. Gilson (2023) Magnetic beads: a guide to their chemistry, properties and applications. Available at: https://gb.gilson.com/learninghub/post/a-guide-to-using-magnetic-beads-for-rna-and-dna-extraction.html (Accessed: 12 October 2023)
7. Gautam, A. (2022). Magnetic Bead-Based Nucleic Acid Isolation. In: DNA and RNA Isolation Techniques for Non-Experts. Techniques in Life Science and Biomedicine for the Non-Expert. Springer, Cham. https://doi.org/10.1007/978-3-030-94230-4_15
8. He, H. et al. (2017) Integrated DNA and RNA extraction using magnetic beads from viral pathogens causing acute respiratory infections. Scientific Reports, 7, 45199. https://doi.org/10.1038/srep45199.pdf
9. geneLEAD VIII: PSS (2023) Fully Automated Sample-to-Result Instrument for Molecular Testing. Available at: https://www.pssbio.com/genelead-series/genelead-viii/ (Accessed: 10 October 2023).