A safe and easy sample collection and transport mechanism is essential to support the increase in COVID-19 testing globally. Learn how PrimeStore® MTM, a novel viral transport media, enables safe molecular testing for multiple pathogens from one sample swab compared to standard viral transport media.
The main difference between MTM and VTM is that molecular transport media, such as PrimeStore® MTM, entirely deactivate viruses, bacteria, fungi, and mycobacterium tuberculosis. This allows safe sample handling and transport and significantly reduces infection risk.
This novel FDA-cleared and CE IVD-marked infectious disease sample collection, storage, and transport system was specifically developed to overcome the shortcomings of standard viral transport media (VTM) and universal transport media (UTM). These do not inactivate microbes and can also inhibit molecular testing.
What is Molecular Transport Media?
PrimeStore® MTM (molecular transport media) is designed to safely inactivate pathogenic samples while preserving and stabilizing the released DNA and RNA. The guanidine thiocyanate contained in Primestore® MTM destroys a virus’s protective viral coat (the capsid), rendering it incapable of reinfection whilst maintaining the viral nucleic acids for molecular diagnostics, sequencing, and biobanking.
Molecular testing is now widespread due to its improved performance and turnaround times compared to traditional microbiology testing. Most currently approved tests for COVID-19 (SARS-CoV-2) and other infectious diseases are nucleic acid-based molecular assays, removing the need for and risk of live pathogen transportation for routine testing.
Designed and optimized for molecular applications, including qPCR and next-generation sequencing, PrimeStore® MTM uses a unique patented technology for safely collecting samples from patients with highly infectious diseases. It was first introduced in 2006 in preparation for a worldwide pandemic. It has already been used in testing for many infectious diseases and high-consequence pathogens, including influenza, RSV, TB, HIV, and coronavirus.
COVID-19 has led to a significant increase in global demand for PrimeStore® MTM, the only FDA Class II cleared device for microbial nucleic acid storage and stabilization (RNA and DNA) available for the safe transportation of samples that may contain viruses. There are already several published examples of its use in the workflow for SARS-CoV-2 RNA detection, where it is used for initial virus inactivation [1].
Advantages of MTM over VTM and UTM
PrimeStore® MTM is seen as a game-changer in the sampling and transport of pathogenic samples from a safety, reliability, and cost perspective.
Standard UTM and VTM media were designed to transport intact, viable microbial samples for culture. This means that there is still a biohazard, which requires a controlled environment for subsequent laboratory work. Furthermore, cold chain storage and transportation are needed as samples are live.
These standard transport media may also contain enzymes and nucleases that damage RNA and DNA, inhibiting optimal molecular testing, such as PCR. However, modern molecular tests do not require viable viruses but just intact microbial nucleic acids.
Once a swab or biofluid is added to PrimeStore® MTM, the user has a ‘snapshot’ in time for that inactivated microbial sample. The microbe’s DNA, and more importantly, the labile RNA, is immediately stabilized and preserved at the sampling point. So, samples in MTM do not have to be pre-processed in BLS-III or even BLS-II safety levels; just safe everyday laboratory practices for testing are required.
Another key benefit of MTM is that a sample can be safely stored at ambient temperature for up to seven days or 28 days at 2 to 8°C and reused several times. This reduces the risks of handling live pathogenic samples and cuts costs by eliminating the cold chain requirement and, as mentioned above, the need for Category 3 facilities, as testing can occur outside containment.
Combined COVID-19 and flu testing
A strong testing programme is needed to prepare for flu season and a potential second wave of COVID-19, as thousands of people will start presenting with symptoms that could be flu or coronavirus.
Multiple infectious disease tests can be processed from one sample swab, making PrimeStore® MTM ideal for the approaching flu season. Samples collected and stored in MTM can be tested for COVID-19 and influenza from a single inactivated and stabilised swab sample. In addition to the fact that refrigerated transport and storage are not required, this can assist with disease differentiation at reduced costs compared to standard collection kits.
Proven safe viral transport
PrimeStore® MTM is proven technology. With millions of tubes already sold globally to hospitals and laboratories during and before the COVID-19 pandemic, it is evident that they trust it to provide safer and more reliable testing than generic VTM or universal transport media, saline, or RUO devices.
Multiple peer-reviewed scientific papers have been published from 2011 onwards, validating the use of PrimeStore® MTM for reliable pathogen deactivation and detection from various clinical matrices and biofluid types and with various analytical platforms. A selection of these references is available.
Recently, a consortium of researchers put forward the case for biosafety in pathogen transportation and testing by adopting virus-inactivating VTM, which kills biological pathogens whilst ensuring DNA and RNA stabilization and preservation for molecular applications.
They noted that PrimeStore® MTM has been extensively analysed to effectively inactivate/kill viral, bacterial, and fungal pathogens while preserving the stability of the released DNA and RNA for diagnosis, and is FDA-cleared. They also observed that: “Moving to virus-inactivating VTM at collection allows risk mitigation from transportation and handling of bio-specimens for diagnosis and can potentially reduce the need for special packaging and transportation measures for SARS-CoV-2/COVID-19 test samples.” [2]
Not all inactivation media are equal
As discussed above, working safely with live human coronavirus SARS-CoV-2 requires high-containment laboratories. However, SARS-CoV-2 material can be handled at a lower containment level after inactivation, thereby opening up testing capacity in more laboratories.
A recent study by Public Health England [3] investigated a wide array of apparent inactivation reagents in current use in UK laboratories during the COVID-19 pandemic for sample transportation and subsequent molecular processing. 23 commercial reagents designed for virus inactivation, clinical sample transportation, and nucleic acid extraction were assessed for their ability to inactivate SARS-CoV-2.
TCID50 and blind passage techniques were used to test for any infectious virus still recoverable from all samples treated with the inactivation reagents. Results showed that of the specimen transport reagents tested, PrimeStore® MTM was one of just two reagents from which no residual virus was detectable by either TCID50 or the passaging of treated purified sample.
In conclusion
The novel, patented sample collection device, PrimeStore® MTM, allows COVID-19 samples to be rapidly inactivated in the collection tube. This immediately eliminates infection risk and preserves nucleic acids for downstream molecular processing without refrigeration.
In addition to removing the need for expensive cold chain transport and storage of samples, PrimeStore® MTM perfectly preserves RNA and DNA for up to four weeks. This means it is ready for safe testing immediately upon arrival at a laboratory and without containment. In the case of COVID-19, this opens up options for more testing laboratories, making this device a key part of the testing supply chain that can underpin the safe and rapid increase of testing capacity.
PrimeStore® MTM is also being used during the coronavirus pandemic by several businesses to provide COVID-19 testing services for their staff. This is enabling them to bring back those who may be self-isolating due to concerns over infection or that of a family member. It also allows laboratories to test for COVID-19 and influenza from a single sample, which will be incredibly beneficial as the Flu season approaches.
References:
- [1] Alessio Lorusso et al. (2020). A “One-Health” approach for diagnosis and molecular characterization of SARS-CoV-2 in Italy. One Health, Volume 10, 2020, Article 100135. https://www.sciencedirect.com/science/article/pii/S2352771420300823?via%3Dihub
- [2] Rajan Dewar et al. (2020). Viral transportation in COVID-19 pandemic: Inactivated virus transportation should be implemented for safe transportation and handling at diagnostics laboratories. Archives of Pathology & Laboratory Medicine. In-Press. Early Online Release. https://doi.org/10.5858/arpa.2020-0175-LE
- [3] Stephen R. Welch et al. (2020). Inactivation analysis of SARS-CoV-2 by specimen transport media, nucleic acid extraction reagents, detergents and fixatives. bioRxiv – preprint paper. https://www.biorxiv.org/content/10.1101/2020.07.08.194613v1
