The COVID-19 pandemic has created an unprecedented need for diagnostic RT-PCR testing. The preferred sample type is commonly considered to be a nasopharyngeal (NP) swab specimen delivered to a molecular laboratory environment in a viral transport media (VTM). Previously, due to the widespread demand for SARS-CoV-2 RT-PCR testing, the COVID-19 pandemic has seriously interrupted the global supply of viral transport medium.
VTM is available in a variety of formulations, all of which include, a complex supply of protein and/or amino acids, a buffered salt solution, and antimicrobials. Its purpose is to store viruses for eventual amplification using NAAT technology and/or viral culture. While basic formulations, such as saline, are technically compatible with RT-PCR, the majority of NAAT assays for respiratory viruses have been produced and FDA-cleared for use with more sophisticated transport media (i.e., VTM and universal transport medium, UTM). Furthermore, virus stability in saline may not be desirable over time, resulting in the viral nucleic acid breakdown due to osmotic imbalance. This may alter the integrity of single-stranded RNAs; further compromising its detection through RT-PCR. Also, the formulations prepared for easy transportation of viral particles should contain an appropriate concentration of antibiotics as well as antimycotic to prevent entry and growth of unwanted pathogens that can in turn hamper the final diagnostic outcome. Thus, the Centre for Disease Control (CDC) has proposed standard guidelines to prepare versatile viral transport mediums for safe and easy transportation during pandemics.
Production of VTM
VTM production on a broad scale to support a hospital network demands a lot of equipment, such as reagent storage, bench space, and several biosafety cabinets. There should be proper in-house facilities for VTM production, unlike some companies that do not have appropriate facilities for the bulk production of VTM. In addition, specialized individuals with laboratory experience are needed at a time when technologists are needed to deal with increased demand for VTM and maintain its diagnostic effectiveness.
Sterility of the VTM
A sterile environment is essential for the production of VTM in order to prevent organisms from overgrowing the transport medium and interfering with the subsequent tests. Thus, It is always recommended to manufacture VTM in an aseptic environment with closed aliquoting systems to minimize human interface. It is also important to note that VTM should be free from nucleic acid contamination that may interfere with the final outcome.
Recovery of viral nucleic acid from VTM
The feasibility of nucleic acid retrieval from the test VTM is assessed across a wide range of analyte concentrations. It is important to determine the VTM for analyte concentrations at the detection limits of the assays performed. Moreover, stability studies should also be performed to assess the stability of VTM at room temperature and also at refrigerated temperature. Studies have proposed that on a generalized note VTM is stable at room temperature for 2 months and at refrigerated conditions for 2 years.
To properly understand why the growing list of COVID-19 vaccines or therapeutics fails, conservative maintenance of SARS-CoV-2 in patient samples is crucial.VTM preparation is important to protect the virus’s ability to replicate.
Throughout these unprecedented times, Advancells Group has consolidated the scientific experience and technological know-how to provide diagnostic solutions crucial for COVID-19 specimen collection, transport, storage, and diagnostic confirmation. Our Universal transport medium is a CE-marked transport system that is ideal for the collection, transportation, maintenance, and long-term storage of clinical specimens harboring a broad array of pathogenic organisms, including but not limited to COVID-19. The transport medium is delivered in a gamma sterilized, screw cap, conical-bottom centrifuge tube that is adequate to retain viability and molecular coherence for 48 hours after collection, also when transferred at ambient temperature. The CDC Interim Guidelines are met by our collection and transport kits.
For more details on VTM, contact us at [email protected]