Evaluation of Commercially Available Viral Transport Medium (VTM) for SARS-CoV-2 Inactivation and Use in Point-of-Care (POC) Testing

Abstract

Critical to facilitating SARS-CoV-2 point-of-care (POC) testing is assurance that viruses present in specimens are inactivated onsite prior to processing. Here, we conducted experiments to determine the virucidal activity of commercially available Viral Transport Mediums (VTMs) to inactivate SARS-CoV-2. Independent testing methods for viral inactivation testing were applied, including a previously described World Health Organization (WHO) protocol, in addition to a buffer exchange method where the virus is physically separated from the VTM post exposure. The latter method enables sensitive detection of viral viability at higher viral titre when incubated with VTM. We demonstrate that VTM formulations, Primestore® Molecular Transport Medium (MTM) and COPAN eNAT™ completely inactivate high-titre SARS-CoV-2 virus (>1 × 107 copies/mL) and are compatible with POC processing. Furthermore, full viral inactivation was rapidly achieved in as little as 2 min of VTM exposure. We conclude that adding certain VTM formulations as a first step post specimen collection will render SARS-CoV-2 non-infectious for transport, or for further in-field POC molecular testing using rapid turnaround GeneXpert platforms or equivalent.

African Swine Fever Laboratory Diagnosis—Lessons Learned from Recent Animal Trials

“…The PrimeSwab and the accompanying PrimeStore MTM lived to our expectations and performed best in the comparison. This system has been evaluated using both bacterial and viral pathogens, including SARS-CoV-2 and is intriguing because of the safe inactivation of pathogens and preservation of nucleic acids [ 41 , 42 , 43 , 44 ]. Whether it is worth using this system or its sequels (PrimeStore HCP) instead of simple swab systems, remains the choice of users based on risk assessment, integration into strategies, and financial resources.…”

Inactivation of SARS-CoV-2 virus in saliva using a guanidium based transport medium suitable for RT-PCR diagnostic assays

“…The more rapid processing also ensured that we were able to make accurate determinations of buffer inactivation time. Dilution methods might have been an alternate way to remove cytotoxic components; however, we have observed that eNAT remained cytotoxic even after a 1000-fold dilution (data not shown) and such high dilutions can produce misleading estimates of log titer virus inactivation unless very high titer viral stocks can be tested [ 7 , 13 ].…”

“…Buffers and reagents containing guanidium hydrochloride and guanidinium thiocyanate have shown to inactivate SARS-CoV-2, and these reagents can be used for RT-PCR applications [ 5 , 9 , 11 , 12 ]. The eNAT (Copan Diagnostics, Murrieta, CA) is a guanidium thiocyanate based medium designed to be used for specimen collection and transport as it can stabilize nucleic acids for prolonged periods of time ( https://www.copanusa.com/sample-collection-transport-processing/enat/ ) [ 13 ]. In this study, we evaluated the effectiveness of this media for inactivating SARS-CoV-2 in cell culture supernatants and virus-spiked saliva matrix and its ability to be used to detect SARS-CoV-2 in the oint-of-care Xpert Xpress SARS-CoV-2 assay.…”

A decentralised point-of-care testing model to address inequities in the COVID-19 response

“…Each cartridge requires a testing kit consisting of a swab and viral transport medium, and any viral transport medium can be used. During the programme, we changed from using a universal viral transport medium to a molecular transport medium (Longhorn, TX, USA), which preserves the integrity of the RNA, 23 is useful for transport of specimens, and inactivates the virus, rendering the sample non-infectious, 24 thereby increasing POC test operator safety.…”