The use of denaturing solution as collection and transport media to improve SARS-CoV-2 RNA detection and reduce infection of laboratory personnel

Abstract

Accurate testing to detect SARS-CoV-2 RNA is key to counteract the virus spread. Nonetheless, the number of diagnostic laboratories able to perform qPCR tests is limited, particularly in developing countries. We describe the use of a virusinactivating, denaturing solution (DS) to decrease virus infectivity in clinical specimens without affecting RNA integrity. Swab samples were collected from infected patients and from laboratory personnel using a commercially available viral transport solution and the in-house DS. Samples were tested by RT-qPCR, and exposure to infective viruses was also accessed by ELISA. The DS used did not interfere with viral genome detection and was able to maintain RNA integrity for up to 16 days at room temperature. Furthermore, virus loaded onto DS were inactivated, as attested by attempts to grow SARS-CoV-2 in cell monolayers after DS desalt filtration to remove toxic residues. The DS described here provides a strategy to maintain diagnostic accuracy and protects diagnostic laboratory personnel from accidental infection, as it has helped to protect our lab crew.

Analysis by real‐time PCR of five transport and conservation mediums of nasopharyngeal swab samples to COVID‐19 diagnosis in Santiago of Chile

“…21 The use of this viral stabilizing and inactivating agent has been widely used in the study of several viruses 22,23 including SARS-CoV-2 for their detection and diagnosis during the pandemic. 12,24,25 For example, Carvalho et al 26 analyzed NPSs kept in the medium with guanidine salts, obtaining Cq values like those reported in our current study. On the other hand, the PBS-preserved NPSs showed higher Cq values for internal reference RNase P probe than DNA/RNA Shield™, NAT, VTM-N, and Ezmedlab mediums.…”

Analysis of Four Different Transport and Preservation Medium Kits for Sars-Cov-2 Diagnosis From Nasopharyngeal Swab by Real-Time Pcr: Adapting to the Constantly Increasing Demand of Sampling Processing and Stock-Outs During the Pandemic

“…The use of this viral stabilizing and inactivating agent has been widely used in the study of several viruses [29,30] including SARS-CoV-2 for their detection and diagnosis during the pandemic [14,31,32]. For example, the Carvalho et al 2021 [33] analyzed NPSs kept in the medium with guanidine salts, obtaining Cq values like those reported in our current study. On the other hand, the PBS-preserved NPSs showed Cq values for RNase P higher than those obtained for DNA/RNA Shield™, NAT and even VTM solution in the case of a strategy following thermal inactivation and RNA extraction.…”

How to better select SARS‐CoV‐2 preservation solution of virus nucleic acid testing

“…These salts also have the ability to inhibit RNase 20 . Referring to GITC for chemical lysis of viruses, 13,18,21 we utilized guanidinium hydrochloride and GITC as virus preservation buffers and both of them demonstrated good preservation stability when used at appropriate concentrations. A concentration of 0.5 mol is not recommended for guanidine content as a viral preservation solution for NAT.…”

“…), ribonuclease inhibitors (e.g., diethylpyrocarbonate [DEPC], guanidine isothiocyanate, oxovanadate ribonucleoside complex, SDS, and urea, etc.) and buffer solution, so guanidine salt, alkaline ethylene glycol, EDTA, Tris buffer solution, and sodium citrate can be added 13,14 . IA allows long‐term transportation and storage at room temperature instead of cold chain transportation, which can save the costs of storage and transportation of virus samples.…”