From friend and colleague, Heather DeVries, Indiana University Health: Hi, George. As I am sure you are aware, we are seeing some very high dimers now surrounding the COVID-19 pandemic.
An email was sent from one of our sites to the entire system that they may want to save those samples for future validation studies (truly high samples are hard to come by with IL’s high specificity assay). But then someone else responded to ask me if we really should be saving possible COVID samples. I see both sides, given universal precautions. Do you have any thoughts on this? If the virus is fairly susceptible to common cleaning agents, what happens to it with freezing at -20?
From Geo: Hi, Heather, I’m hoping we get ahead of the pandemic soon, and I’m encouraged by the number of high-volume and POC assays now available. I’m also struck by the connection between the virus and the sepsis-shock-DIC progression as described by Tang et al. that we posted on March 23. To get a first-hand answer, I reached out to two virology expert colleagues. Here are their answers:
From Rodney Rohde, PhD, Texas State University. Hi George, Typically viruses are stored for long term at -20 or -70C. I’m not thinking they would necessarily be inactivated. I used to place them at those temps or in liquid nitrogen for long term storage. YOU DO have to carefully freeze or thaw them so that there is no crystallization fracture to the virus which can inactivate it. Viruses are killed or destroyed better by heat than by cold and they need moisture to survive. This is why viruses stay contagious longer on nonporous metal and plastic surfaces than on porous items like soft toys, cloth, and wood. I hope this helps. Be safe!
And from Perry Scanlan, PhD, Austin Peay State University. As an enveloped virus you should not freeze it at -20C. This can form ice crystals which can damage viral envelopes. In this case I would freeze at -80C and avoid repeat freezing and thawing. I certainly would label these specimens as potentially containing SARS-COV-2. I do believe that these specimens could be useful for scientific study post pandemic. Freezing the samples and appropriately separating them in proper double containers should not pose a risk until those samples might be unfrozen at a later date. I might consider freezing virus from respiratory samples and serum or plasma as this could provide additional information about antibody formation and other important information.
My virologist friends are thinking primarily of preserving the virus, whereas you may be thinking of lab scientist safety. I don’t know of a way to first inactivate the virus before freezing without destroying or altering the hemostasis parameters. While they both hint the viruses may be destroyed by crystal formation, it seems there is no 100% guarantee.
From Ali Sadeghi-Khomami, Precision BioLogic: Hi George, There are many general techniques to inactivate viruses in plasma products that have already been applied to FFP. These techniques yet need to be validated for the inactivation of SARS-COV-2 as well as their compatibility with the downstream application of treated plasma samples. For instance, nanofiltration devices, detergent treatment, ethanol precipitation, pasteurization, etc. I think the most compatible and cost-effective technique that might inactivate single-strand RNA coronavirus but preserve coagulation factors would be UVC (254 nm) radiation. For further reading on this topic see Photochem Photobiol. 1997 Mar;65(3):432-5. Or if you need the product visit https://www.theraflex-uv-platelets.com/a-technology-based-purely-on-light/
Thanks so much for
Thanks so much for investigating this, George! You are correct that I was thinking from the perspective of lab safety. I also reached out to one of our clinical microbiologists about this. He indicated that our typical universal precautions (used properly) would be sufficient–lab coat, gloves, and face shield, and to avoid aerosol-generating procedures (vortexing an open tube). Between that and your information, there is much to consider.