I’ve been pondering two questions.
1. What is least destructive way to kill coronavirus in vitro?
2. Which imported foods are responsible for international coronavirus transmission?
Coronavirus is a single stranded RNA (ssRNA) virus. The ideal “least destructive” method would be the destruction of ssRNA without losing the capsid integrity. Minimisation of vaccine side effects, and ease of purification are both optimised when the capsid stays intact. The next best option, easier, would be retaining the coat protein intact (no denaturisation or interaction) when other components are removed. That would be harder to purify and have more side effects, but would still work.
I was wondering whether both problems could be resolved by UHT treatment, but it appears not.
Papers about the chemical changes induced by UHT, such as “Improving UHT processing and UHT milk products” https://sci-hub.st/https://www.sciencedirect.com/science/article/pii/B9781845694388500131 don’t mention viruses at all, or RNA/DNA for that matter. Which is annoying. The dominant effect of UHT seems to be destroying the conformation of natural proteases, and killing thermophyllic spore-forming bacteria. Even there, they don’t explain which parts of the bacterial spore are attacked by the UHT.
Papers about the killing of viruses with heat, such as “Thermal inactivation of animal virus pathogens” http://www.researchtrends.net/tia/article_pdf.asp?in=0&vn=11&tid=38&aid=5378 The following are quotes from that.
“Lelie et al. compared the heat inactivation of twelve different virus families in reconstituted human serum (0.6% v/v) under two of the steps used for the manufacture of Hepatitis B vaccine. Heating at 65 °C for 15 min completely inactivated (> 4 log reduction) nine of the twelve selected virus families. Heating at 93 °C for 90 s inactivated 11 of the 12.”
“The most widely reported recent studies on the inactivation of viruses in food and the environment have focused on the survival of viruses in meat, dairy products, animal feed, waste and the environment.”
“Inactivation may proceed through degradation of the viral nucleic acid at low temperatures (< 40 °C) or destruction of the virus coat protein and receptor binding at higher temperatures”. “ionic strength also influences capsid stability”.
So low temperatures is what we want for least destructive in vitro killing (ie. simple vaccine production), with ionic strength chosen to maximise capsid stability. But either will do for stopping international transport by food, where we want to minimise capsid stability.