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Author: Subject: COVID-19 heat resistance ?
MadHatter
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[*] posted on 22-4-2020 at 21:00
COVID-19 heat resistance ?


Snippet from the website:

Researchers from the University of Aix-Marseille in France,
led by Remi Charrel and Boris Pastorino, found that the
virus survived in 140-degree Fahrenheit temperatures typically
used to disinfect research labs, The Jerusalem Post reported.

It took 15 minutes of exposure to 197.6-degree temperatures to
kill the virus, the newspaper noted, adding that the study had
yet to be peer-reviewed.


Link: https://thehill.com/policy/healthcare/493530-french-research...


WOW ! That's 14.4F below steam if there's any truth in it. I'm a
bit skeptical and I don't scare easily.

Could this be a prelude to so-called tougher "stay at home" directives ?

Any comments, speculation or thoughts are appreciated.

MODS: If this is in the wrong section, I apologize, and please move it.




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Tsjerk
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[*] posted on 22-4-2020 at 21:16


Quote: Originally posted by MadHatter  

Researchers from the University of Aix-Marseille in France,
led by Remi Charrel and Boris Pastorino, found that the
virus survived in 140-degree Fahrenheit temperatures typically
used to disinfect research labs.


Typical is 120 degrees Celsius for 20 minutes. That would kill the virus. Objects that can't be autoclaved, like benches and so are typically desinfected with 70% ethanol.

[Edited on 23-4-2020 by Tsjerk]
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unionised
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[*] posted on 23-4-2020 at 03:53


Quote: Originally posted by MadHatter  
140-degree Fahrenheit temperatures typically
used to disinfect research labs,



Where is that "typical"?
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solo
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[*] posted on 23-4-2020 at 06:33


"COVID-19 heat resistance".....


COVID-19 and food: ‘This virus is sensitive to cooking temperatures’

16-Mar-2020 By Flora Southey

French food agency ANSES says heat treatment can reduce contamination of a food product by a factor of 10,000.

https://www.foodnavigator.com/Article/2020/03/16/COVID-19-an...




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CharlieA
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[*] posted on 23-4-2020 at 16:17


Quote: Originally posted by Tsjerk  


Typical is 120 degrees Celsius for 20 minutes. That would kill the virus. ...

[Edited on 23-4-2020 by Tsjerk]


I have a very limited grasp of biochemistry, so please forgive me if I am completely missing the point, but I thought that viruses were not alive, and therefore cannot be killed...or is "killed" refer to some kind of deactivation?
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Gearhead_Shem_Tov
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[*] posted on 23-4-2020 at 17:38


Quote: Originally posted by CharlieA  
Quote: Originally posted by Tsjerk  


Typical is 120 degrees Celsius for 20 minutes. That would kill the virus. ...

[Edited on 23-4-2020 by Tsjerk]


I have a very limited grasp of biochemistry, so please forgive me if I am completely missing the point, but I thought that viruses were not alive, and therefore cannot be killed...or is "killed" refer to some kind of deactivation?


"Denatured" might perhaps be more accurate, but killed is close enough.
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mayko
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[*] posted on 23-4-2020 at 18:56


Quote: Originally posted by CharlieA  

but I thought that viruses were not alive,


This hits the deep question of "What is Life?", and as such is a great way to start a fistfight at a biology convention! My main takeaway has been mindfulness of the distinction between a virion (the infectious capsid particle containing the viral genome) and the virus itself (a phenomenon which spends part of its "life cycle" as a virion).


POINT: Viruses are alive

Raoult, D., & Forterre, P. (2008). Redefining viruses: lessons from Mimivirus. Nature Reviews. Microbiology, 6(4), 315–319. https://doi.org/10.1038/nrmicro1858

Attachment: Redefining virueses - lessons from mimivirus.pdf (925kB)
This file has been downloaded 100 times

Forterre, P. (2010). Defining life: the virus viewpoint. Origins of Life and Evolution of the Biosphere : The Journal of the International Society for the Study of the Origin of Life, 40(2), 151–160. https://doi.org/10.1007/s11084-010-9194-1

Attachment: Defining Life - the virus viewpoint.pdf (144kB)
This file has been downloaded 90 times

COUNTERPOINT: Viruses are not alive (and Forterre is wrong more generally)

Whittington, A. C., Mason, A. J., & Rokyta, D. R. (2017). A Robust ANOVA Approach to Estimating a Phylogeny from Multiple Genes. Molecular Biology and Evolution, 0(Ml), 1–18. https://doi.org/10.1093/molbev/mst

Attachment: Ten_reasons_to_exclude_viruses.pdf (363kB)
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Tsjerk
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[*] posted on 23-4-2020 at 21:58


In the strict definition of life, viruses are not alive as they don't show any metabolism. Until some time ago I would never have used the phrase "kill a virus", but with all the news about corona... I have capitulated.

Denatured is a term that could be used, but I would say inactived is more accurate, as you can take a virus apart without denaturing it.

But nowadays nobody except for crazy old biologist will haress you for saying "killed".
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[*] posted on 24-4-2020 at 01:18


If life is an operating system then a virus is a batch file.
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[*] posted on 24-4-2020 at 11:13


Sounds like the virus is resilient compared to others with respect to heat (IR).

A couple well written articles from the BBC on heat and UV denaturing coronavirus:
https://www.bbc.com/future/article/20200323-coronavirus-will...
https://www.bbc.com/future/article/20200327-can-you-kill-cor...

The "marked winter seasonality" hypothesis (mentioned in the hot weather article), that sunlight spectra may denature exposed viruses and reduce cases, makes sense.

I suppose metals may act as a catalyst for denaturing viral surface proteins, reducing the required temperature?

EDIT: Further, perhaps such a catalyst, in water or fat soluble molecule form, could enable body-temperature in-vivo denaturation of viral surface proteins? Delivered as aerosol to lungs.

[Edited on 24-4-2020 by andy1988]




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[*] posted on 25-4-2020 at 10:10


Quote: Originally posted by mayko  

Whittington, A. C., Mason, A. J., & Rokyta, D. R. (2017). A Robust ANOVA Approach to Estimating a Phylogeny from Multiple Genes. Molecular Biology and Evolution, 0(Ml), 1–18. https://doi.org/10.1093/molbev/mst



Sorry - I must have hit the wrong thing in Mendeley... this is actually

Moreira, D., & López-García, P. (2009). Ten reasons to exclude viruses from the tree of life. Nature Reviews Microbiology, 7(4), 306–311. https://doi.org/10.1038/nrmicro2108

It's certainly true that virions don't have a metabolism... but then again, tardigrade tuns and resting giardia spores aren't exactly hustling to turn free energy into heat, either! At the same time, if a virus doesn't have a metabolism, how does it produce more virions? What is the process of polymerizing nucleic acids, assembling a capsid, and packaging it with a genome, if not a metabolic one?

Usually the response is to claim that molecular machinery performing key steps in this process belong to the host cell. But to the extent that an enzyme is helping a virus reproduce (usually at great detriment to the cell), how can it be said to belong to the cell, and not the virus?

Typically what is meant is that those resources were produced from cell-sourced monomers, using cellular ATP, following a cellular genome, which the virus then came along and hijacked. But we have a word for an entity that goes around jacking other entities' processes: we call it a parasite. When such an entity cannot persist without doing so, we call it an obligate parasite. There are plenty of obligate parasites which are alive!

It might be true that viral parasitism is so trivial and so obligate that it makes sense to say it's not life, but I don't think that it's obvious that's true. Here's an example: after its morphology and developmental cycle were characterized, the infectious agent of parrot fever (psittacosis) was thought to be a virus for decades, due to its size and its extreme dependence on its host cells. It later turned out to be a very, very small Chlamydia bacterium. Are some bacteria not alive? (Moreira & López-García's answer is that while some bacteria are obligate parasites, all viruses are. Personally, I don't find that very satisfying.)


Quote: Originally posted by andy1988  

The "marked winter seasonality" hypothesis (mentioned in the hot weather article), that sunlight spectra may denature exposed viruses and reduce cases, makes sense.


I just saw a roundup the Berkeley Earth team on this.... their results were less than reassuring, finding little climatic signal when controlling for things like the geography of spread by considering growth rate or aligning regions by progress of epidemic, rather than a raw count time series.

http://berkeleyearth.org/coronavirus-and-the-weather/

Quote:

At this point in the pandemic, it has become clear that a warm climate, at least up to ~32 °C (90 °F) is not by itself sufficient to prevent local transmission of the coronavirus responsible for COVID-19. Sustained community transmission has already been observed in a variety of countries with warm climates.

Whether a warm or sunny climate might still have a mild effect on slowing transmission is unclear. Some of the above charts suggest that a mild effect is possible. However, the growth rates observed across a variety of climates do not show signs of a strong relationship or limitation across the range of weather conditions that have been observed so far.

One explanation may be that a majority of transmission simply occurs indoors during close interactions with family, friends, and coworkers. A Chinese contact tracing study looking at over 7000 cases with known routes of exposure identified only a single example where the virus was known to have spread during an outdoor contact. It is entirely possible that the lack of evidence of weather effects on the spread of COVID-19 reported above is primarily due to indoor spread under conditions that may be decoupled from the ambient weather.

Under these circumstances, it appears likely that COVID-19 will remain capable of significant spread during warm and sunny conditions, as already evidenced by the serious outbreaks in locations such as Ecuador and Brazil.



I thought it was interesting that they picked out UV flux as the most likely candidate for an impact; looking closely, I could believe that there's an effect in the tails of the flux distribution. But is it really that much clearer an effect than the one shown by absolute humidity? (in which it's the drier regions which have the higher growth rates!)




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clearly_not_atara
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[*] posted on 25-4-2020 at 10:59


Quote: Originally posted by Tsjerk  
In the strict definition of life, viruses are not alive as they don't show any metabolism. Until some time ago I would never have used the phrase "kill a virus", but with all the news about corona... I have capitulated.

The term "kill" does not always indicate life. You can kill a plan, a computer process, an engine, etc. Viruses do not need to be categorized as living so that we can say they were killed.




[Edited on 04-20-1969 by clearly_not_atara]
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