Marc Veldhoen on BlueSky attempts to describe virus life-cycle, includes hijacking cell functions for replication

Steven Avery

Administrator
After 5 years in a pandemic caused by a #virus , there is misunderstanding and misinformation about what a virus actually is. Not incomprehensibly, the scientific community has also repeatedly changed its mind about what viruses are. A 🧵
Woman with mask


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December 9, 2024 at 2:25 PM
24 reposts
4 quotes
90 likes










‪Marc Veldhoen‬ ‪@marcveld.bsky.social‬
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1mo
#Viruses were seen as poisons and even chemicals. Now they are seen as something between living and non-living. Viruses cannot multiply by themselves, they need a living cell that they abuse for their own purposes.
Representation of a virus particle


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‪Marc Veldhoen‬ ‪@marcveld.bsky.social‬
·
1mo
Because viruses are something between life and non-life, they were often ignored and misunderstood. This is often still the case with non-experts. However, we now know that they are very important players in the general history of evolution and life.



‪Marc Veldhoen‬ ‪@marcveld.bsky.social‬
·
1mo
The first studies on viruses came through its association with disease. “Virus” comes from Latin and means; slimy liquid. The word was already used in the 17th century as a sickening liquid or poison. It remained that way until the 1950

‪Marc Veldhoen‬ ‪@marcveld.bsky.social‬
·
1mo
At the end of the 19th century, it was discovered that rabies and foot and mouth disease were caused by particles that resembled bacteria but were much smaller. They could be transferred from one host to another with obvious disease-causing effects (from mild symptoms to death).


‪Marc Veldhoen‬ ‪@marcveld.bsky.social‬
·
1mo
Experiments seemed to indicate that #viruses were a simple, but by no means easy, form of life. There are many different types of viruses, they vary a lot and often do not resemble each other. And yet in 1935 they were relegated to chemicals again.
depicting different shapes of viral particles, from classic to ball-shaped and a bacteriophage.


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‪Marc Veldhoen‬ ‪@marcveld.bsky.social‬
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1mo
Wendell M. Stanley and colleagues, (Rockefeller University, NY), crystallized tobacco mosaic virus. This was not at all like the cells that were already known at the time. It had molecules but no compartments (organelles), such as those present in the cells of plants or bacteria.

‪Marc Veldhoen‬ ‪@marcveld.bsky.social‬
·
1mo
Stanley even got the Nobel Prize (1946), not for medicine but for chemistry! With the discovery of DNA and then RNA (1950s and 1960s), it turns out that a #virus contains genetic material, unique to that virus and not present at all in the host or other life form.
Different viruses in a diagram, from RNA to DNA viruses.


ALT

·
1mo
A virus is therefore DNA or RNA, which is surrounded by a coat of protein or fat-membrane. These protect the genetic material while 1 or more proteins in the coat are required for entry into the host cell. A virus is completely dependent on that host cell and appears to be inactive.




·
1mo
However, when it enters the host cell, the virus sheds its coat and exposes the protected genetic code to the proteins in the host cell. They often treat the code just like their own code and get to work translating it into proteins. youtu.be/k2GlafQ9YhY

The lifecycle of SARS-CoV-2
YouTube video by Phospho Biomedical Animation


youtu.be

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