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[THREAD]
1/21
A piece of fake news has been gaining currency on WhatsApp and Hindi news channels (of course) that claims coronavirus was "created" in a Chinese lab.
This thread is my attempt to shatter that myth in layman language. Feel free to use it in your arguments.
1/21
A piece of fake news has been gaining currency on WhatsApp and Hindi news channels (of course) that claims coronavirus was "created" in a Chinese lab.
This thread is my attempt to shatter that myth in layman language. Feel free to use it in your arguments.
2/21
Let's kill a most fundamental myth first: Coronavirus isn't something new and we've all had it at some point in the past. That's because corona isn't one virus but a family thereof that includes:
Common flu virus,
SARS virus,
MERS virus,
And some others.
Let's kill a most fundamental myth first: Coronavirus isn't something new and we've all had it at some point in the past. That's because corona isn't one virus but a family thereof that includes:
Common flu virus,
SARS virus,
MERS virus,
And some others.
3/21
Yes, the flu you get each year is a coronavirus disease! Here's some of the most widely known human coronaviruses and what they do:
HCoV-OC43 — Common cold
MERS-CoV — MERS
SARS-CoV — SARS
SARS-CoV-2 — COVID-19
See why we call the last one "novel coronavirus"?
Yes, the flu you get each year is a coronavirus disease! Here's some of the most widely known human coronaviruses and what they do:
HCoV-OC43 — Common cold
MERS-CoV — MERS
SARS-CoV — SARS
SARS-CoV-2 — COVID-19
See why we call the last one "novel coronavirus"?
4/21
The most recent common ancestor or MRCA of all human coronaviruses has been traced back to the 1950s according to a 2011 study published in the American Society of Microbiology's Journal of Virology. For the non-human variant, it goes back to 8000 BC. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3194943/
The most recent common ancestor or MRCA of all human coronaviruses has been traced back to the 1950s according to a 2011 study published in the American Society of Microbiology's Journal of Virology. For the non-human variant, it goes back to 8000 BC. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3194943/
5/21
So how do we know that evolved and not crafted in a petri dish? Let's understand its anatomy first:
A coronavirus is a single strand of RNA encapsulated inside a lipid casing lined with protein. This casing is covered in spikes made of a special kind of protein.
So how do we know that evolved and not crafted in a petri dish? Let's understand its anatomy first:
A coronavirus is a single strand of RNA encapsulated inside a lipid casing lined with protein. This casing is covered in spikes made of a special kind of protein.
6/21
The scientific name for these "spikes" is "receptor-binding domain" or RBD. Cells, on the other hand, have something called "receptors" scattered all over their outer membrane. Think of this as a velcro system. The RBD is the loopy side, the receptors are the fuzzy side.
The scientific name for these "spikes" is "receptor-binding domain" or RBD. Cells, on the other hand, have something called "receptors" scattered all over their outer membrane. Think of this as a velcro system. The RBD is the loopy side, the receptors are the fuzzy side.
7/21
This velcro system must work perfectly in order for the virus to be able to enter a particular cell. Think of it as a password if you will. Since the human coronavirus' RBD binds perfectly with human cells, it manages to infect us without any problem.
This velcro system must work perfectly in order for the virus to be able to enter a particular cell. Think of it as a password if you will. Since the human coronavirus' RBD binds perfectly with human cells, it manages to infect us without any problem.
8/21
Now that we understand how the velcro works, here's something we ought to know: The SARS-CoV-2 spikes don't mind with every human cells. The receptor they do bond with is the "angiotensin converting enzyme 2" (ACE2) which is only found on some very specific cells.
Now that we understand how the velcro works, here's something we ought to know: The SARS-CoV-2 spikes don't mind with every human cells. The receptor they do bond with is the "angiotensin converting enzyme 2" (ACE2) which is only found on some very specific cells.
9/21
These cells line up our lungs, arteries, heart, kidney, and intestines. ACE2 exists to keep our blood pressure in check via some complex biochemistry outside of this conversation. The fact that SARS-CoV-2 spikes bind so well and so exclusively with ACE2 is key.
These cells line up our lungs, arteries, heart, kidney, and intestines. ACE2 exists to keep our blood pressure in check via some complex biochemistry outside of this conversation. The fact that SARS-CoV-2 spikes bind so well and so exclusively with ACE2 is key.
10/21
This binding efficiency is the first evidence indicating natural selection (evolution) over genetic engineering (lab creation).
The other super to natural selection comes from the virus' backbone. Backbone is nothing but the virion's overall molecular structure.
This binding efficiency is the first evidence indicating natural selection (evolution) over genetic engineering (lab creation).
The other super to natural selection comes from the virus' backbone. Backbone is nothing but the virion's overall molecular structure.
11/21
If one were to "synthesize" a pathogenic virus, they'd start with the backbone of another virus from the same family, i.e. other coronaviruses. However, the backbone of this bad boy was established to be very different from those of both SARS and MERS viruses.
If one were to "synthesize" a pathogenic virus, they'd start with the backbone of another virus from the same family, i.e. other coronaviruses. However, the backbone of this bad boy was established to be very different from those of both SARS and MERS viruses.
12/21
In fact the SARS-CoV-2 backbone resembles those of coronaviruses found on bats and pangolins! This could mean only one thing. That the novel coronavirus evolved from bat coronavirus or pangolin coronavirus, independently of other human coronaviruses.
In fact the SARS-CoV-2 backbone resembles those of coronaviruses found on bats and pangolins! This could mean only one thing. That the novel coronavirus evolved from bat coronavirus or pangolin coronavirus, independently of other human coronaviruses.
13/21
That doesn't make sense in a laboratory. But it does in the natural world where mutations are numerous, constant, and uncontrolled. Remember, these are RNA viruses with no anti-mutation mechanisms built in.
With that firmly established, let's look at the possible pathways.
That doesn't make sense in a laboratory. But it does in the natural world where mutations are numerous, constant, and uncontrolled. Remember, these are RNA viruses with no anti-mutation mechanisms built in.
With that firmly established, let's look at the possible pathways.
14/21
Most researchers agree that the virus originated in a non-human cell, most likely bats, just as civets for SARS and camels for MERS. Why bats? Because SARS-CoV-2 resembles bat coronavirus the most. More than any other. That's why bats are the "villains" of this story.
Most researchers agree that the virus originated in a non-human cell, most likely bats, just as civets for SARS and camels for MERS. Why bats? Because SARS-CoV-2 resembles bat coronavirus the most. More than any other. That's why bats are the "villains" of this story.
15/21
But no bat-to-human transmission has ever been recorded. And since bat coronavirus cannot bind with human cells, two possibilities emerge from here:
One, the virus mutated to its ACE2-friendly form inside of the bat before entering humans via an intermediary like pangolin.
But no bat-to-human transmission has ever been recorded. And since bat coronavirus cannot bind with human cells, two possibilities emerge from here:
One, the virus mutated to its ACE2-friendly form inside of the bat before entering humans via an intermediary like pangolin.
16/21
The other possibility is that the non-pathogenic version entered humans unevolved and then mutated to its current form after a while. Inside unwitting humans.
This scenario finds support in the fact that the pangolin CoV has an RBD very similar to that of SARS-CoV-2.
The other possibility is that the non-pathogenic version entered humans unevolved and then mutated to its current form after a while. Inside unwitting humans.
This scenario finds support in the fact that the pangolin CoV has an RBD very similar to that of SARS-CoV-2.
17/21
So it's quite possible that the virus jumped from bats to pangolins to maybe civets or ferrets to humans, in the non-pathogenic form, and THEN mutated into the current form inside those human carriers via limited undetected circulation.
So it's quite possible that the virus jumped from bats to pangolins to maybe civets or ferrets to humans, in the non-pathogenic form, and THEN mutated into the current form inside those human carriers via limited undetected circulation.
18/21
Right now it's hard to tell which of the two scenarios are real, BUT there's little doubt one of them is. No third scenario exists, not even theoretically. Establishing which of these two is true, though, is critical. Here's why...
Right now it's hard to tell which of the two scenarios are real, BUT there's little doubt one of them is. No third scenario exists, not even theoretically. Establishing which of these two is true, though, is critical. Here's why...
19/21
If the first scenario is true and the virus evolved BEFORE entering human population, chances of recurrent future outbreaks are very real. That's because pathogenic strains must be then circulating in the animal kingdom as we speak. And mutating unhinged.
If the first scenario is true and the virus evolved BEFORE entering human population, chances of recurrent future outbreaks are very real. That's because pathogenic strains must be then circulating in the animal kingdom as we speak. And mutating unhinged.
20/21
If, however, it's the second scenario and the virus evolved AFTER entering human population, chances of recurrence are relatively lower. Note that I say RELATIVELY lower and not absolutely or zero and that's because viruses are still mutating, even within us.
If, however, it's the second scenario and the virus evolved AFTER entering human population, chances of recurrence are relatively lower. Note that I say RELATIVELY lower and not absolutely or zero and that's because viruses are still mutating, even within us.
21/21
So to conclude, no, the novel coronavirus is NOT a result of some "Chinese conspiracy gone horribly wrong." It's as natural as you and your friends and your food.
Here's the study referenced in this thread:
https://www.scripps.edu/news-and-events/press-room/2020/20200317-andersen-covid-19-coronavirus.html
So to conclude, no, the novel coronavirus is NOT a result of some "Chinese conspiracy gone horribly wrong." It's as natural as you and your friends and your food.
Here's the study referenced in this thread:
https://www.scripps.edu/news-and-events/press-room/2020/20200317-andersen-covid-19-coronavirus.html
