(On this page in
Dutch I
post daily bits of realistic but hopeful Corona news. Here is a somehat
rough translation of an article on our immune system I posted there, because I
think it might also be useful for people that don’t speak Dutch).
COVID-19 can only live thanks to us. Viruses cannot reproduce
independently, they need our help. And our immune system makes this very
hard, as aptly explained in this excellent xkcd comic:
source
Before we continue, it is good to realize that our immune system appears to
be >99% effective against COVID-19, perhaps 99.9%: “three nines” as we
call it on the internet. It could be even better, we don’t know how many
people just never got sick at all because their immune system was there in
time. Hopefully the RIVM (Dutch CDC)
PIENTER
research and the tests at Sanquin (the Dutch blood
bank)
will tell us this soon.
Note: although I know a lot about DNA, the immune system is also new to
me. Normally I don’t write about topics that I don’t understand very
well, but these are execeptional times. If you are an expert or know one, can
you ask them to read this article critically and tell me what’s wrong at
bert@hubertnet.nl? Then I can quickly fix any errors. I am also aware that I
have skipped over many nuances in my description, but I am most concerned with
whether there are concrete untruths in what follows. Thanks!
Imagine a flashy spaceship lands in your backyard. The door opens and you
are invited to investigate everything to see what you can learn. The
technology is clearly millions of years beyond what we can make.
This is biology. That’s why it fascinates me so much. Life is billions of
years old technology, and we can explore it to see how it works!
Take me to your leader
Almost everything that we as humans have ever thought of existed in
nature for millions of years already: information storage, complete chemical
factories, signal processing, image processing, measurement and control
technology, artificial intelligence (but then the real thing). And
invariably we discover that the technology of nature is many times more
powerful than what we ever invented as humans.
To give a concrete example, even in 2020 we are unable to recognize proteins
quickly with technology that we have invented ‘as humans’. To do so, we
put the protein in a rabbit,
wait a while, and then we use the antibodies that the bunny made for us. We
can then make tests for that protein with those rabbit antibodies. We can’t
get there without nature’s help.
Our immune system is really unbelievably clever and far beyond anything we
can do with human hands. Unfortunately, we do not receive reports from our
defenses Last month 100.0% of all bacteria and viruses were kept out! We
should maybe appreciate it a bit more.
So why does it sometimes go wrong? Unfortunately, it seems that our immune
system occasionally goes off target and is overly active in the wrong place.
There are drugs that can dampen that, and much hope rests in those medicines
to cure seriously ill COVID-19 patients.
A few months ago, or as it feels, thousand of years ago, we thought that
bacterial anti-biotic resistance was the biggest threat to our health.
Bacteria evolve so fast, developing medicines seems hopeless.
But as it turns out, human beings have similarly powerful resistance
mechanisms – for every communicable disease that comes along, we develop
resistance in a week or two. And often subsequently remain immune
throughout our lives.
How do we do that? Bacteria evolve directly, but it turns out that our body has
its own evolution laboratory. The idea is as simple as it is brilliant. In
a previous Corona Update, I
described how antibodies “stick” to antigens (such as virus components).
After sticking, the virus is either disabled immediately or auxiliary troops
arrive which then destroy the virus.
In our body, antibody factories circulate, created randomly before we were
born. The antibodies produced have been filtered to not stick to ourselves,
but there is a good chance they will stick at least somewhat to everything else.
Each antibody is made by its own factory, the so-called B cells, also
known as white blood cells. Each B cell only makes 1 type of antibody.
As soon as our body detects it is being damaged, and an infection is
apparently going on, our immune system goes into top gear. And now comes the smart
bit. DNA can be called “the source code of
life” without exaggeration. (I
was fortunate enough to present about this at SHA-2017 for two hours, video &
slides )
Each B cell makes only 1 type of antibody, and the description of that
antibody is contained in the DNA of that B cell. Note that normally all our
cells have the same DNA, but B cells are allowed to change their genome.
And this turns out to be a good idea.
The DNA source code of the antibody in the B-cell is used twice:
- To make antibodies for export to the blood, to kill viruses etc.
- To attach antibodies to the outside of the B-cell (the factory)
And here’s how it works. A new virus, say COVID-19, circulates in our body
and causes damage. Our body fires up the immune system, but there is still
nothing specific to attack COVID-19. But due to the overwhelming amount of
random antibody designs generated earlier, there is probably one that one
will stick to the virus, if only a little bit.
Sometimes COVID-19 will now get stuck on a B-cell, because it also has antibodies on
its outside. Apparently there is a (weak) match between this antibody and
the virus. The B cell senses that it is occupied and then receives the
command: CLONE AND MUTATE.
Source
Normally, our body makes virtually no mistakes when copying DNA, but B-cells
are an exception to that rule: the DNA for the antibody gets copied with an error rate up
to 1 million times higher than normal. In addition, this DNA is also creatively
scrambled, rearranged, many things are
possible.
The occupied B-cell now clones itself, but the offspring is different
from the original. Maybe the antibody works a little bit better now, but
often it will be worse.
If it is an improvement, the copy will have a greater chance of sticking
to a COVID-19 particle again. And this improved copy now restarts the
process: DIVIDE AND MUTATE. And so on, and so on.
In this way, within a few days a B-cell evolves which is a factory for
antibodies that fit the virus perfectly. And because these well-functioning
B-cells are allowed to continue to copy, a strong flow of antibodies is
instigated.
These B-cells then remain active for as long as necessary, but over time
they ‘fall asleep’, ready to fight a new infection quickly should it come
back. This is then our long-term immunity.
The central trick that the B-cell antibody factories themselves also cling
to the virus, and thus get the command to mutate and share, is really
unbelievably clever.
No matter how dark things seem now – our immune system is incredibly
effective. With any luck, we will quickly find treatments for those tragic
cases where our immune system was not fast or good enough.
Please stay tuned for further updates!read more
