Al Stahler: Battling a virus
Depending on your definition of life, the virus may or may not even be alive. But — alive or not — the COVID-19 virus is cunning.
Everything alive depends on machinery to keep us going. Take digestion.
Digestion is demolition — taking food apart. Every molecule — every tiniest particle — of table sugar, for instance, must be broken in two, before we can “burn” it for energy.
The machines that do the body’s work are enzymes.
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Just as a wrench must be the right size and shape to grasp the head of a bolt, the business-end of the sugar-busting enzyme – the enzyme’s “active site” – must be able to grasp the sugar molecule.
The enzyme’s active site and the sugar molecule are each shaped like pieces of a jigsaw puzzle. Not a flat puzzle, but a three-dimensional (3-D) jig-saw puzzle, in which the pieces bulge in and out, up-and-down, front-to-back, side-to-side.
Enzymes work in every part of our body — building up, tearing down, making repairs, generating energy — enzymes are everywhere, all with jigsaw puzzle active sites.
The organs in our bodies need to talk to each other. Our nervous system communicates with electricity, but most organs must put their messages down in writing.
It’s dark in there, inside our bodies, so reading and writing must be done by feel, by Braille, encoding messages into 3-D puzzle pieces.
Hormones are 3-D puzzle pieces. Thanks to their shapes, they carry their messages only to organs with matching pieces.
Sometimes, messages must be modified — made stronger or weaker, even shut down. Enzymes slice and dice the messages, changing their meaning, according to need.
A common challenge in plumbing is to balance the pressure in pipes: Pressure must be high enough to launder clothes and shower ourselves at the same time; but not so high that we blow out the pipes.
So, too, the plumbing in our bodies must be balanced: Blood pressure measured, signals sent, adjustments made. As conditions change, signals are modified by enzymes.
One such enzyme — with its own 3-D active site, for latching onto message-bearing puzzle-pieces — is ACE2.
When first studied, ACE2 was found mostly on the outer “skin” of cells in the gut, heart and kidneys. But later, ACE2 was found to reside, too, in the lungs.
Coronaviruses — such as the virus that causes COVID-19 — are so-called because they’re surrounded by spikes … spikes that — in electron micrographs — give the virus a crown — in Latin, a “corona.”
At the tips of these spikes are puzzle pieces — 3-D puzzle pieces that match up with the one in ACE2, allowing the virus to attach itself to the enzyme.
The outer “skin” of the virus is made of the same sort of stuff as the outer “skin” of the cell. The skins dissolve into each other, become one, and the virus slips into the cell. At which point the virus announces, “You are now working for me.”
Fortunately, roughly half a billion years ago, our ancestors — early members of the animal kingdom, before there were people or dinosaurs or reptiles or amphibians … back when the most advanced animals were fish — our ancestors demonstrated that two can play at this game.
The viral spikes are covered with their own 3-D puzzle pieces … and once our immune system spots those pieces of alien puzzle, it sends out puzzle pieces to match, to attach and mark the virus for destruction. These 3-D jig-saw attackers are antibodies.
Don’t get the wrong idea about the word “antibody” — just as astronomers refer to lots of things as “bodies” — planets, moons, comets are all celestial “bodies.” So, too, biologists refer to all sorts of tiny things as “bodies.” The antibody does not attack our body — it defends it.
Where did the COVID-19 virus come from? Assembling a jig-aw puzzle takes time and patience. It could be done faster … by finding pieces that sort of fit … and jamming them together.
All mammals share many of the same parts … but the puzzle pieces are just different enough that we cannot, say, transplant a sheep heart into a human. Nor, for the most part, can viruses from one species infect another.
Unless the puzzle pieces match close enough that they can be jammed together. The COVID-19 virus seems to have come from a bat. This would also explain how COVID-19, in a zoo back east, apparently “spilled-over” into a tiger.
If you’ve been exposed to a virus, and now carry antibodies to that virus, you might now be immune. Testing positive for antibodies to the COVID-19 virus might, in the near future, be a get-out-of-jail free card for folks no longer at risk of catching, nor spreading, the disease.
I asked virologist Tony Mazzulli (Microbiologist-in-Chief, Mt Sinai Hospital), whether the virus can remain infectious, after it dries out. Remember that, to get inside us, the viral membrane must merge with our own. But, as Dr. Mazzulli explains, the “membrane around it … will easily break down, once the surface/droplet dries. Since the viral attachment proteins [the 3-D puzzle pieces] are found on the surface of the envelope, once the envelope is destroyed, the virus is no longer infectious, as it will not be able to attach to a cell and be internalized.”
Conclusion: Maintain a “social distance;” wash hands; and, when social distance cannot be maintained, say, at the grocer’s, avoid spraying droplets on others by wearing a mask.
In the sky: Because of the geometry of Earth’s orbit — angles and such — the amount of time the sun remains just below the horizon — still lighting the sky, after it sets — changes though the year. The sun lingers least at the time of the equinox. Spring equinox occurred in late March, so twilight now is short: the sun goes down, and the sky grows dark.
Take care of yourself, take care of each other.
Al Stahler enjoys sharing science and nature with friends and neighbors on KVMR-FM, and can be reached at firstname.lastname@example.org.
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