37 Trillion-
A human body has over 37 trillion cells! The number 37 trillion is a bit difficult to measure. It’s like 37 million million! Among these cells, there are different specialists cells each with. different assignments. Defense cells, muscle cells etc.
And a virus? It doesn’t even have one full-fledged cell! It whole body doesn’t have all the components and functions that is needed to make a cell!
Yet time and again these tiny less of a cell wages war against a human body of 37 trillion cells and totally beats it! Ask someone who made it out alive after being attacked by this 100 nM size. SARS-COV-2. Ask them how much this tiny submicroscopic particle made them suffer!
A four layer defense perimeter-
Us the. humans have four-layer impenetrable defense system! Yet, we totally get beaten by this damn virus! How come? What the virus has in it?
First two layers of four layers of defense are made of Barrier and Intrinsic immunity. This SARS-COV-2 virus beats this two barrier in one smart knock!
The invisibility cloak-
This novel coronavirus seems to have a unique ability, which it’s SARS-1 and MERS cousins did not have, to use one of our own enzymes named Furin. This virus uses this Furin thing to enter the cell in a stealth fashion and Furin yields the virus the invisibility cloak against first two layers is our defense system. This cunning ploy- with one invisibility cloak- helps overcome two of the four layers of our defense system.
The first breach-
When it enters the cell, most probably a cell in our nose or throat or intestine, this virus goes to work. It enters the ribosomes of the endoplasmic reticulum, the manufacturing plant of our cells and like a computer virus takes over its function. Next few days this lone coronavirus spends busy time relentlessly making parts of more coronaviruses. Once enough parts for new coronaviruses are made, this. virus uses our cell’s own assembly line to assemble a bunch of new viruses, the clone army! Once the clone army of the virus is made in the cell — it’s breaks the cell wall gets out of the cell, ready to march on to attack more cells.
The Trojan horse-
And finally, at this point, our immune system wakes up! intrinsic and innate immune system gets to work. A war starts between our intrinsic and innate defense systems and the clone army of marching viruses. More and more cells are being attacked and more and more batches of clone army are coming out to join the marching viruses. They go on to attack. cells of our brain, lung, intestines, heart, kidney or even pancreas.
The irked interferon-
One of the first weapons our intrinsic and adoptive immune system deploys is a signal molecule called Interferon! Suddenly waking up from slumber and seeing the marching clone army of viruses, this interferon goes to overdrive. Like a fire alarm system going off erratically — this interferon overreacts.
You feel the chill, fever or a little headache? It’s the effect of a little over abundance of this interferon. But until. this baffled interferon get it acts together — your fever Keeps raging!
The innate immunity-
In addition to interferon, other first line defense troops. come to scene quickly. Dendritic cells, neutrophils, ‘natural killer’ cells! Fierce battle ensues!
It’s seems in many people initially the viruses seems to be winning! The virus marches on — gets into the lung and kills. a lots of cells — dead cells, toxins — all create a situation called pneumonia!
On the other side of the war, from interferon — a more disciplined signal corps takes over! The cytokines!
The signal corps-
While some cytokines like IL-10, IL-4, TGF- beta tries to suppress the fire created by interferon, Cytokine molecules like IL-1, IL-6 and IL-12 starts sending signals to recruit more defense force units!
Did you ever wonder why I have whole body pain after viral infections? Why I feels so devastatingly lethargic? Or why I am so tired and sleepy? Don’t blame the viruses for that. These all are the direct effect of the cytokines released in response to viruses!
The elite forces-
As the battle rages, Innate immune systems dendritic cell units capture some virus and carries them to our lymph nodes. The lymph nodes are our defense manufacturing industry! Captured coronavirus are analyzed here and custom made attack forces are built and trained to fight the attackers — the coronaviruses! This custom made and trained forces are our body’s. antibodies and memory T-cells, specifically designed to fight the specific coronavirus! This is the final fourth layer of defense — the elite Adaptive immunity! For all the steps to complete and elite force to train against the attacker virus, it takes 5 — 7 days!
Didn’t we hear it somewhere that. antibody doesn’t appease before 5–7 days! Now you probably know why it is that!
The victory –
Once the elite forces of antibody and T cells take over, in most cases these coronaviruses have no chance. War ravages for a few more days but virus side keeps losing! In the war between human body and virus- the human body wins. Most people get better at this point.
Those who doesn’t get better — it means that virus keeps winning the battles!
And if you are the one who got better from the virus infection, you have these antibody and memory T-cells against the virus in your blood plasma. If you can donate some of this plasma to a sick person, it really helps him fight the virus!
The Achilles Hill –
But the elite adaptive immunity isn’t as strong in some! Esp people who are older, who has diabetes, High blood pressure, obese — they can’t afford a strong adaptive immunity- hence many human. loses the battle against the virus! Virus wins over!
The judgement day-
Apart from the above, in many cases — it’s not the virus that kills us! As the baffled interferon went into overdrive, in some patients the. signal transduction system called Cytokines also can’t act in a disciples fashion and gets hyper excited and goes erratic. As a result of these signals, our body’s own defense forces starts attacking us indiscriminately! Remember the judgement day in terminator movie? Like that movie, our signaling system drives into a rogue hyperdrive and starts signaling indiscriminate nuclear bombing! You have heard the term. Cytokine storm? Exactly This phenomenon has been described at the cytokine storm!
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Einstein once advised, ‘Everything should be made as. simple as possible, but no simpler’. I hope I haven’t ventured into the territory of beyond comprehensible simplicity.
Our discussion of humans and viruses will continue.
