Covid-19 Attack – Part 1

I have been asked by a couple readers to try and simply explain how the SARS CoV 2 virus enters humans leading to such a deadly assault on the body. The problem in doing such a blog is that the material is quite complex. Most of those out there reading do not have a strong understanding of cell biology, immunology and pulmonary function. But I am willing to try and present this on a level most can understand. If you are strong in biology and medicine there are plenty of papers out there with the complex details. My hope is to present this in a way most can understand.

So today starts a three part series which will look first at how the virus hijacks lung cells. Part Two will look at how the virus turns our immune system against us. Finally in Part Three, we will look at how Covid-19 is being treated, along with what the future may hold.

So today we look at how the virus enters the body through a single type of cell in our lungs and makes that cell produce thousands of copies of the virus. Those copies then invade more cells in the body with plenty left to spread to others we come in contact with. The figure below, Figure 1, will be our road-map through this complex subject. Each heading refers to one of the numbered locations on the figure. If my explanation seems to simple for you, great! I am not looking to talk down to anyone, just ensure as many as possible can understand what is a complex process.

So, here we go…

Figure 1Courtesy ChemistryViews

Point 1 – The Virus Arrives

Quite simply, the virus enters our body by either breathing it in or picking it up on our hands and touching our face, allowing the virus to enter the respiratory system. Once it enters the mouth or nose, the virus works its way down our trachea and into our lungs. Its target is the small air sacs in our lungs where we exchange oxygen and carbon dioxide. These are called the alveoli and they are where the virus really stakes it claim.

Figure 2 – Alveloi and their components

As seen in Figure 2, alveoli are basically small balloons, held open by surface tension, the same physical property which makes water bead into a ball on a solid surface. These small balloons are surrounded by tiny blood vessels known as capillaries, which are so small that blood cells and such have to move through one by one. These capillaries are where the smallest veins and arteries come together in the lung.

Back to Figure 2, we see that there are three types of cells which make up the alveoli and yes they have strange names. Let’s simplify it a bit. The Type I Pneumocytes are the gas carriers; Type II Pneumocytes, which produce something called surfactant, keep the balloon from collapsing; and those Alveolar Macrophages, are simply trash collectors and will be more important in Part Two of this series.

It is the Type II Pneumocyte that we care about. They produce a substance which keeps the balloon inflated, a vital function of breathing. Unfortunately, these cells have to be able to bring in certain chemicals to work properly. This is done by something called an ACE2 receptor. Just understand this as being a door to the cell. Now that door has a lock and only a perfectly matched key can open the door.

Let’s stop for a moment and look at the virus. Think of it as an egg with tiny three types of keys on the surface. The egg shell is the capsule which keeps the outside world from damaging the virus. The white of egg is the protein layer which protects the strand of genetic material in the yolk of the egg. Finally, one of the three types of keys, known as the “S Spikes” on the virus, are perfectly matched keys to the lock on the ACE2 door of the Type 2 pneumocyte cell.

When that key perfectly mates with the ACE2 receptor lock, a door opens and the whole virus is pulled into the inside of the cell. It is now in a position to take over the cell and make it stop producing surfactant and instead start making thousands of copies of the SARS CoV 2 virus to infect other cells and people.

Point 2 – New Instructions

With the virus now in the cell, it can begin executing its sole purpose for existing, to multiply. This begins by the egg shell capsule of the virus dissolving along with egg white, the protective protein layer. Now the most important part of the virus can go to work. This is a small strand of genetic material, similar to what makes up our chromosomes and genes, but smaller. It is much smaller than most of the single genes in the human body and we have over 20,000 such genes in the body. Think of this strip of genetic material as a detailed instruction manual on how to make new virus particles.

Point 3 – Cranking Up Production

Once in the fluid on the inside of the, this instruction manual is run through a structure in the cell called a ribosome, a sort of cell computer. First, this cell computer produces a few copies of the full instruction manual, just in case. Then the original copy of the detailed instruction manual is run through this computer again, where each individual chapter, which details how to produce one specific part of the virus, is split off.

Point 4 – Dividing the Task

Now we have a set of instructions telling the cell how to produce each part of the virus. One set details how to make several interlocking sections which will make up the capsule, our egg shell. Another details how to produce the inner protein layer, the egg white. Finally, a chapter details how to produce the three types of spikes, our keys. All the structural components of the virus now have recipes. So the cell computer begins doing just that, making the cell produce the raw materials needed to make many new viruses. These mega-materials are known as polyproteins.

Point 5 – Production Begins

While these polyproteins have all the ingredients needed to make the viral components, they are all packed together in huge bundles and need to be broken down into smaller units so the actual components can be built. Basically, they are creating and stockpiling all of the parts needed needed to build the components of the new viruses

Point 6 – Building Virus Parts

Using the numerous parts stockpiled in the past step, the virus now begins to use cellular machinery to build thousands of copies of the building blocks. If you remember any high school or college biology, we are talking about the endoplasmic reticulum and golgi bodies. For our purposes they are the cells factories. These factories begin to crank out thousands of virus parts which are going to be put together down the road. There might be three or four pieces of the capsule, egg shell, which can perfectly come together to form a complete sphere. The same goes for the protein protective layer, the egg white, which lines the inside of the capsule and protects the genetic material. The completely formed protein spikes, our keys, are ready to attach to the capsule, or egg shell, when assembly begins.

Point 7 – Making New Manuals

While the cell has been busily building pieces of the physical structure of new viruses, it was not forgotten that each of these shells has to have its own instruction manual in the form of identical strands of RNA genetic material. So all the while, the cells’ genetic coding section has been making copy after copy of the instruction manual, so one can be inserted in each new virus assembled.

Point 8 – Assembly and Packaging

With all the parts at the ready, those strangely named endoplasmic reticulum and golgi bodies, our cell factories, begin to take the parts and build copies of the virus by the thousands. Brand new, fully functional, virus particles are now just floating in little pockets of the cell, known as vesicles.

Point 9 – New Virus Particles

The new viral particles, floating within the cell, exit in one of two ways. First, the cell can expel the vesicles into the alveoli or capillaries in a manner no unlike taking out the garbage. Its technically called exocytosis. Just think of it as the virus putting out the trash. The cell can release a large number of the virus over time via this process. In addition, viral growth sometimes reaches such as level that the cell just can’t hold all of the copies and it bursts, dumping all of the new viral particles at once into the alveoli and bloodstream.

These brand new virus clones are now free to infect nearby cells and set up new production factories, whose entire purpose is to make more viral particles, which make more virus particles … Well you get the picture. If there are no more cells to attach to, around day 2 of the infection, the viral particles begin to be exhaled via breathing, coughs, and/or sneezes. They can also be passed on via contact with unwashed hands covered in virus particles. The virus can hang around in the environment for days just waiting for a new human host to come along and provide it a new breeding factory where the process begins again.

On to Part 2 …

In the next blog, we will look at how the virus causes illness in the body once it has gained a reproductive foothold there. Contrary to what many think, the virus does not produce any toxin or such which causes illness and damage. The progression of Covid-19 is merely the virus reproducing and how our own body attempts to fight off the assault.

REMEMBER: ONLY WE CAN STOP THE SPREAD OF COVID-19. NOT THE GOVERNMENT OR DOCTORS.

JUST ALL OF US FOLLOWING THE GUIDELINES TO THE LETTER. ANYTHING SHORT OF THAT WILL CAUSE MORE PEOPLE TO DIE. SIMPLE MATH TELLS US EVENTUALLY IT WILL BE SOMEONE YOU KNOW AND CARE FOR!

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