CoronaVirus has become the number 1 enemy that the world is fighting of today and many cities are in lockdown due to this Virus, But how does it replicate in your body and cause Pneumonia? Let’s answer this question with the simplest approach
To understand how this works we need to understand the Molecular Biology of the cell First:
Consider a cell as shown in the figure, it has 2 parts Nucleus and Cytoplasm. Nucleus has a double-stranded ( the 2 waves that offset one another as shown in fig ) set of DNA (Deoxyribo Nucleic Acid). DNA is a long molecule that contains our unique genetic code. it is Like a recipe book, it holds the instructions for making all the proteins in our bodies. DNA contains four basic building blocks :adenine(A), cytosine(C), guanine(G) and thymine(T). The order of these building blocks forms the instructions in the Genome. Each strand of DNA has a beginning and an end called 5’(five prime) and 3’(three prime) respectively. The two strands run in the opposite direction (antiparallel) to each other so that one runs 5’ to 3’ and one runs 3’ to 5’, they are called the sense strand and the antisense strand, respectively. (This Understanding of DNA is very important to know how exactly this Virus work)
The next step in the process is that the Transcription (copying the genome ) of this DNA occurs into a single-stranded Molecule called RNA (Ribo Nucleic Acid), The newly formed RNA molecule leaves the Nucleus and moves to Cytoplasm, As this RNA is in cytoplasm it comes in contact with Ribosomes (indicated in green color) which moves from 5’(five prime) to 3’(three prime) and as it travels it reads the code that is present in it and through a process (not explained as not required here) we get Protein that is made up of Amino-Acids and this process is called Translation. These proteins can be made into Enzymes, Proteins have different structures and can be made into all sorts of things and codes for all of these proteins are included in DNA and this gives an overview of Molecular Biology
The outer layer of the cell consists of the Lipid Bilayer and the outside layer of the nucleus is a double layer of the Lipid Bilayer. This Lipid Bilayer consists of a hydrophilic layer at the bottom and top and the middle gap would be lipophylic. It has also got a Receptor called ACE2 Receptor
Now for this scenario lets bring in the coronaVirus, An interesting fact is that the outer layer of the virus is also made up Lipid Bilayer exactly the same as a normal cell, This Lipid Bilayer consists of proteins and the most important of those proteins is the S-Protein, There are other proteins as well like M and E protein which have their own functionality like binding the cell together and is of less concern for us, The inside of the cell consists of a very long RNA coiled as shown in the figure which is made up of N Protein, which means CoronaVirus is an RNA virus
Now let’s come to the interaction of the virus with the human cell, The ACE2 receptor that is found on the outer layer of the cell binds perfectly with S-Protein when it comes in contact and the resulting looks something as shown in the below image
Now we can see that all the Viral content that was present in the Virus cell comes in contact with the cytoplasm of the Human cell, Now since the viral RNA is in the cytoplasm of the cell lets Redraw to see how it looks, To our surprise, it is exactly like the human RNA with 5’(five prime) in the beginning and 3’(three prime) at the end respectively. Also, note that the outer layer of the human cell is infused with the outer layer of the virus-cell to act as one continuous outer layer, Now the S protein becomes a part of this outer layer and this is a mark for the immune system that a foreign body is present in the cell (in this case S Protein) and needs to be destroyed
In the same time, Unknowingly (unable to distinguish between RNA of human cell and Virus cell) the Ribosome march onto the virus RNA, read it’s genetic code as it moves from 5’(five prime) end to the 3’(three prime) end (ribosome traveling from 5′ to 3′ is called +ve RNA ) and makes a protein called RDRP ( RNA-Dependent RNA Polymerase) This protein is called so as it does not have any DNA code that was transcribed to RNA, instead solely dependent or made up of RNA itself.
Now the protein RDRP formed takes the +ve RNA and starts traveling from 3′ to 5′ making a new contradictory RNA called -ve RNA and the process continues making +ve strand and -ve strand RNA rapidly, but sometimes the RDRP protein may not be able to cover the full length from 5′ to 3′ or vice versa and thus we get a shorter copy of RNA called SGRNA (Sub Genomic RNA) and RDRP will make copies of both +ve SGRNA as well as -ve SGRNA
Now the Ribosomes can read all the newly created RNA by RDRP and Ribosomes produce RDRP protein again for all the full RNA and even more interestingly it creates the sub proteins E and M from SGRNA which is Vital for the Virus, and now your cell system is Hijacked by the virus in a clever way and your own Ribsome is contributing for the formation of new virus cells unknowingly for its own destruction and this process continues, the completed virus with the help of ribosomes moves out of the cell ( the reverse process of how it entered in ) to effect new cells and millions and millions of New Virus are formed!
The ACE2 receptor that we told earlier is present on the lower portion of your respiratory tract and with all the foreign bodies present, the immune system starts attacking these Hijavked cells to destroy it which causes swelling in this portion, results in leaking of fluids and cause Pneumonia
Now u can go ahead and read medical journals, understand all the vaccine research and medication that is being prepared and news that u see on any of your media with a new perspective
So how can we stop this? keep thinking we will be back with a new article, share this knowledge with your loved ones and keep supporting!
Thanks to Medcram for helping with this topic!