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STRUCTURE OF CORONA VIRUS AND IT'S MECHANISM OF ATTACK


 Structure and mechanism of attack of corona virus
Let’s talk about the structure of COVID-19 Virus SARS COV 2 and also the mechanism of its entry.
There are four families of corona Virus: -
1.       Alpha Corona virus
2.       Beta Corona Virus
3.       Gamma Corona Virus
4.       Delta corona Virus
Out of which Alpha and Beta corona virus has shown transmission in Human being till now.
Many outbreaks like the SARS (Severe Acute Respiratory Syndrome) outbreak in the 2002 and the MERS (Middle East Respiratory Syndrome) had been there in the past and both are related to the Beta Corona Virus family.
Now let’s talk about the COVID-19 Virus (SARS COV 2)

Structure of the COVID-19 virus
SARS COV 2 is a virus of the family of Beta Corona Virus. It has a lipid bilayer which has 5 main structural proteins on the outer membrane of it and many non-structural proteins which are essential. Following are the structural proteins: -
  • ·         Nucleocapsid protein
  • ·         Envelope Glycoprotein (E)
  • ·         Spike glycoprotein (S)
  • ·         Membrane Glycoprotein (M)
  •        Hemagglutinin esterase dimer




·        



As it is a member of corona virus family researchers sequenced the genome of the virus i.e. decoded the single stranded RNA into the form of nucleobases (Adenine, guanine, uracil, cytosine) and identified the region responsible for the protein synthesis. They found out the important sequences and named the regions as followed: -


It is sequenced and arranged in order from 5’ to 3’ of the RNA strand. The S part is responsible for the spike glycoprotein formation, similarly M for membrane glycoprotein and N for nucleocapsid protein.
To compare the similarity with the SARS COV AND MERS, the scientist also compared the all the three RNA sequences and spotted the changes that occurred in the RNA structure also concluded that SARS COV 2 have a more similarity to the 2002 SARS then the MERS.
The process of comparison is also called as multiple sequence alignment.
We can easily determine the changes that occurred in the in the genome sequence.

MECHANISM OF ATTACK OF COVID-19
Now let’s talk about the mechanism by which it hacks the host cell after entering into the body of the host.
It enters the body of the host through mucous membrane of the upper respiratory tract and eventually reaches to the lungs where Type 2 Pneumocytes are present which are the cell responsible for the production and secretion of surfactant. These cells have ACE 2 receptors. The spike protein gets activated by the TMPRSS 2 (trans-membrane serine protease enzyme) which results in the increased affinity of the spike glycoprotein to the ACE 2 receptors. So, the SARS COV 2 attaches to the ACE 2 receptor after which through the process of endocytosis the virus enters into the cell.

After the virus enters the lipid bilayer dissociates which resulting in the exposure of naked s-SRNA.
Now two things happen here: -
·     This RNA reaches to the ribosomes where it gets translated into polyproteins (large chains of proteins). These polyproteins are then broken down by the proteases in to several structural and non-structural proteins (i.e. Nucleocapsid protein, Envelope Glycoprotein etc.)
·       The RNA also replicates using the RNA dependent RNA polymerase enzyme.
Now what happens is that these RNA and protein formed goes to the endoplasmic reticulum and packs itself into a new viral entity. This is how the no. of virus increases into the cell. After this the virus exits the cell by exocytosis. And eventually the cell dies these viruses thus released goes and hack the new cells.

REFERENCES: -
  1.   http://www.ijp-online.com/article.asp?issn=0253- 7613;year=2020;volume=52;issue=1;spage=56;epage=65;aulast=Prajapat
  2.    https://www.ncbi.nlm.nih.gov/genbank/sars-cov-2-seqs/
  3.   https://en.wikipedia.org/wiki/Sequence_Read_Archive
  4.    https://www.nature.com/articles/nrmicro.2016.81
  5.    https://www.sciencedirect.com/science/article/pii/S2090123220300540

Compiled by: - CuriositySeeker
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