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