Understanding the corona virus

The corona virus commonly known as COVID 19 over the past year has caused the world to come to a complete standstill as it continues to wreak havoc and has led to a numerous amount of deaths. The best thing we can do is stay inside, wear masks and implement several precautions : washing hands daily, use of sanitizers as well as immense cleaning of everything that comes in contact with us. In order for scientists to have had developed vaccines , they needed to understand how the virus worked and why it was so deadly. Was the virus airborne? How did it affect our respiratory system? What made it different from its precedents? How fast was its mutation rate? These were all questions that had to be heavily explored before the vaccine. As of 2021, there are vaccine drives after effective trials being conducted. Is there the pandemic that put our world on pause finally coming to an end?

Molecular Biology Of The Coronavirus

Proteins are vital for the working of any living organism. They are needed for growth, tissue repair, formation of pigments, antibodies, enzymes as well as hormones. They also are needed for the coordination and communication within our systems and organs, specifically the mRNA(messenger RNA) which is genetic material that contains specific instructions for certain functions in our body. While a human cell deploys and uses at least 20,000 proteins, a virus deploys less than 33, this is however enough. No antibiotic can act upon a virus as :

(1) it does not have a cell wall and

(2) a virus cannot grow, reproduce or move outside a living cell.

Only when it hijacks a living cell's control system(host cell) it starts to make miniature copies of itself; slowly invading and destroying the organism. The protein spikes on the virus bind to a protein on the human cell known as ACE2. Usually ACE2 helps to control the blood pressure, yet when it binds with the virus it causes the membrane to fuse and allows the virus' RNA to enter the cell. Once inside, the virus then takes over the host cells protein making center and causes it to translate RNA and make new copies of the virus. The RNA of the virus also codes for certain proteins that continue to stay inside the host cell these are of three types :

(1) prevents body from sending out signals to the immune system

(2) helps to send out more virions

(3) makes the virion more resistant to the immune system.

Structure of the virus

This virus is about 80 to 120 nanometers centimeters thick. It consists of a protein envelope around RNA along with protein protrusions outside the sphere. Inside the genome RNA also contains the nucleocapsid protein. The membrane of the virus consists of three main proteins (1) Spike : this is a glycoprotein forming peplomers on the surface, helps it to attach to specific cellular receptors (2) M protein : contains an ectodomain(helps initiate contact with surface and outside of cell) and cytoplasmic tail(helps in virus budding and assembly).

Deadly features

● This is one of the few viruses with RNA that have a proofreading mechanism which prevents the collections of mutations that can weaken the virus, this is why it is immune to drugs like ribavirin which otherwise stimulate mutilations which harm the virus.

● They have the ability to frequently recombine with other close coronavirus relatives.

● On the surface of the virus, there are spike proteins which are extremely effective in binding to the ACE2 receptors in human cells.

● The enzyme Furin on the surface of the host cell causes the breakdown of the spike protein(using it's cleavage site) releasing fusion peptides which further help the fusion of host cell membrane and virus membrane, causing virus RNA to enter cell and replicate.

● The RNA is then translated into proteins which help in producing more virus copies which can then leave the cell onto another cell.

● This coronavirus is more dangerous then its previous relatives as it causes harm to both the lining of the respiratory tract as well as the lungs.

Drugs that look promising and how they work

● Remdesiver : this is a prodrug which is usually inactive at time of injection. Once inside the host cell it metabolizes to the form remdesiver triphosphate. This is similar to the nucleotide adenosine triphosphate which forms when RNA replicates its genome. Thus, while producing copies the RNA mistakes the remdesiver triphosphate as the adenosine triphosphate an incorporates it in. The RNA replication process thus slows down.

● Dexamethasone : It is a glucocorticoid drug which has anti inflammatory properties and is needed to prevent an unrestrained immune response. In terminally ill COVID-19 patients, the immune system reacts by producing cytokines this however when increases can affect normal cells too. If these affected cells are in the respiratory tract and lungs it can cause acute respiratory distress. Almost all cells have receptors for dexamethasone when it binds with these receptors it produces phospholipase A2 which is an enzyme blocking production of inflammatory mediators. This is a drug which contracts the heightened response by our immunity system. Yet it is a immunosuppressive thus must be taken in controlled amounts as it can make the sick patient worse.

- Written By: Khwaish Sethiya