A BRIEF ON SARS COV-2

Post by: Shilpa Shantharam, Student

    Outbreak of COVID-19 pandemic which has led to the death of approximately 243k people worldwide is caused by a group of virus collectively named as CORONA. This group of virus acquires its name from a Latin term “corona” which translates to crown due to possession of proteinaceous crown like spikes on its outer surface. Although the initial symptoms caused by these virus appears to be similar to common cold, it is way more dangerous than it. What is corona? Why is human body vulnerable to its attack? How serious can it be? Let us try and find the solution for such queries

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 CORONAVIRUS

  There are more than hundred strains of viruses which come under this group, among them only

seven strains have been found to have effects on human body. In these seven varieties four strains leads to low risk pulmonary disease which doesn’t necessarily require medical attention, but the rest three namely SARS-COV (leading to Severe Acute Respiratory Syndrome), MERS- COV ( Middle East Respiratory Syndrome), SARS-COV 2 ( causes COVID-19) attacks lower respiratory organs. In the absence of proper medical attention, it may even lead to death. 

Microscopic image of SARS COV-2 , distinct proteinaceous
 spikes on its surface visible as greenish projection 

  
  SARS-COV 2 also known as NOVEL corona virus has led to 2019 outbreak in Wuhan, China then gradually spreading worldwide.
     The primary symptoms of this viral infection involves running nose, fever, cough, fatigue. Some people might even have symptoms like sore throat,nasal congestion, muscle ache and pain, diarrhoea, anosmia(insensible to odour), headache, etc. The infected person might not show the symptoms at the beginning as the incubation period is 2-14 days.

HOW DOES THE VIRUSE ATTACK HUMAN BODY?

     All the virus needs a respective host organism to replicate and survive. When the infected person sneezes, the scattered droplets of saliva comes in contact with a healthy individual in the vicinity and transmits the infection. Even coming in contact with the contaminated area ( area contaminated by sneeze or cough of an infected person) also leads to virus transmission. These transmitted virus directly enters nose or throat of the person. The inner linings of nose, lung and few other vital organs have cell surface receptors known as Angiotensin Converting Enzyme-2 (ACE-2), it’s main function is providing with vasodilation(widening of blood vessel) at necessary moments and hence helping in maintaining blood pressure. These receptors provide a perfect active site which is compatible to the protein spikes of virus and hence forming a pathway for the virus to enter the interior of the healthy cell. Once the virus enters the cell it starts to overpower the cell by reading it’s genomic content and rapidly replicating and making more copies of its own to infect the adjacent cells

(Virus entry into a healthy cell with the help of ACE2 receptors by key lock mechanism)

BODY DEFENCE TO TACKLE THE INTRUDER

    The defence system gets alarmed within some time of infection. The infected cell itself tries to notify the adjacent healthy cell by sending some chemical signals known as interferons. A set of chemicals are released known as cytokines and chemokines which initiates the mass dispatch of various defence cell to the infected area. These defence cells kills the unhealthy body cells. At this very moment the body tries to capture or expel these viruses. Runny nose or sneezing leads to expelling of the virus from the body and thick mucous cover in the inner linings of respiratory track to control the movement of the virus and provide them a physical barrier. All  these actions are summed up as symptoms of the infection. In case these symptoms are ignored or if the person was not immune enough to provide primary defence against the virus, the virus penetrates deep and enters lungs and alveoli and destruct the oxygen exchange system between  alveoli and the capillary and leads to pneumonia or Acute Respiratory Distress Syndrome.

(Cytokine inside the alveolar tissue leads to inflammation hence increasing the thickness of pathway for blood transfusion and hence decreasing the breathing capacity of the person)

    The furious action of immunopathogenesis itself acts as a harm to the body function, as numerous cell enters the alveoli at the same time increases the thickness between blood capillary and alveoli barrier hence decreasing the oxygen transfusion efficiency.

    Novel Corona is a highly communicable disease. We must be at our upmost hygiene to prevent its transmission. What are the different modes in which it transmits? Does housefly transmit the virus? Let us look at these in the next post

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REFERENCES:

https://www.who.int/health-topics/coronavirus

https://www.healthline.co

https://www.sciencemag.org

https://www.cdc.gov/coronavirus/types.html.