COVID-19: BRAIN DAMAGE MAHCANISM UNCOVERED कोविड-19: मस्तिष्क क्षति तंत्र का पर्दाफाश…

COVID-19: BRAIN DAMAGE MAHCANISM UNCOVERED कोविड-19: मस्तिष्क क्षति तंत्र का पर्दाफाश…

• While COVID­19 continues
  to be active in several western countries, its severity
  has diminished. 

• A vexing
  issue however is Long COVID, a set of long ­term
  health problems that linger
  for several months following recovery from the infection. 

• A recent Harvard study
  comparing infected and
  non­infected individuals,
  reported a 10% risk of getting Long COVID-19. 

• A prominent Long COVID-19 symptom is brain fog,
  which involves difficulty
  focusing, memory impairment and challenges in decision­ making.  

• Shrinking parts
  A recent study from Stony
  Brook University in the
  U.S., utilising cognitive assessment tests, identified a
  significant intellectual decline following COVID-19. 

• This
  was particularly pronounced among those
  with Long COVID. The exact mechanism remains
  unclear, but U.K. Biobank
  MRI studies had demonstrated shrinking of parts
  of the brain following
  COVID-­19.

•  In this context, researchers from the University of Queensland and
  Macquarie University of
  Australia, in collaboration
  with the University of Helsinki recently made some
  startling discoveries. The
  results were published in
  the journal  Science
  Advances.
  Using specialised laboratory cells that mimic the
  human brain they found
  that infection by the SARSCoV­2 virus resulted in individual brain cells fusing
  together as one.
•  
• This could
  happen between two neurons, two glial cells or between a neuron and a glial
  cell. It could also involve
  more than two cells. 

• Process of fusion
  By measuring the inflow of
  calcium ions into the cell,
  they further demonstrated
  that the process of fusion
  also affected their function.

• Instead of firing individually, the fused neurons
  fired all at once. This could
  disrupt communication
  between nerve cells. 

• Interestingly, the cells did not
  die. 
  In effect, they discovered a new disease state
  of the brain in COVID-­19,
  where the cells are structurally and functionally altered, yet remain alive.

• This is distinct from the
  previously known outcomes of viral infection of
  the brain, which are cell
  death and inflammation.

• Apart from SARS­CoV­2,
  which is known to enter
  the brain by disrupting the
  blood ­brain barrier, viruses such as rabies, HIV and
  Nipah are also capable of
  infecting the brain. 
  The scientists then went
  on to study the mechanism
  of cell fusion. When the virus infects a cell, it causes
  fusion proteins to be expressed on the surface of
  cells. 

• These proteins latch
  on to a neighbouring cell,
  eventually the two cells becoming one.
  Fusion of brain cells not
  only alters the structure of
  the complex, but also
  makes the cells dysfunctional. 

• This process is
  called syncytium formation, wherein the components of one cell freely flow
  into others.
•   
• Viruses use this as a
  clever method for cell­ to cell spread, while staying
  out of reach of antibodies
  that lurk outside the cells.
  COVID-­19 is known to induce the same effect in
  lung cells.
•  
• The SARS­CoV­2 virus
  uses its spike protein for
  cell fusion. However, the
  spike protein used in the
  vaccine, being an altered
  version of the original, is
  not fusogenic. 

• Therefore,
  there is no concern of such
  a thing happening after
  vaccination. 
  The prognosis of Long
  COVID-19 is being studied. 

• While some individuals recover after several months,
  the outlook has been less
  optimistic for a substantial
  number of people. Being
  an all­new disease previously unknown to man,
  knowledge about COVID-­19
  will continue to evolve. 

COVID-19: BRAIN DAMAGE MAHCANISM UNCOVERED 

 

कोविड-19: मस्तिष्क क्षति तंत्र का पर्दाफाश