Context: Scientists have identified two specific types of cells in the nose as the likely initial infection points for SARS-CoV2 which is the novel coronavirus that causes COVID-19. 


  • Previous studies have shown what happens at the cellular level. 
  • The entry of the virus takes place by means of a “lock and key” effect. 
    • Like other coronaviruses, SARS-CoV2 consists of a fatty envelope with a “spike protein” on the surface. 
    • The spike acts as the “key” to “unlock” a protein on the human cell, called ACE2, that acts as the receptor for the virus. 
    • Once inside the cell, the virus uses a second protein, called TMPRSS2, to complete its entry. 
    • TMPRSS2 has protein-splitting abilities that allows the virus to reproduce and transmit itself inside the cell.

Findings of News Study:

  • The new study have reported that they have identified the specific cells where the mechanism of entry most likely comes into play when the virus begins its attack. 
  • These are the goblet and ciliated cells in the nose.
    • Goblet cells
      • They are mucus-producing cells on the surface of organs
      • They are found along the respiratory tract, along the intestinal tract, in the upper eyelid etc. 
    • Ciliated cells -
      • They are hair-like cells, again occurring on the surface of various organs.
      • They help sweep mucus, dust etc to the throat, where it can be swallowed.
  • For the research, they turned to the Human Cell Atlas, an international consortium that aims to create comprehensive reference maps of all human cells.

Source: Journal Nature Medicine

  • Although Goblet and Ciliated cells are found in the cornea of the eye and lining of intestine but most likely they are attacked by Covid 19 virus on the nose where their relative abundance is high.
    • Also the two proteins which act in a lock and key relationship are available in great quantity on the nose.

Relevance of New Findings:

  • This is the first time that these two cell types have been pinpointed as the likely points of initial entry. 
  • The researchers believe their identification could help explain the high transmission rate of COVID-19. 
  • This information can be used to better understand how coronavirus spreads.
  • This also provides a basis for developing potential treatments to reduce the spread of the virus.

Human Cell Atlas:

  • It is an international consortium that aims to create comprehensive reference maps of all human cells.
  • In London on 13 and 14 October, 2016, a collaborative community of world-leading scientists met and discussed how to build a Human Cell Atlas—a collection of maps that will describe and define the cellular basis of health and disease.
  • It will be basis for both - 
    • understanding human health and 
    • diagnosing, monitoring, and treating disease.

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