Why in news?
Scientists reported that they have identified two specific types of cells in the nose as the likely initial infection points for SARS-CoV2, the novel coronavirus that causes COVID-19.
How does it work?
- The entry of the virus takes place by means of a “lock and key” effect. Like all 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, which 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, which allow the virus to reproduce and transmit itself inside the cell.
Understanding the study’s findings
- The new study has identified the specific cells where the mechanism of entry most likely comes into play when the virus begins it attack – these are the goblet and ciliated cells in the nose.
- The two entry proteins were also found in cells in the cornea of the eye and in the lining of the intestine.
- The researchers said this suggests another possible route of infection via the eye and tear ducts, and possible oral-faecal transmission.
- The two cell types in the nose, where the proteins were expressed at the highest levels, are located at a place that is highly accessible for the virus.
- The virus is thought to be spread through respiratory droplets produced when an infected person coughs or sneezes.
- Goblet cells are mucus-producing cells on the surface of organs, and are found along the respiratory tract, along the intestinal tract, in the upper eyelid etc.
- Ciliated cells are hair-like cells, again occurring on the surface of various organs, and help sweep mucus, dust etc to the throat, where it can be swallowed.
How does the knowledge help?
This information can be used to better understand how coronavirus spreads. Knowing which exact cell types are important for virus transmission also provides a basis for developing potential treatments to reduce the spread of the virus.