Prelims cum Mains Science & Tech

Why do some Covid-19 patients lose their sense of smell?

 #Covid-19 |  

Context of the topic:

      • World Health Organization has recently added anosmia (loss of smell) into the list of possible symptoms of the coronavirus infection.
      • Also, a new study in mice, recently published in ACS Chemical Neuroscience, has sought to explore why this symptom appears in some Covid-19 patients.


Theme of the topic: Reason of Loss of smell in some Covid-19 patients.


How does a study on mice applicable to humans?

      • It is known that the entry proteins have similar expression patterns among mammalian species which means that the mouse is a suitable model for the human condition.


How the virus works:

      • SARS-CoV-2 hijacks two proteins to invade human cells:
        • ACE2 (the cell surface receptor): It provides the entry point for the virus
        • TMPRSS2 (the protease): The virus uses this protein to replicate its genetic material.


Summary of the Study:

      • The two proteins mentioned above required for SARS-CoV-2 entry and replication are produced by cells of the nasal cavity that contribute to odor detection.
      • Scientists earlier weren’t sure which cells in the epithelium express the proteins and could potentially be infected by the virus.
      • Olfactory epithelium is the tissue lining the nasal cavity, that is involved in smell.
      • The sustentacular cells function as metabolic and physical support for the olfactory epithelium. These sustentacular cells of the nose help transfer odors from the air to neurons.
      • Now, researchers found that ACE2 and TMPRSS2 are expressed in sustentacular cells of the olfactory epithelium. In contrast, limited to no expression was found in most olfactory receptor neurons.
      • Finding: The scientists are now claiming that it is the sustentacular cells in the epithelium in the nasal cavity that are involved in SARS-CoV-2 virus entry and impairment of the sense of smell in COVID-19 patients.


Way ahead:

      • The future studies should examine whether sustentacular cells can pass the virus to neurons, which could provide SARS-CoV-2 a route to infect the brain.


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Wish you a very Good luck 🤞



     PT 2021 | SSARP Education Pvt Ltd. | All rights are reserved |

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