Context

Researchers in the United States have unveiled the structure of the “spike protein” of 2019-nCoV, the virus behind the current coronavirus disease outbreak.

About:

• Coronaviruses are a family of viruses that cause illnesses ranging from the common cold to more severe diseases such as severe acute respiratory syndrome (SARS) and the Middle East respiratory syndrome (MERS).
• The World Health Organization (WHO) has declared the virus a global health emergency. Also, the WHO announcedan official name for the disease- coronavirus disease 2019, abbreviated as COVID-19.
  • In COVID-19, ‘CO’ stands for ‘corona,’ ‘VI’ for ‘virus,’ and ‘D’ for the disease. Formerly, this disease was referred to as “2019 novel coronavirus” or “2019-nCoV.”

What is a spike protein? 

• A viral spike protein is like a key that “unlocks the door” to gain access to the cells of a specific host — humans, in this case.
• The researchers defined the structure of 2019-nCoV’s spike protein using a technique called cryogenic electron microscopy, or “Cryo-EM”.
• This involves cooling the protein to below -150 degree Celsius so that it crystallises and then its structure can be determined with near-atomic resolution.

Another discovery:

• They also identified the “keyhole”, the host cell receptor: it is a human protein called angiotensin-converting enzyme 2 (ACE2).
• This is the same human receptor protein targeted by the earlier SARS coronavirus.
• But, disturbingly, the researchers found that 2019-nCoV binds to ACE2 with much higher affinity (10-20 times higher!) than SARS.

So what about a vaccine? 

• Both viruses attack the same protein on human cells, and the already available antibodies against SARS-CoV would work against 2019-nCoV.
• This means a stronger solution to this problem is still far away.
• Globally, the competition is heating up to hunt for the best anti-2019-nCoV vaccine.
• The earliest clinical trials to test a suitable vaccine will not be available until several months or even a year after a candidate vaccine is identified, and the global coronavirus outbreak may well be controlled by then.

Significance of the discovery:

• Knowing the structure of the virus’s spike protein gives us crucial information about exactly how the virus infects host cells.
• The discovery of the 2019-nCoV spike proteinstructure, therefore, represents both good news and bad.
  • The good news is now we know what it looks like, it will be easier to find the most suitable weapon against the virus.
  • The bad news is the enemy is much stronger than we thought, and our current ammunition depot doesn't have anything efficient against it.