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