Spike proteins play an important role in how these viruses infect their hosts. Examples of coronaviruses include those that cause Severe Acute Respiratory Syndrome (SARS) and Middle East respiratory syndrome (MERS). Their spike proteins work a bit like shape-shifting lock picks. They can change shape to interact with a protein on the surface of human cells. Those spike proteins latch the virus onto a cell. This allows them to get entry into those cells.
On February 19, 2020, researchers described the 3-D structure of the spike protein on the novel coronavirus behind the 2020 global pandemic. This confirmed that the new virus’s spike protein also is a shape-shifter. What’s more, it clings to its target on human cells 10 to 20 times as tightly as the SARS spike protein does to the same target. Such a tight grip may help the COVID-19 virus spread more easily from person to person, researchers now say.
Like a key in a lock, these spike proteins fuse to receptors on the surface of cells, allowing the virus's genetic code to invade the host cell, take over its machinery and replicate.
—Bruce Lieberman
Their results, published in Science, confirm that the spike protein on the virus that causes COVID-19 is quite similar to that of its close relative, the SARS virus.
—Francis Collins
Using a powerful imaging technique , researchers from the National Institutes of Health, Weill Cornell Medical College and Yale University School of Medicine observed the motions of key proteins on the surface of HIV called spike proteins.
—Emily Mullin