Coronaviruses including SARS-CoV-2, which causes Covid-19, get their name from the “corona” or crown shape created by the protein “spikes” on their surface. These spike proteins bind with human proteins to initiate the process of infection. These spikes have been extensively studied during the pandemic. Now, scientists have made detailed images of those spikes in their natural state — while they are still attached to the virus, and without using chemical fixatives that might distort their shape.
Their method, which combines cryogenic electron microscopy (cryo-EM) and computation, is described in a study in the Quarterly Reviews of Biophysics Discovery. The researchers said the method should produce quicker and more realistic snapshots of the infection apparatus in various strains of coronavirus — a critical step in designing therapeutic drugs and vaccines.
“The advantage of doing it this way is that when you purify a spike protein and study it in isolation, you lose important biological context: How does it look in an intact virus particle? It could possibly have a different structure there,” senior author Wah Chiu, a professor at the US Department of Energy’s SLAC National Accelerator Laboratory and Stanford University, said in a statement from SLAC.
The research team looked at a much milder coronavirus strain called NL63, which causes common cold symptoms and is responsible for about 10% of human respiratory disease each year. It’s thought to attach to the same receptors on the surfaces of human cells as SARS-CoV-2 does.
The team also identified places where sugar molecules attach to the spike protein, a process that plays an important role in the virus’s life cycle and in its ability to evade the immune system.
Source: SLAC National Accelerator Laboratory, Stanford
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