- SARS-CoV-2 can mimic the proteins of a human cell to evade detection by the immune system.
- Once inside the cell, it can replicate itself and infect the rest of the host.
- Researchers have managed to capture the proteins' structure, which may help to develop a remedy.
New research published in Nature Communications has found out just how sneaky the virus really is.
How an RNA virus works
First, it's important to understand that the coronavirus is an RNA virus, which means it needs to inject a cell with its RNA in order to replicate itself. DNA viruses already have the coding to replicate themselves, like in the case of herpes.
Beyond binding itself to ACE2 receptors – a popular method for infection – the coronavirus is also able to mimic certain single-stranded RNA molecules related to a cell's genes, making it easier to enter without triggering the body's protective mechanisms.
Understanding how the virus does this on a molecular level is vital for creating effective treatments and vaccines against Covid-19 by targeting its weaknesses.
Makeup of the coronavirus
The SARS-CoV-2 strain has a 5' cap structure at the beginning of its genome and ends in a 3' poly tail at the end of its genome. This acts as a messenger RNA (mRNA) that's in charge of translating its genetic sequence into specific proteins.
In this case, those proteins end up mimicking human mRNA through methylation of the first nucleotide of the viral strain, passing into the cell unobstructed without triggering the immune system's alarm bells. Once the virus is in the cell, it can replicate itself and spread to the rest of the body.
The researchers managed to create a 3D structure of a certain protein – nsp16/nsp10 heterodimer – responsible for this methylation process by using X-ray crystallography. This technique can read the atomic and molecular structure of proteins and biological macromolecules.
The researchers also found a binding site unique to the virus that helps it bind to cells in the human body that could specifically be targeted by antiviral compounds.
Being able to visualise these proteins and how the mRNA cap is methylated means scientists could develop effective antiviral drugs to prevent this from happening and make the coronavirus more visible to the immune system.
It could also help contribute to fighting other types of coronaviruses besides Covid-19.
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