Biologists led by Yale University professor Joan Steitz discovered that the genome of the new type of coronavirus contains instructions for the production of short RNA molecules that suppress the work of innate immunity genes.
Human and other animal cells can produce short strands of RNA that detect the presence and control the activity of certain genes.
The authors of the new work found that COVID-19 acts in a similar way in order to hide its presence inside cells and suppress the work of their innate immunity in the first phases of infection.
In order to understand how the virus works, the authors observed how short RNA molecules that the body produces interact with the viral genome in infected cells. The researchers monitored changes in the activity of proteins responsible for the preparation and transport of microRNAs, as well as shifts in the activity of various human and viral genes.
As a result, it turned out that the penetration of coronavirus into human cells has almost no effect on what types of microRNA they produce. At the same time, scientists discovered that the viral gene ORF-7a contains instructions for assembling a short RNA molecule, dubbed vmiR-5p.
Surprisingly, infected cells produce short viral RNA molecules similar to their human counterparts. One of these molecules, vmiR-5p, inhibits the BATF2 gene, which plays a key role in the production of antiviral interferon proteins.
This means that viral RNA suppressed the production of a gene associated with neutralizing viral infections.