They said viruses need their RNA to remain stable so that they can resist efforts from the host’s immune system to degrade their genetic material.
In the study, published in the journal Biochemical and Biophysical Research Communications, researchers used a new tool to determine what chemical sequences stored in the genetic material of the viruses, their RNA, are more stable.
The scientists used a new technique called Fate-seq, which can determine the fate of a genetic sequence — whether it will persist or degrade based on its stability.
As part of the technique, the researchers cut the viral genome into short fragments.
They explained that by doing this even extremely dangerous pathogens become harmless.
The scientists then synthesised the RNAs from the fragments of virus genomes, and examined their fate.
This process included checking the genetic material for stability, by using next-generation sequencing, which allows researchers to quickly and simultaneously identify the exact sequence of individual strands of RNA.
Overall, they assessed 11,848 RNA sequences from 26 virus genomes, including that of SARS-CoV, the virus that caused the SARS pandemic which killed 774 people in the first half of 2003.
The researchers found a total of 625 stable RNA fragments of which 21 were from SARS-CoV.
Two of the stable fragments from the SARS-CoV are very common in other similar coronaviruses like SARS-CoV-2 — the virus behind COVID-19 — the scientists said.
Comparing these 21 fragments to the full genetic sequence data available for the other types of coronaviruses, they showed that two of them are likely form stem-and-loop structures.
The researchers explained that the stem-and-loops are short pieces of RNA which, instead of remaining a straight line, fold forward and bind onto themselves, forming a hairpin shape.
One of the stable fragments, they said, only forms a stem-and-loop in the COVID-19 virus, not the SARS virus due to the few small but important differences in the viruses’ RNA codes.
“The stem-and-loop structure of this SARS-CoV-2 genetic fragment is very stable in computer models and we propose that this structure might enhance survival of the virus,” Akimitsu said.
The scientists said these folding RNA sequences, which could affect the stability of the virus, may offer possible targets for the treatment of viral infectious diseases like COVID-19.