It is possible that a mutation in the Delta variant has flown under radar, which could explain why it is twice as infectious than previous strains.
Scientists who are currently tracking the Covid mutation have focused their attention on changes in the virus’ spike protein. This is what it uses to infect cells.
These alterations were believed to have made it easier for Delta virus to spread between people, and for their immune systems to recognize and defend against it.
Researchers believe that an inconspicuous mutation in the virus’ structure could have played a significant role in the strain’s rise in popularity.
Their study found R203M — which is unique to Delta — allows the virus to inject up to 10 times more of its genetic code into host cells than older versions of the virus.
Covid is a virus that causes healthy cells to release more viruses, which in turn infects more cells and allows them to multiply.
MailOnline has been told by experts that Delta may be responsible for people infected by the virus having a much higher viral burden than those infected with earlier versions.
Scientists studying the Covid mutation have focused their attention until now on changes in the virus’ spike proteins, which it uses for infection. Researchers now believe that a subtle mutation in the virus’ N protein could have played a crucial role in the strain’s rise to world dominance.
In the latest study, researchers at the University of California tweaked a fake version of the original Covid virus to include the R203M mutation.
The researchers then compared the modified strain to the original virus by observing how it interacted in a lab with lung cells.
The team — led by Nobel Prize winner Professor Jennifer Doudna — were ‘surprised’ to find the R203M deposited 10 times more mRNA than the older virus.
They then created a coronavirus that included R203M to strengthen their findings. This made it 51x more infectious than the original virus.
Professor Lawrence Young, who was not part of the study, stated that it confirmed a growing suspicion about Delta’s virulence beyond spike mutations.
MailOnline was informed by a Warwick University virusologist that spike protein modifications help unlock cells, while R203M ‘enhances their fusion process’.
R203M modifies Covid’s Nucleocapsid, (N), which is a protein layer that surrounds the virus’ genetic information or genome. It is hidden away within the virus.
The N protein plays a key role in stabilizing and releasing the virus’ genetic material once it enters the body.
MailOnline was informed by Professor Lawrence that the process was “a bit like wrapping up sweets”.
“I would describe the Delta N protein’s effect as enhancing the process through which the virus genome is packaged into virus particle.
“It increases the efficiency of virus reproduction – this results is more virus being produced and transmitted.
It is distinct from the spike protein, which protrudes above the surface and binds with cells.
Dr Simon Clarke, a microbiologist at Reading University who was not involved in the research, described the finding as ‘really interesting’.
“When the virus infects a cell, it must get all its genetic material into that cell. Even 99 per cent is not enough.
It’s like having the blueprints for a car, but not the key components that will make it run.
This seems to make the process more efficient and faster in Delta with ‘R203M.
Dr Clarke said that while R203M was ‘definitely important’, mutations on the spike protein were still playing a key role in Delta’s increased infectivity.
He claimed that this was due to the fact that vaccines which target the spike protein were being less effective against the variant.
“I don’t understand how that could be possible.” [R203M] could account for less sensitivity of vaccines, so it tells us we need to be looking at other things as well as the spike protein.’
The study, published in the journal Science, also looked at other variants which have changes on their N proteins and found they too were also better at infecting cells.
The Alpha, or Kent variant, deposited seven-and-a-half times more genetic code than the original virus while for Gamma, formally the Brazilian variant, it was 4.2 times.
Professor Lawrence urged vaccine manufacturers to consider these findings when they develop the next generation Covid jabs.
He said: ‘It stresses the need to consider the use of second generation vaccines that contain the N protein along with the spike and perhaps other virus proteins.’
‘It has always been clear that other changes in virus variants would contribute to increased ‘virus fitness’.
“But these have been overlooked due to the over-focus on spike as the current major vaccine target.
Dr Clarke stated that it was also possible that an antiviral drug could be developed to target the mutation.