The coronavirus that the World Health Organization calls the number one enemy in the world is not the same virus that appeared in Wuhan in the last days of 2019.
Sars-Cov-2, as the official name of the virus is, has mutated. While scientists around the world are recording thousands of mutations or changes in the genetic code of the virus, so far only one has been singled out that is likely to change behavior, reports the BBC.
Questions are being asked as to whether the virus is therefore more contagious or deadly in humans and whether it could pose a threat to the success of a future vaccine that has not yet been created.
The coronavirus actually changes quite slowly when compared to a viral infection such as the flu. With a relatively low level of innate immunity in the population, no vaccines and few effective treatments, the coronavirus is not under pressure to adapt. So far, it is well maintained as it is.
The only significant mutation, called D614G and located inside the protein that creates the top of the virus and uses it to break into our cells, appeared sometime after the outbreak of the epidemic in Wuhan, most likely in Italy. As many as 97% of samples are now recorded worldwide.
It is unknown at this time whether this dominance of the mutation is sufficient to give the virus any advantage or whether it is actually a coincidence.
Viruses are constantly mutating
“Viruses don’t have a grand plan. They are constantly mutating and while some changes will help the virus to reproduce, some can prevent it. Others are simply neutral. They are a side effect of virus reproduction, ”said Dr. Lucy van Dorp of UCL London.
“They stop the virus so they don’t change its behavior”, she explained. The mutation that appeared became widespread because it occurred at an early stage of the spread of the virus, and this phenomenon is known as the founder effect.
Dr. Lucy van Dorp and her team believe this is a very likely explanation for why the mutation is so prevalent, but at the same time it is controversial.
An increasing number of virologists, most likely most of them, believe, as explained by Dr. Thushan de Silva of the University of Sheffield, that we have enough data to say that this version of the virus has a selective advantage, evolutionary, over the earlier version.
“While there is not yet enough evidence to say that it is more easily transmitted in humans, it is certain that the mutation is not neutral,” argues Dr. de Silva.
Research conducted in the laboratory has shown that the mutated virus enters human cells more easily than the original version, say Professors Hyeryun Choe and Michael Farzan of Scripps University in Florida.
“Changes in the proteins used by the virus to better adhere to human cells appear to allow it to function more effectively,” they argue, but draw a line here.
Professor Farzan argues that the proteins of these viruses are different in a way that suggests they are better transmitted, but this cannot be proven.
The mutated virus has a higher transmission power than the original version
Dr. Neville Sanjana of the Genome Technology Center at New York University who works on Crispr gene modification technology has gone a step further. His team reworked the virus by making changes at the protein tip, and then confronted it with the Sars-Cov-2 virus from its original focus in Wuhan in human tissue cells.
He believes the result showed that the mutated virus has a higher transmission power than the original version, at least under laboratory conditions. There is indirect evidence that the mutation makes the coronavirus more transmissible in humans.
Two studies suggest that patients with a mutated version of the coronavirus have higher amounts of the virus in swab samples.This could lead to the conclusion that they are more contagious to others. However, there was no evidence that these people had more severe symptoms or that they stayed in the hospital longer.
So, the fact that the virus has become more transmissible does not mean that it has become more deadly. When it comes to coronavirus transmission, viral load is only an indicator of how much the virus is spreading within a single person. It does not necessarily show how good he is at infecting others.
The gold standard of research, controlled testing, has not yet been conducted. This could, for example, involve infecting animals with one version or another to see which spreads better among the population.
One of the research leaders, prof. Bette Korber from the Los Alamos National Laboratory claims that there is no consensus, but the idea that the mutation has increased the viral load of patients “becomes less controversial the more data is collected.”
When we look at the population as a whole, it is difficult to assess and say that the virus has become less contagious. Its course has been drastically altered by interventions such as “lockdown”. Professor Korber says the fact that the mutation is now dominant everywhere, including China, suggests it is spreading better among humans than the original version of the virus.
Whenever there are two variants in circulation, a new one will prevail.The D614G variant is so dominant that it is now a pandemic. This has been the case for some time, perhaps even since the start of the pandemic in the UK or even in the US East Coast area.
And while there is increasing evidence that this mutation is not neutral, it does not necessarily change the way the virus should be thought about and spreading. Also, it should be emphasized that this study should not have an impact on vaccine development and its efficacy. There is some evidence that the new mutation is also sensitive to antibodies that can protect us from re-infection.