Anything to worry about new mutations on SARS-CoV-2?

When the COVID-19 pandemic started, experts knew it was going to turn into a long distance race. From the first moment, the virus was treated with the experience acquired on other occasions and immediately the work on vaccines and drugs to stop it started. However, nature does not stop for nothing. Thus began an arms competition of the human being against the natural mutational capacity of SARS-CoV-2, adjusting to the hypothesis of the Red Queen to perfection. In a scenario free of defenses against the virus, this region would evolve to be more efficient by binding to its receptor on human cells, the ACE2 protein. In contrast, in a situation where the vaccine stopped the current spine variants, mutations in that region would be evolutionarily favored. Because they would be able to replicate in greater numbers regardless of their ability to join ACE2. This possibility is something the researchers work with. It has occurred in other viruses and it cannot be ruled out that SARS-CoV-2 will do so in the future.

From the beginning it was said that contagions had to be stopped for obvious reasons, such as preventing people from falling ill. But also to prevent the virus from reproducing and creating new variants that could eventually be less recognized by the vaccines in which they are working. SARS-CoV-2 is an RNA-type virus, which usually has a high mutation rate. Fortunately, the periodic sequencing of the coronavirus isolated in different parts of the world seems to indicate that in this case the variations are not appearing so quickly. Although more than 12,000 point mutations of a nitrogen base have been cataloged, none of them appear to imply a change in the lethality or infectivity of the virus. The ability to spread is another of the hot spots that are being studied on the virus genome. Although this can occur simply by random processes. As an example of this, the case of New Zealand shows that of the 217 entries of the virus, only 20% caused around 80% of the infections, although no genetic reason has been found in the virus for this and the hypothesis of it was simply by chance or the amount of viral load in each case.

As we knew the appearance of new strains was going to happen and it will not happen just once. The D614G variant of the spike protein (the one that binds to ACE2) was one of the first cases. Studies of this variant indicated that the amino acid change mutation did not alter the capabilities of the virus to infect, nor those of the potential vaccines that were being developed.

In early November a new SARS-CoV-2 strain with a mutation on the spike was detected in Norway. After several cases related to the mink fur industry, the transfer of the virus from human to mink and vice versa was confirmed. This outbreak, which is to be stopped with the sacrifice of 17 million minks, has been for many something precipitous. Mink outbreaks have emerged in five other countries apart from Norway. Contagion from humans appears to be common. In the farms these animals would have been infected by the workers. Later the virus would run between the mink populations multiplying and mutating. Finally, the lack of biosecurity measures when handling them would cause the same operators to be reinfected, but this time with other strains of the virus. At the moment the data to know if the strain (or strains) appeared in the Norwegian mink would be potentially more dangerous are being treated. However, it should be pointed out that the mere fact that the virus can find a natural reservoir outside humans from which to reinfect them would be a major problem when trying to eradicate the virus. As has happened with other viral diseases that have tried to be eradicated, the natural reservoir of the virus has to be treated to prevent new outbreaks from spreading to humans. In the case of SARS-CoV-2, we do not know exactly what this possible natural reservoir is. Even so, if the virus began to spread among different species, intervention and eradication would be much more complicated.

A picture of minks (left) and other from Siberia (right)

In Russia, in the frozen Siberia another new variant has been found. The competent authorities have sounded the alarm of a new strain that is mutating there, very possibly deriving from the genetic isolation that the virus has. According to experts from the country itself as well as from the US who have studied the effects of these mutations, the virus would be adapting to Siberian conditions and would not be more dangerous than other variants. Russia, the fifth most affected country by the pandemic worldwide, has a vaccine ready to be supplied. However, she had to quickly test this new mutation to see that the vaccine was still mimicking the virus enough that the immune system to which the vaccine was presented could also recognize the virus with the same antibodies. Fortunately, and according to the Vector Institute in charge of developing the vaccine, it seems that this mutation of the virus will not alter the efficacy of their vaccine.

Biblio:

Plante, J.A., Liu, Y., Liu, J. et al. Spike mutation D614G alters SARS-CoV-2 fitness. Nature (2020). https://doi.org/10.1038/s41586-020-2895-3

Kannan S, Shaik Syed Ali P, Sheeza A, Hemalatha K. COVID-19 (Novel Coronavirus 2019) - recent trends. Eur Rev Med Pharmacol Sci. 2020 Feb;24(4):2006-2011. doi: 10.26355/eurrev_202002_20378. PMID: 32141569.

Mousavizadeh L, Ghasemi S. Genotype and phenotype of COVID-19: Their roles in pathogenesis. J Microbiol Immunol Infect. 2020 Mar 31. doi: 10.1016/j.jmii.2020.03.022. Epub ahead of print. PMID: 32265180; PMCID: PMC7138183.

Yegor Aleyev. Mutating Coronavirus Discovered in Siberia. The Moscow Times. 17 Nov 2020

Daniel Boffey. Denmark tightens lockdown in north over mink Covid outbreak. The Guardian. 5 Nov 2020.

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