Corona Virus is mutating

With the dawn of the pandemic and the spread of the COVID – 19 virus throughout the world the possibility of this deadly virus to be changing as it is transferred from person to person became a question. Viruses have a high fondness to mutate themselves in order to evade the immune system. Compared to, other viruses SARS – CoV – 2 is changing much sluggishly. One very recurrently seen outstanding mutation is in the gene encoding the spike protein, which helps the virus particles to penetrate cells. At the 614^th amino acid position of the spike protein, the amino acid aspartate is regularly replaced with glycine because of a copying fault that altered a single nucleotide in the virus RNA. This is defined as the D614G mutation.  Mutations give rise to more transmissible forms of the virus.

Viruses that encode their genome in the RNA, such as SARS – CoV – 2, tend to mutate rapidly while they are being copied inside their hosts. This is because RNA copying enzymes are more predisposed to to errors owing to structural and molecular biological reasons.

Sequencing data proposes that the mutation rate of coronaviruses is much lesser than other RNA viruses, perhaps because of proof reading enzymes that corrects potentially lethal copying errors. A typical SARS – CoV – 2 virus accumulates only two single letter mutations per genome in a month. Even though a noteworthy amount of mutations can accumulate, most of them will have no importance for the virus’s ability to spread or cause disease, because they do not make any alterations in the shape of the protein. If any mutation has the ability to change the shape of the protein they are likely to harm the virus rather than to improve it.

Researchers suspect that any mutation if it helped the virus to spread faster, it would have occurred earlier when the viruses first moved into humans or developed the ability of competent human to human transmission.

More than half a year into the pandemic, it is still inexact whether the virus has is likely to evolve in to a worse direction or in to a more benign direction. Out of all the mutations, D614G is the most dominant strain so far irrespective of whether it is suggestively transmissible or not. The bigger question is why is the evolution so little and why mutations that affect the viral behavior are not developing? Scientists say that maybe it is due to the very little selection pressure acting on the virus as it spreads through a massive number of immunologically naïve people.

More than half a year into the pandemic, it is still inexact whether the virus has is likely to evolve in to a worse direction or in to a more benign direction. Out of all the mutations, D614G is the most dominant strain so far irrespective of whether it is suggestively transmissible or not. The bigger question is why is the evolution so little and why mutations that affect the viral behavior are not developing? Scientists say that maybe it is due to the very little selection pressure acting on the virus as it spreads through a massive number of immunologically naïve people.

There is an option, but by no means an inevitability, that the virus may attain mutations that can change its susceptibility to antibodies and immunity. But, grounded on the experiments done on other coronaviruses even if this situation was to occur, it would take years.

While a major part of the world is still susceptible to the virus it is questionable that immunity is presently a major factor in the virus evolution. But, as population wide immunity arises a stable sequence of immune evading mutations may aid the virus to establish itself. More harmful mutations could arise if antibody therapies against the virus are not used perceptively.

While adaptive variations might happen, at present there is a proposition based on scientific findings that the world is facing the same virus since the start of the pandemic.

Thankfully due to the very low rate of mutation in SARS – CoV – 2, it is expected that treatments will remain to be effective and with any luck the virus will not undergo any dramatic changes in the upcoming months. However, it is a community obligation to cooperatively work towards containing the virus and ending the pandemic, because longer the virus stays, the larger the chance of novel mutations to arise.

Author
S.M. Nirmali Samrakoon
Undergraduate-Immunology and Integrative Molecular Biology
Faculty of Science
University of Colombo

References

1. https://www.nature.com/articles/d41586-020-02544-6
2. https://www.sciencefocus.com/news/covid-19-is-the-virus-mutating/
3. https://www.sciencemag.org/news/2020/07/pandemic-virus-slowly-mutating-it-getting-more-dangerous
4. https://www.weforum.org/agenda/2020/09/coronavirus-covid-19-mutations-health-healthcare/