Repeated genetic mutation of COVID virus, a matter of concern?

All you need to know about the new Coronavirus strain. (photo:ianslife)
Representative image: IANS

Of late, the deadly SARS CoV-2 virus that causes the COVID-19 infection has been undergoing rapid genetic variations. The main reason for the rapid changes is because COVID-19 is an RNA virus. Unlike DNA viruses, the RNA variants have a higher chance of genes getting mutated repeatedly. However, SARS Cov-2 has comparatively lesser chances of genetic mutation among RNA viruses, mainly because they possess a proofreading mechanism that prevents further genetic changes after a certain degree. Therefore, many virologists believe that COVID virus is incapable of undergoing drastic genetic variations.

The COVID virus has continued to exist and circulate within the global population for quite some time, which is probably one reason why the virus keeps mutating. The mutating property, over a period of time, is likely to diminish the potency of the virus, and may ultimately reach a point when the pathogen ceases to exist, or at least continue to prevail in pockets of the global community in a much milder form just like that of a common cold infection. Hence, it is highly important to curtail the endemic nature of the virus and its future new variants through a potential proofreading strategy.

Studies show that the rapid pace of virus mutations across the world takes place at an approximate rate of one in every 10 days. However, the changes that are happening in some part of the virus genome may not always alter the trait of the virus as such, which is by and large capable of being highly contagious. Hence the mutations stand higher chances of weakening the natural power of the virus, rather than strengthening it. By and large, this means genetic mutations do help in curbing the super spreading behaviour of a virus like COVID-19. The phenomenon is called 'regression to mean' where genetic mutation happening in a virus with virulent behaviour will only help in suppressing the trait to a large extent.

The change in the behaviour of the virus is largely dependent on the alterations happening in external projections called spike proteins. We all know that the thick horny projections on the SARS Cov-2 virus enable it to enter the human body and merge with the receptors called ACE-2 in human cells. At this point, the outer covering of the virus ruptures so as to insert the genetic material in it into the cells. Hence the genetic alterations in the horny formations called spike proteins affect the general trait of the virus while acting on human cells. Though such changes mostly result in inhibiting the power of the virus, at times they do generate opposite effects. In such cases, the mutations in spike proteins can induce three kinds of characteristics to the virus.

High transmission is one such trait in which a few viruses acquire the power to attack human cells in a short span of time. In such a scenario a small amount of pathogens would be sufficient to disease a human body, particularly by gaining the ability to transmit the infection through aerosols.

Secondly, the virus can earn the quality of attacking people who have already gained immunity, especially on those who had earlier contracted the infection or received the COVID shot. The mutation can, therefore, help the pathogen to overpower the immunity of an individual.

Thirdly, the pandemic can get virulent in cases where more viruses enter the human body and multiply by themselves.

Moreover, there is also a potential risk of the virus achieving all the three characteristics simultaneously.

The World Health Organisation has termed the variants that enhance the viral property as 'Variant of Concern' or 'Variant of Interest'.

‘Variants of Concern’ are mutant viruses that have experimentally proved to boost the original trait of the virus. Meanwhile, ‘Variants of Interest’ are those viruses that do not directly exhibit their virulent behaviour or transmission power despite possessing mutating features to boost their features.

C.1.2., the South African variant discovered in 2021, is not typically a fresh virus, but draws lineage from the C.1. variant that was widely prevalent in the country during the first wave. Besides, another mutated variant of C.1 termed C.1.1 was earlier detected in the African nation of Mozambique. However, genomic surveillance shows it exhibited a minimum transmission rate, unlike the latest C.1.2. spike protein that has undergone a maximum number of genomic mutations. Of all the variants emerged so far, C.1.2. has clocked the most number of sequence changes.

Most of the genetic changes exhibited in the UK strain 'alpha’, the South African strain 'beta' and the Brazilian strain called 'gama' were displayed by the C.1.2 as well. Hence virologists pursue the latest genetic changes in the virus with added vigil.

The new variant has shown at least 14 mutations in the spike protein alone. The area in human cells where the ACE-2 receptors interact with the spike protein (receptor binding domain) has undergone three mutations alone. Shockingly, mutation has also crept into the furin cleavage site which allows the insertion of genetic material which is inside the virus into the human body. Hence modern science calls for extra alert against the new variant.

Almost all provinces in South Africa (six out of nine provinces so far) have reported the presence of this genetic variant, apart from many countries spread across Africa, Europe and Asia. Countries such as Mauritius, Zimbabwe, Botswana, China, New Zealand, Portugal, Switzerland and UK have recorded the sporadic presence of the C.1.2. variant.

Yet, the World Health Organisation has not categorised this variant either under the 'Variant of Concern' or 'Variant of Interest' categories, for that matter. Even then, there is a strong likelihood of including the variant under 'Variant of Interest' category.

Interestingly, the most commonly found variant in South Africa where the virus has hit hard is not C.1.2. but the delta variant. This explains that C.1.2. does not have a higher transmission power than the delta variant, say many experts. The latest observation is that the C.1.2. cannot be as contagious as the delta variant which has made its strong presence in India and Kerala.

To put things into perspective, Kerala has undertaken the complete genomic study of the COVID-19 virus and that of spike protein. Research activities in this direction are expected to help the state in immediately detecting the presence of the new variant if it shows up in Kerala at some point of time. Hence the situation calls for subjecting more samples for a detailed study.

The emergence of alpha, beta, gama, delta and even C.1.2 variants shows that regions with high incidence of infection stand higher chances of getting new variants. Therefore, it is more important to lay thrust on measures and a new protocol regime capable enough to stem the spread of the infection. COVID vaccines may not be effective in stopping the C.1.2. variant as they are against other genetic mutations. But they definitely can build a strong defence against symptoms and cheating deaths.

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