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The double mutant virus: What are the implications?

It’s been more than one year since the Covid-19 virus started wreaking havoc around the globe in the form of a pandemic. We saw the global economy crash, major airlines get grounded, many bankruptcies, and many jobs lost as a result of the debilitating effects of this virus. Currently, the virus has claimed almost 570 lives in Sri Lanka and 2.8 million deaths globally; the locally reported cases amount to more than 92,000 and globally, more than 128 million cases have been reported.

Within the span of one year, we have been on a rollercoaster ride with highs and lows; the deadly virus claiming lives and turning our lives upside down has definitely been the lowest point in recent history. With the emergence of the vaccines to combat Covid-19, we saw some light at the end of the tunnel, but we are at war with a deadly foe, an enemy that keeps evolving; when we cut off one head of the monster, it grows one more. We have seen the emergence of many new variants of the Covid-19 virus, some more dangerous than others. And now, the monster has grown two heads and become double-headed in what is being tagged as the “double mutant virus”.

Previously, we heard of a UK strain and a South African strain in the evolution of Covid-19, and there is a Brazilian strain also at the moment. Some of these variants have proved that certain vaccines are less effective against them.

Even at the earliest stages of detection in 2019, researchers believed that there was more than one strain of the virus. This theory about different strains of the new coronavirus originated from a study in China. The researchers were studying the structure of coronaviruses in animals and human beings, and it appeared that the samples from humans were not identical to each other.

And amidst all this chaos, we now hear of the new “double mutant virus”. The name itself strikes fear. Usually, when we hear the word mutant, we picture the mutants portrayed in popular movies and cartoons; we see them with special abilities and appearances as compared to the rest of the population. In a certain sense, that is the case with Covid-19 as well. All mutations in organisms are part and parcel of its evolutionary process that equips an organism for better survival. But in certain cases, some mutations prove to be deadly to the organism too.

It is the nature of viruses to evolve, and this is why it is so difficult to combat them, but some mutations prove to be more deadly than others. In order to understand the implications of these mutations, we need to understand why viruses evolve. This domain was discussed in earlier articles as well; however, it is important to revisit the facts.

 

Why do viruses evolve and what are the implications of viral evolution?

 

Similar to humans, plants, and all other living organisms, viruses are subject to the evolutionary process of “natural selection”; even though viruses on their own are not living organisms, as they require a living host to replicate in.

The host’s immune system employs various mechanisms to evade or fight the viruses, while the viruses evolve in ways to evade the immune system’s mechanisms in order to fulfil its objectives to replicate itself more and spread.

In the evolutionary process of viruses, the characteristics that increase its virulence tend to be carried forward and characteristics that tend to diminish its virulence are lost.

When humans develop immunity to a virus, they develop antibodies to that virus which usually attach to the outer surface of a virus and prevent it from entering the human cells. However, a virus which has mutated and has a slightly different structure to the pre-existing virus has an advantage in the fact that no antibodies have been developed to the particular structural anomaly that has been caused in the mutation. Many of the mutations in the viruses over time cause changes in the structure of the outer surface of the virus.

 

Viral mutation leading to new strains

 

Viruses have genetic material called RNA (ribonucleic acid), which is similar to DNA. When a virus infects a host cell, they attach to the cells and infiltrate them and make copies of their RNA in their efforts to replicate and spread.

When viruses replicate in a host, there are “copying errors” which cause mutations of the viruses in the structure of the virus, leading to differences in their behaviour as well.

The term “viral mutations” may strike fear among many. However, it is important to understand that many of these mutations are minute and do not necessarily cause increased virulence or transmissibility of the virus or more severe reactions in the patients. Some mutations may actually diminish the effects of the virus. Hearteningly, studies show that the Covid-19 viral mutation rate is slower compared to other RNA viruses similar to it.

However, it should be understood that Covid-19 is a relatively new virus infecting humans, and scientists and doctors are still studying the full length and breadth of its behaviour.

 

The double mutant virus: What is it?

 

India is currently going through a Covid-19 wave of massive proportions. Amidst that chaos, they have reported what is being tagged as the “double mutant virus”, which basically means that the particular strain shows two mutations compared to the original Covid-19 virus.

“The one reported in India is a combination of E484Q and L452R variants,” former All India Institute of Medical Sciences Medical Superintendent M.C. Mishra said.

Health experts say the L452R variant was first found in the US, whereas the E484Q variant is indigenous to India. And currently, these two mutations have come together in the new “double mutant strain”.

“Though VOCs (variants of concern) and a new double mutant variant have been found in India, these have not been detected in numbers sufficient to either establish a direct relationship or explain the rapid increase in cases in some states,” the Indian Health Ministry said.

Some 10,787 samples from 18 Indian states also showed up 771 cases of known variants – 736 of the UK variant, 34 of the South African variant, and one of the Brazilian variant.

The Indian Government said that an analysis of the samples collected from the western state of Maharashtra showed “an increase in the fraction of samples with the E484Q and L452R mutations” compared with December last year.

Indian officials are checking if the variant, where two mutations come together in the same virus, may be more infectious or less affected by vaccines.

The Indian SARS-CoV-2 Consortium on Genomics (INSACOG), a group of 10 national laboratories under India’s Health Ministry, carried out genomic sequencing on the latest samples. Genomic sequencing is a testing process to map the entire genetic code of an organism to study its possible behaviour and implications.

The genetic code of the virus works like its instruction manual. Mutations in viruses are common but most of them are insignificant and do not cause any change in its ability to transmit or cause serious infection. But some mutations, like the ones in the UK or South Africa variant lineages, can make the virus more infectious and in some cases, even deadlier.

 

Will it make the currently available vaccines redundant?

 

Indian virologist Dr. Shahid Jameel explains that a “double mutation in key areas of the virus’s spike protein may increase these risks and allow the virus to escape the immune system”.

The spike protein is the part of the virus that is used to penetrate human cells. And the vaccines train the human host cells to identify the Covid-19 spike protein and develop antibodies against the virus. However, if the Covid-19 spike protein undergoes significant mutations, it may cause “vaccine escape”, meaning it may make the currently available vaccines redundant.

However, new mutations are expected in a virus, and the World Health Organisation (WHO), COVAX, and scientists globally are keeping a close watch on new mutations and liaising with vaccine developers who are also gearing up to make necessary changes in vaccines if required.

However, what we should keep in mind is that the vaccines do not translate to a full stop to the current pandemic, and that we must remain vigilant and continue practising social distancing, wearing masks, sanitising, and avoiding overcrowding. The Covid-19 rollercoaster ride has not yet ended and we may face more twists and turns on the already bumpy ride.

 

(The writer is a medical officer currently attached to a government hospital. His experience spans across the medical profession as a medical practitioner, and across the pharmaceutical and surgical equipment industry. He also possesses an MBA and a Diploma in Economics. Having represented his university rugby team in international tournaments, he also has a special interest in sports medicine)