Possible Reasons for Emergence of Omicron Variant

Jay Kakade
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Virus

When a virus undergoes changes in its mutation it is called a Variant. Alpha was the first variant of SARS-CoV-2 that was declared a variant of concern.

In November 2021, Researchers discovered a new variant Omicron. Arrival of Omicron was more like a surprise for researchers. Not because of a new variant but due to its 50 mutations. Such a phenomenon is very rare and is not seen before.

Arrival of Omicron made scientists research on what caused Omicron to evolve in such a tremendous way, from where it exactly originated.
Some researchers think it might have evolved from a person whose immune system was good enough to challenge the existence of SARS-CoV-2. While some states it might have hosted animal cells and evolved and again entered human cells.

Virus undergoes mutations as it transfers from person to person by producing genetic errors as its multiples. Mutation can also be initiated if a virus is given a survival advantage by making it more transferable or able to penetrate the immune system.
This may result in the introduction of a new variant. If this process keeps on going, it gives rise to more powerful threats.

Studies and analysis of the genome suggests that SARS-CoV-2 typically undergoes two mutations per month. Researchers state this rate of mutation remains almost constant. After the period of 18 months of SARS-CoV-2, the virus may have undergone 36 mutational changes.
But Omicron shows more than 50 changes in its mutation. Out of 50 mutations, 30 are from spike proteins. Viruses use these Spikes proteins to enter and infect host cells.

Evolution through Immunocompromised People

Over the course of two years, Reports show some people have been infected by viruses and persist for months to years. In the presence of a weak immune system, Virus keeps on multiplying and mutating, which changes its appearance.
This is a reason viruses have infected people who have already suffered from corona by evading antibodies.

When a virus is composed of a host with a weak immune system, it tends to quickly multiply and undergo more mutations than expected. New genetic mutations tend to emerge if the host is unable to swipe out new viruses. When a virus undergoes mutations, weak genetic codes are accumulated under low immunity. These new and old genetic codes help viruses to survive.

To support given statements, In South Africa virologist Tongai Maponga recorded 20 mutations in the corona variant which infected a HIV positive. 20 mutations have evolved over a time period of nine months.
Likewise, the same happened in the U.K. where more mutations were recorded in patients suffering from advanced HIV.
In Portugal, High number of mutations were recorded when a cancer patient was infected by SARS-CoV-2 for six months. As this patient was treated with antiviral drug Remdesivir which weakened immunity. Such conditions provided a good opportunity for viruses to mutate.
After studying SARS-CoV-2 in the weak immune system, scientists think it may be a reason for the origin of Omicron.

But still we do not know possible reasons for Omicron emergence, how it is able to infect large numbers of populations. In addition, we don't know why some people are infected even if they show no symptoms.

Read More: Alien Invasive Species may harm biodiversity and agriculture in Africa

Evolution through Animal Host

Some theories suggest Omicron might have evolved from an animal host. More likely from mice or rats. There are some cases in which viruses have infected animals like Tiger, Hyena, Cats and Dogs too.

Though mice might not be a good host for SARS-CoV-2 as the proteins of the mice cell surface blocks the virus from entering. But new variants show mutations on spikes proteins which allow them to enter mice cells too. These adaptations are seen in Omicron too. There are more mutations in viruses which may be in response to rodent’s adaptations.

According to some Chinese virologists, The mutational patterns seen in Omicron are way different if it was an evolved human cell. Omicron shows mutations in uracil too.
But this Chinese virologist refuses to claim any animal from which it might have evolved.

There is a possibility that the virus was transferred to an animal by COVID infected patient and again a human got infected by coming in contact with COVID positive animal.

Still, many scientists believe in the theory of origin from immunocompromised people. Researchers are now closely monitoring SARS-CoV-2 in HIV positive patients. While another group will be monitoring domestic animals like horses, dogs and cats.

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