REVIEW: Covid-19 Virus Variants And Effects
REVIEW: Covid-19 Virus Variants And Effects

REVIEW: Covid-19 Virus Variants And Effects

In this study, we are talking about dominant mutation types of sars-cov-2 and how it affects current treatment
In this study, we are talking about dominant mutation types of sars-cov-2 and how it affects current treatment

Viruses (including sars-cov-2) can be affected by the environment and develop their abilities. So, they can be more dangerous or less harmful.

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Research by Hatice Gül FAZLIOĞLU

The average evolutionary rate of SARS-CoV-2 is equals about 2 substitutions (“mutations”) per month. Generally, many mutations are essentially neutral, and are maintained in the population: they may not readily promote functional changes. A few mutations may be beneficial to the virus because they lead to; increased transmissibility, higher infectiousness, higher virulence entailing higher rate of severe disease, immune / vaccine escape or any combination of the above.

SARS-CoV-2 variants identified are heterogeneously distributed in geographic areas of the world. Some mutations may increase in frequency, either through genetic drift or through selection, and become fixed in different populations. The variant B.1.1.7 (those that changes the asparagine residue at spike position 501), was announced in the South East of England on December 14, 2020. Rapidly spreading variants were also detected in South Africa.

Viruses belonging to the lineage B.1.351 were detected in December 2020. After the detection of these variants harboring similar genetic changes, genomic surveillance in countries experiencing high COVID-19 incidence started to report more variants with convergent genetic traits.

In this study, we are talking about dominant mutation types of sars-cov-2 and how it affects current treatment.

New Variants of the Covid 19

Viruses can be affected by the environment and they can develop abilities. Thus, they can be more dangerous or become less harmful.

“All RNA viruses mutate over time, some more than others. For example, flu viruses change often, which is why doctors recommend that you get a new flu vaccine every year.” Robert Bollinger.

Mutations in viruses (including the coronavirus causing the COVID-19 pandemic) are neither new nor unexpected. Nevertheless, this situation cause of concern for all countries is the emergence. RNA viruses, such as SARS-CoV-2, despite being endowed with ”proofreading” activity during viral replication, have a high mutation rate, and the absolute number of mutations increases with every round of infection.

The average evolutionary rate of SARS-CoV-2 is equals about 2 substitutions (“mutations”) per month. Generally, many mutations are essentially neutral, and are maintained in the population: they may not readily promote functional changes. However, they may facilitate adaptation upon changes in the environment explored by viruses. A few mutations may be beneficial to the virus because they lead to;

  1. İncreased Transmissibility
  2. Higher İnfectiousness
  3. Higher Virulence Entailing Higher Rate Of Severe Disease
  4. İmmune / Vaccine Escape;
  5. Or Any Combination Of The Above

New Variants Of Sars-Cov-2 Virus

Up to March 31, 2021, nearly 1 million SARS-CoV-2 genomic sequences were submitted to the GISAID, the main database used by researchers in the field. SARS-CoV-2 variants identified are heterogeneously distributed in geographic areas of the world. Variants of SARS-CoV-2 may adapt differently to the host under individual selective pressures; some mutations may increase in frequency, either through genetic drift or through selection, and become fixed in different populations.

This is the case of the mutation that led to the amino acid change (D614G) in the spike glycoprotein (S), found in the predominant form of SARS-CoV-2. This appears to make some of these new strains ‘stickier’ due to changes in the spike protein. Patients infected with the D614G variant often have higher viral loads in the upper respiratory tract than seen with the ancestral strain, but there seems to be no difference in disease severity.

Sars-Cov-2 Variants And Their Origins

Many SARS-CoV-2 mutations appeared and were selected for several times, independently, e.g., those that changes the asparagine residue at spike position 501 (B.1.1.7). The variant B.1.1.7, was announced in the South East of England on December 14, 2020. Rapidly spreading variants were also detected in South Africa. Viruses belonging to the lineage B.1.351 were detected in December 2020. After the detection of these variants harboring similar genetic changes, genomic surveillance in countries experiencing high COVID-19 incidence started to report more variants with convergent genetic traits.

In late 2020, a new variant was detected in Manaus, state of Amazonas, northern Brazil. The P.1 lineage was identified in 42% (13 of 31) of RT-PCR positive samples collected between 15 and 23 December 2020. Finally, two lineages originated in California, USA, have also emerged and increased in frequency from late 2020 to early 2021, named B.1.427 and B.1.429. Variants from these two lineages have higher transmissibility (from 18.6 to 24%) when compared with wild type variants.

Some of the variants of concern have not only been associated with increased transmission potential but also with reduced susceptibility to neutralizing antibodies from convalescent patients and vaccines. However, it is important to point out that cellular response conferred by vaccines is robust, identifies epitopes from many proteins beyond the Spike. Major losses of vaccine efficacy would mainly come as a cumulative effect of several widespread genetic changes that SARS-CoV-2 undergoes as it continues to spread.

Covid-19 Vaccine Work on Variants?

Stuart Ray says, “There is new evidence from laboratory studies that some immune responses driven by current vaccines could be less effective against some of the new strains.” The immune response involves many components, and a reduction in one does not mean that the vaccines will not offer protection.

“People who have received the vaccines should watch for changes in guidance from the CDC [Centers for Disease Control and Prevention], and continue with coronavirus safety precautions to reduce the risk of infection, such as mask wearing, physical distancing and hand hygiene.”

“We deal with mutations every year for flu virus, and will keep an eye on this coronavirus and track it,” says Bollinger. “If there would ever be a major mutation, the vaccine development process can accommodate changes, if necessary,” he explains.

We know that viruses can change their nature and abilities, and this can be more dangerous or less harmful. Research on Covid-19 says the “mutant virus” is not dangerous for us for now. We can say, current vaccination studies are not affected by the mutant virus, too.

Conclusion

We talked about that viruses can be affected by the environment and they can develop abilities. Thus, they can be more dangerous or become less harmful. These mutations are neither new nor unexpected. Generally, many mutations are essentially neutral, and are maintained in the population: they may not readily promote functional changes. SARS-CoV-2 variants identified are heterogeneously distributed in geographic areas of the world.

One of the mutation that led to the amino acid change (D614G) in the spike glycoprotein (S), found in the predominant form of SARS-CoV-2 appears to make some of these new strains ‘stickier’ due to changes in the spike protein. Patients infected with the D614G variant often have higher viral loads in the upper respiratory tract than seen with the ancestral strain, but there seems to be no difference in disease severity. The variant B.1.1.7 (those that changes the asparagine residue at spike position 501) , was announced in the South East of England on December 14, 2020.

In late 2020, a new variant was detected in Manaus, northern Brazil. Finally, two lineages originated in California, USA, have also emerged and increased in frequency from late 2020 to early 2021, named B.1.427 and B.1.429. Variants from these two lineages have higher transmissibility when compared with wild type variants. This is an example when the mutation is handled in favor of the virus. Thus, some of these variants have remained insensitive to vaccines. Therefore, vaccinated people should be followed for a while and should continue to apply the pandemic rules without interrupting.

However, we must consider the discovery of a different and more harmful variant at a later date, too. Perhaps a different variant could make the covid-19 disease more deadly, infectious. There may even be a different disease with different symptoms. Therefore, this situation can directly affect the studies of existing vaccines. Fortunately the mutations finded do not appear to affect the vaccine studies for now.

Discussion

We mentioned that mutations can affect the virus very differently. I am wondering if more dangerous mutation is find, are there worse days waiting for us? Or can sars-cov-2 virus disappears suddenly? Maybe scientists can find a mutation that makes the disease less harmful. For all that there may also be a variant with much worse effects. In this case, more attention should be paid to the studies on virus variants and these studies should be accelerated. Perhaps developing molecular technologies can facilitate this situation.

Fortunately, virus variants found so far are not dangerous. Although we can say that the contagiousness of the covid-19 disease has changed in line with the above mentioned, this does not seem like a huge disaster for now. What we fear is the virus moving towards severe destruction. We hope that the sars-cov-2 virus could mutate to disappear completely or become harmless. Even, maybe the virus can change its host or become an ordinary flu. If we think the worst case scenario, perhaps biotechnological advances could produce a vaccine to which many variants of the virus are susceptible. Our hope now in this direction.

Research by Hatice Gül FAZLIOĞLU