Proteins Behind Decreased Spread of Coronavirus Mutants in Asia: Studies

A deficiency of lung protective protein in the white population may have made Europe and North America more sensitive to the spread of coronavirus mutants compared to Asia, a study by Indian scientists suggests that the virus How to infect people who reveal how mutants may find new ones.

This study, published in the journal Infection, Genetics and Evolution, evaluated the worldwide spread of coronavirus variants with the D614G mutation, a major strain that infects populations in North America and Europe.

This variant spreads very rapidly, with more than 64.11% of globally infected individuals carrying the mutant virus from just 1.95% in January in just 10 weeks from February to March 2020. It was confirmed that.

However, researchers, including researchers at the National Institute of Biomedical Genomics (NIBMG) in Kariyani, West Bengal, said it took quite a long time for this subtype to reach 50% of its relative frequency in East Asia. (5.5 months). It took 2.15 months in Europe and 2.83 months in North America.

According to scientists, protein α-antitrypsin (AAT) deficiency throughout the European and North American populations is one of the main factors explaining the rapid spread compared to the transmission of this variant on two continents. It is one. Asia.

“In order for coronavirus to enter the cell, its peplomer binds to the ACE2 receptor in human cells, and the human enzyme TMPRSS2 cleaves at the junction of the protein’s two subunits S1 and S2, causing the virus to fuse with the cell. It makes it possible to do it. ” Study the corresponding author Nidhan KBiswas of NIBMG.

“But the D614G mutation in the peplomer has given the virus an additional cleavage site that allows it to fuse with the cell,” Biswas told PTI.

In coronavirus strains with the D614G mutation, the 614th molecule (aspartic acid) of the viral peplomer indicated by D is replaced by the glycine molecule indicated by G.

“Instead of one cleavage site, the mutant virus has two such sites that can be used in duplicate to make it easier to enter the cell,” Biswas explained.

Based on current studies, he said that this site of the virus is normally cleaved by the host protein neutrophil elastase, which is involved in the elimination of bacterial infections in the lungs.

Studies show that levels of elastase molecules in the body are naturally suppressed by AAT, whose main function is to protect the lungs from inflammation and tissue damage.

“The problem is that high neutrophil elastase also causes more damage to lung cells, so there is a balance mechanism mediated by the AAT enzyme that is naturally present in everyone’s lungs,” Biswas explains. Did.

Studies show that AAT deficiency is very prevalent in the population of Europe and North America, but much less in East Asia.

Specifically, Biswas said that AAT deficiency in the general population is very high in Italy and Spain.

He explained that a deficiency of this protein makes it easier for the neutrophil elastase molecule to act on the viral spike subunits, significantly speeding the spread of this mutant.

“The problem is that people with AAT deficiency have high neutrophil levels and when infected with the SARS-CoV-2 virus with the D614G mutation, cells can quickly take up the virus and invade the entire system. “NIGMB scientists explained. ..

Researchers believe that this finding, along with other social factors, may explain the difference in geographical / ethnic spread of the 614G.

While the findings provide clues about the transmission of viral variants, Biswas warned against the interpretation of studies on the severity and mortality of diseases caused by strains.

He also said the study provided some clues about the spread of other variants of the coronavirus, including those first reported in the United Kingdom and South Africa “built on the backbone of the D614G mutation.” ..

“Because the UK and South African variants also have the backbone of this mutation, they may have similar transmission patterns and perhaps additional features that scientists need to find. There is, “Biswas added.

However, he said further studies on cells cultured in the laboratory are needed to validate these conclusions.

Scientists believe that the findings open up the possibility of considering AAT supplements in the prevention of infection with the D614G subtype SARS-CoV-2 virus.

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