Scientists from National Institute of Biomedical Genomics (NIBG), Kalyani have found the biological mechanism behind the significantly faster spread of Coronavirus in Europe and North America but not in East Asia. According to them the main reason behind the slow spread of mutant Coronavirus in Asia compared to the West is due to the deficiency of a particular human protein.
The scientists explained to Times of India how higher levels of a human protein- neutrophil elastase-helps virus to enter human cells, multiply, and also spread faster from COVID-19 infected patients.
However, this protein is kept in check by the biological system, which produces another protein call alpha-1 antitrypsin (AAT). So, AAT deficiency leads to higher levels of neutrophil elastase in the cells, which helps the SARS-CoV-2 to spread more quickly.
The scientists noted the deficiency of AAT is much higher in Europe and America than among Asians. The study has been published in the journal, Infection, Genetics, and Evolution.
The team of scientists including Nidhan Biswas and Partha Majumder said that naturally occurring mutations in the AAT-producing gene result in the deficiency of the AAT protein. The results of their study are published in the journal Infection, Genetics and Evolution.
“Compared with Asians, we found a large proportion of Caucasians in European countries and North America carry natural mutations in the gene that leads to deficiency in AAT production,” says Dr. Majumdar. “This is the reason why the variant spread widely in Europe and North America but not in Asia.”
According to the paper, at 18.7 per 1,000 individuals, the AAT deficiency is the least in Poland while in Portugal as many as 75.9 per 1,000 individuals have AAT deficiency. Spain has the second highest deficiency of AAT protein at 67.3 per 1,000 individuals while it is 51.9 per 1,000 individuals in the case of France. Canada and the U.S. have 32.1 and 29 per 1,000 individuals with the protein deficiency, respectively.
In contrast, in the case of East Asia, Thailand has the highest at 19.9 per 1,000 individuals while it is just 8 and 5.4 per 1,000 individuals in Malaysia and South Korea, respectively.
Earlier, the most popular speculation of different behaviour of COVID-19 in East and West was the higher temperature in Asia, Majumder said. He added, “We believed the cause had to be biological rather than physical or social”.
However, the researchers emphasised that their findings along with other social factors might explain the differential geographical or ethnic spread of the coronavirus.