Kolkata: A global study done by two Indian scientists has found that the novel coronavirus has mutated into 10 different types, with one of them replacing the other strains of the virus rapidly across geographical regions, including India. The A2a has emerged as the dominant strain worldwide by March-end, taking over from the other 10 types of the virus, said the study.
The study conducted by Partha Majumder and Nidhan Biswas from the National Institute of Biomedical Genomics (NIBMG), Kalyani, West Bengal, would help in the fight against COVID-19 which currently has no cure. The findings may help researchers in developing vaccines as well as determining the presence of co-existence of type A2a with other types in some regions.
The scientist analysed the genome sequence of the type A2a strain and found that a specific mutation with the strain enables the A2a virus to be highly efficient in entering human lung cells, perhaps, in larger numbers as compared to other types. According to the authors, the SARS-CoV-2 virus with A2a mutation is systematic in transmission and as a consequence, COVID-19 spread rapidly across the world.
Initially, India and many other countries received the ancestral O type from China, however, the virus acquired mutations and evolved into 10 different strains over time, and with the A2a replacing other types in most countries. This means the new 10 types have evolved from the earliest type ‘O’ from China.
“The coronavirus can be classified into many types – O, A A2a, A3, B, B1, and so on. Currently, there are 11 types, including type O which is the ‘ancestral type’ that that originated in Wuhan,” professor Majumder, who is also founding director of the institute, was quoted as saying by TOI.
“To live, a virus must propagate by infecting other animals. A mutation usually disables the virus from transmitting itself said Majumder. However, some mutations enable the virus to transmit more efficiently and infect more persons. “Such mutant viruses increase the frequency (of transmission) and sometimes completely replace the original type of the virus. The SARS-CoV-2 is doing just that,” he added.
The scientists discovered that the A2a mutation also caused a change in the makeup of the spike protein, easily allowing it to cling to other surface protein of the lung cell. The novel coronavirus uses spike protein to infect a cell.
For the study, the scientists used RNA sequences of more than 3,600 coronaviruses collected from 55 countries beginning December 2019 till April 2020. They also accessed the RNA sequence data in a public database called, GISAID, shared by researchers from across the world studying the SARS-CoV-2 virus.
A small sample of RNA sequences taken from COVID-19 patients in India showed that the A2a type accounted for 47.5 per cent of samples, said the study. The researchers also found that many people with type A2a have no known travel history to foreign countries. The scientists, however, noted that more samples of RNA sequences are required before coming to a conclusion on whether the A2a type is the most common strain in India.
The findings, which will be published in the Indian Journal of Medical Research, a peer-reviewed journal published by the Indian Council of Medical Research, could help researchers in their efforts towards finding a vaccine against coronavirus. Till date, the novel coronavirus has claimed at least 206,567 lives and infected more than 2,961,540 people in 193 countries and territories.