The ‘double mutant’ virus making headlines recently concerning the spread of the Covid-19 pandemic in India has been formally classified as B.1.617. A mutation refers to a change in the genetic material (the genome) of a cell in a living organism or a virus that is somewhat permanent and can be transmitted to the cell’s or the virus’s descendants.
Double Mutant (B.1.617): The Discovery
The Indian SARS-CoV-2 Consortium on Genomics (INSACOG) carried out Genome sequencing of a section of virus samples. This revealed the presence of two mutations, E484Q and L452R. Though these mutations have individually been identified in different countries, the simultaneous presence of both these mutations was first discovered in coronavirus genomes from India. This ‘double mutant’ has been scientifically named B.1.167. The term ‘Variant of Concern’ has not yet been applied to this mutant.
Global ‘Variants of Concern’
Currently, the world recognizes three global ‘Variants of Concern’: the U.K. variant (B.1.1.7), the South African (B.1.351) and the Brazilian (P.1) lineage. These variants show evidence of increased transmissibility, severer disease, significant reductions in neutralisation by antibodies formed during previous infection or vaccination, reduced effectiveness of treatments or vaccines, or diagnostic detection failures.
The Spread of B.1.617
In India, the B.1.617 variant was first detected in December 2020, according to INSACOG sample sequencing. Presently, nearly 70% of the genome sequences with the mutations characterizing B.1.617 are from India, followed by the United Kingdom (23%), Singapore (2%) and Australia (1%).
Challenges Associated with Virus Mutations
A mutant virus can trigger large Covid-19 spikes in some countries. It can elevate the virus’s infectiousness and help it evade antibodies. This mutation is also linked with a reduction in vaccine efficacy. International studies have shown reduced efficacy of vaccines, particularly those by Pfizer, Moderna and Novavax to certain variants. Despite this challenge, the vaccines continue to offer significant protection.
More on Mutations: P614R
INSACOG suggests that there is another significant mutation known as P614R aside from the two mutations E484Q and L452R. All three potentially concerning mutations are located on the spike protein, the part of the virus that invades human cells. This mutated virus’ spike protein may increase risks and enable the virus to escape the immune system.
The Role of T Cells
The mutation L452R could make the coronavirus resistant to T cells, which target and destroy virus-infected cells. T cells operate differently from antibodies that work to block coronavirus particles and prevent it from multiplying. T cells are a type of white blood cell crucial to the immune system, forming the body’s adaptive immunity. They act like soldiers who seek out and eliminate the specific pathogens.
About INSACOG
The Indian SARS-CoV-2 Consortium on Genomics (INSACOG) is a pan-India network involving multiple laboratories and agencies to monitor genomic variations in the SARS-CoV-2. Its goal is to better understand how the virus spreads and develops. Genomic surveillance can produce a wealth of data for tracking pathogen transmission and evolution on both national and international levels.