variant

Kolkata, April 21: After the B.1.617 “new mutant variant” was found in more than 60 percent of cases sampled for genome sequencing in Maharashtra, a new lineage of SARS-CoV-2 has been found in India.

B.1.618, the new variant, is characterized by a distinct set of genetic variants including E484K and is being called a major immune escape variant — that is it can escape immunity even if a person has contracted the virus before and has the ability to produce antibodies against it.

The proportions of B.1.618 have been growing significantly in West Bengal, scientists have pointed out.

Experts have suggested that the initial sequences in the B.1.618 variant were found in West Bengal, which is currently witnessing state elections. Moreover, members of this lineage have also been found in other parts of the world in the US, Switzerland, Singapore, and Finland. The variant was first found in a sample outside of India on April 22, 2020.

 

At least 129 of the 130 B.1.618 sequences in India were found in samples from West Bengal. Currently, India has 62.5 percent of the B.1.618 variants reported in the world, as per analysis on the outbreak info. However, the lineages found here do not have a full complement of variants as found in India, experts have said.

According to a Twitter thread by Vinod Scaria, a researcher at the Council of Scientific and Industrial Research’s Institute of Genomic and Integrative Biology (CSIR-IGIB) in New Delhi, E484K is a major immune escape variant — also found in several emerging lineages across the world. E484K can escape multiple mAbs as well as panels of convalescent plasma, meaning the infection through this variant makes plasma therapy, or plasma is taken from recovered Covid-19 patients and given to those who are infected with Covid-19, as redundant as an investigational treatment?

“While E484K is in the Receptor Binding Domain, Y145 and H146 are not part of the residues interacting with the Human ACE2 receptor. The structural impact of the 2AA deletion causes spike protein is yet to be understood completely,” said Dr. Scaria.

The B.1.618 along with B.1.617 form a major lineage of SARS-CoV-2 in West Bengal.

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“There are many unknowns about this lineage at this moment, including its capability to cause reinfections as well as vaccine breakthrough infections. Additional experimental data is also required to assess the efficacy of vaccines against this variant,” said Dr. Scaria.

“At this moment, there is no conclusive evidence that the lineage drives the epidemic in West Bengal, apart from the fact that the numbers and proportions have been significantly increasing in recent months. More focused epidemiological investigations would address these questions,” he said.

Data submitted from India to the global repository GISAID shows B.1.618, at 12 percent, is the third most common variant sequenced in the last 60 days. The B.1.617, at 28 percent, is the most common among sequences, followed by B.1.1.7 (the UK variant), the India Mutation A report by Scripps Research showed, citing the GISAID data.