HYDERABAD: The Delta variant (B.1.617.2), first discovered in India, has now acquired a new mutation to emerge as Delta+ (B.1.617.2.1).
Also called AY.1 the Delta+ (Delta plus) mutant has acquired K417N mutation.
Scientists fear that the monoclonal antibodies cocktail currently prescribed for Covid-19 patients may not work against the Delta+ mutant.
According to Public Health England (PHE), a UK government public health body, 63 genomes of Delta with K417N mutation have been identified on GISAID.
In its latest report on Covid-19 variants updated on June 11, India has reported six cases of AY.1 or Delta+ as of June 7.
Dr Vinod Scaria, clinician and computational biologist, Institute of Genomics and Integrative Biology (IGIB), New Delhi, while referring to the Delta+ variant said: “One important point to consider regarding K417N is evidence suggesting resistance to monoclonal antibodies Casirivimab and Imdevimab.
The monoclonal antibodies (mAb) cocktail incidentally has received an emergency use authorisation (EUA) from the Central Drugs Standard Control Organisation (CDSCO) in India.” Dr Vinod tweeted on Sunday that one of the emerging variants is B.1.617.2.1 also known as AY.1 characterized by the acquisition of K417N mutation.
The mutation maps to the receptor binding domain and has also been associated with immune escape.
“The variant frequency for K417N is not much in India at this point in time.
As Delta continues to evolve acquiring new mutations, there is a lot of interest in understanding these mutations,” Dr Vinod tweeted, naming the new mutant as Delta+.
Earlier, a report by PHE said the Delta-AY.1 (Delta with K417N) was found through routine scanning of variation in Delta.
A small number of sequences were detected which had acquired the spike protein mutation K417N.
Scientists attribute the earliest sequence from Europe in late March 2021.
Dr Vinod said 127 sequences from Europe, Asia and America are now available in public domain.
“Understanding this continued evolution is of great importance in mapping the evolutionary landscape of emerging variants.
Largely, the virus has tried to optimise for transmission and immune escape by step-wise acquisition of new mutations,” he added.
He said several genomes are now available for the lineage AY.1 or B.1.617.2.1 from across the world.
The sequences are mostly from Europe, Asia and America.
The travel histories are not readily available to make assumptions.
“The novel coronavirus has a nearly constant rate of acquiring genetic variants.
Each emerging variant has acquired additional variants in a stepwise fashion.
Acquisition largely follows a trend of transmissibility and/or immune escape.
The K417N mutation is also found in Beta or B.1.351, which is also regarded as the variant of concern.
Delta+ cases were also reported from other countries.
They include one case each from Canada, Germany and Russia, two from Nepal, four from Switzerland, nine from Poland, 12 from Portugal, 13 from Japan and 14 from the USA.