Concerns had been raised after an increased frequency in the UK of this sub-lineage AY.4.2. (PTI File) WHILE DELTA is the dominant variant of SARS-CoV2 virus across the country, at least 18-20 sequences of the sub-lineage of the Delta – AY.4.2 — have been identified from over 19,000 samples collected from Kerala, Telangana, Andhra Pradesh, Karnataka and Jammu and Kashmir between May-end and mid- September this year.
Approximately 26 sequences from Asia (including Singapore, Japan, Bangladesh and Thailand) have been reported on GISAID — a global science initiative that provides open access to genomic data of influenza viruses and coronavirus responsible for the Covid-19 pandemic.
Experts at the Indian SARS-CoV-2 Genomics Consortium (INSACOG) said they have not noted any spike in Covid-19 cases due to AY-4.2. “AY.4.2 is very uncommon in India. The numbers are very low and not worrisome,” Dr Anurag Agrawal, director of CSIR-Institute of Integrative and Genomic Biology, told The Indian Express.
Concerns had been raised after an increased frequency in the UK of this sub-lineage AY.4.2. However it has not been categorised as a variant of concern by the World Health Organisation.
This descendant of the Delta (B.1.167.2) variant has two characteristic mutations in the spike Y145H and A2224.
According to reports of the UK Health Security Agency, the newly-detected variant AY.4.2 had accounted for 6% of all genetic sequences of SARS-CoV2 in the week beginning September 27.
Laboratory experiments on immune escape and other details will have to be studied to see whether this AY.4.2 is increasing or not and if at all (it is), then at what rate does it have the capability to take over Delta, said scientists.
However, experts at some labs under INSACOG said both the signature mutations for AY.4.2 were not found in several samples. “We have one of the mutations in some samples but not both and hence final updates are being worked on,” said a scientist.
Dr Rakesh Mishra, Director of Tata Institute for Genetics and Society at Bengaluru and former director of Centre for Cellular and Molecular Biology at Hyderabad, told The Indian Express.
“We have not noticed any such eruption in cases due to AY.4.2.This is a sub-lineage of Delta and is defined by certain number of mutations. However, not all these changes have been found in the samples that have been sequenced. We are seeing a small number of AY.4.2 but there is no particular reason to worry.”
INSACOG is a joint initiative by the Union Health Ministry, Department of Biotechnology with Council for Scientific and Industrial Research and Indian Council of Medical Research. It is a consortium of 28 national laboratories to monitor genomic variations in SARS-CoV2.
When contacted, state Surveillance Officer Dr Pradeep Awate said that there have been several sub-lineages or deviations in the Delta variant from AY.1 to AY.37.
“We are constantly monitoring whether these deviations are genetically different or whether they have the capability to replace the entire Delta variant… as of now, it is not of epidemiological importance,” said Dr Awate.
Meanwhile, the Maharashtra Directorate of Medical Education and Research has tied up with CSIR-Institute of Integrative and Genomic Biology (CSIR-IGIB) for genome sequencing of samples from across 36 districts , various institutions have come together to set up a Pune consortium as well.
Dr Anu Raghunathan, senior scientist at NCL, said they have not detected AY.4.2 in Pune and adjoining regions. “The Delta variant is still dominating, followed by the sub-lineage AY.4 Continued surveillance in real time among newly-infected, re-infection and vaccine breakthroughs are critical…”.
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