BENGALURU: The B.1.617 variant of the Covid-19, known more commonly as the double mutant strain, was first detected in India in October last year. As the name suggests, the strain involves two variants of the virus.
The E484Q mutation has characteristics of a previously detected variant - the E484K - which was seen in the fast-spreading Brazilian and South African variants, making it highly transmissible.
The L452R mutation, on the other hand, helps the virus evade the body’s immune response. The double mutation strain was subsequently named B.1.617.
The “double mutant” variant of SARS-CoV-2 virus, first found in October 2020 in Mumbai a few months ago, is not only appearing to overtake other variants across Karnataka but has also been declared a “Variant of Concern (VoC)” by the World Health Organisation (WHO) .
The “double mutant” -- also known as B.1.617 -- has been found in 147 samples tested for genome sequencing in Karnataka, experts said.
Dr Vishal Rao, Head and Neck Oncologist at HCG Hospitals and also part of Covid Technical Advisory Committee, said, “The B.1.617 is clearly a VoC and it is contributing significantly to the second wave that we are currently witnessing."
"There are more than 8,000 variants yet to be categorised.” Experts said that a mutant is categorised as VoC when mutations in Receptor Binding Domain (RBD) — the spike protein of SARS-CoV-2 virus — significantly increases the capability to bind with the receptor human cells, which is directly linked to the speed of infections among humans.
Dr Giridhara Babu, Professor, Indian Institute of Public Health, and Advisor, Covid Technical Advisory Committee, said, “Evidence from the UK suggests that the B.1.617 strain is more contagious compared to the Wuhan strain. Studies in India by INSACOG are under way to examine infectiousness and virulence of the variants. Although preliminary studies suggest that b o th the vaccines in India are effective against the newer variant, we need to wait for evidence for conclusive inference on these properties of the virus.”
Dr V Ravi, retired head of the Department of Virology Lab at NIMHANS and nodal officer, Indian SARS-CoV-2 Genome Sequencing Consortia (INSACOG), said, “An earlier study had found that B.1.1.7 (aka the UK variant) was the major lineage imported into Karnataka, followed by B.1.36 which was first reported in Saudi Arabia. Besides, B.1.1.74 and B.1.468 too are major variants circulating in Bengaluru city. But now we are seeing B.1.617 overtaking these other variants. As of now there are no other Variant of Concernss found, but more genome sequencing needs to be done.”
Apart from the double mutation (from which it got its referral name as ‘double mutant’), the B.1.617, just like other new variants, contains more than a dozen mutations, Dr Ravi explained.
“Of the 696 samples tested so far at the NIMHANS lab, we have found 147 samples with the B.1.617 variant,” he confirmed.
This resilient variant has been found in at least 21 countries, including the UK, the US and Singapore.
It is because of this resilience that private and government hospitals have been seeing several patients getting reinfected even after two doses of vaccination.
Dr CN Manjunath, Director, Jayadeva Institute of Cardiovascular Diseases, and member of Technical Advisory Committee, said, “The B.1.617 seems to be a major contributor to not just increase in new infections, but also resisting antibodies generated by vaccination or by natural infection.”
Dr John Jacob, a renowned virologist, said that as long as the number of cases is less, mutations will be lesser.
“The more the virus is replicating and spreading and transmitting, chances are that more mutations will develop and adapt. Variants which accumulate a lot of mutations may ultimately become resistant to current vaccines we have,” he added.
Experts are concerned that there is not much scientific data except a recent study by the Indian Council of Medical Research (ICMR)-National Institute of Virology which says that Bharat Biotech’s Covaxin has demonstrated potential effectiveness against the Indian variant too.