The strain of the novel coronavirus in a majority of cases in India is the predominant subtype found in other parts of the globe, a uniformity that bodes well for the efficacy of a vaccine or drug developed anywhere in the world, says a top scientist. Centre for Cellular and Molecular Biology Director Rakesh Mishra added that detailed gene mapping of the coronavirus also indicated that it is unlikely that it will mutate into a more dangerous strain. His institute has submitted 315 genomes on viral genome sequence repositories of the coronavirus and analysed over 1,700 publicly available virus sequences that were sampled across the country,

The virus is mutating at a rate of 26 times per year (once every 15 days) which is in accordance with the rate observed globally as it hints at the stability of the virus. The chances that existing clades (subtype) of the virus mutate into something more dangerous are very less, Mishra told PTI. So far, the mutations analysed in our data also suggest the same thing – they are either neutral or deleterious (for themselves), and therefore result in a weaker virus. Further sequencing of new samples will thus play an important role in understanding the course the virus takes, and its implications in vaccine development and cure, Mishra said.

Analysis of genome sequences done by the CCMB, a Hyderabad-based institute under the Council for Scientific and Industrial Research, has revealed the presence of two major subtypes (clades) in India – the A2a clade and A3i clade. A clade is a cluster of closely related genomes which share a common ancestor. These clusters are formed by the presence of the same sequence variation (mutation) across genomes falling within a particular cluster. Mutations are important because it could have implications in viral infectivity and pathogenicity.

Genome sequencing is figuring out the order of DNA nucleotides, or building blocks. It helps in understanding how genes work together to direct the growth, development and maintenance of an entire organism. According to Mishra, the A2a clade, also the most predominant strain globally, accounts for 80-90 per cent of the genomes from India right now. This uniformity of dominant clades in India and globally is good because if an efficient vaccine/drug is developed anywhere around the globe, it will work with the same efficacy even in our country, Mishra explained

The other major clade, A3i, which was identified by the CCMB and Institute of Genomic and Integrative Biology, accounted for 25 per cent of the genomes from India. However, it now accounts only 2-3 per cent in the samples sequenced, Mishra said. This clade is characterised by four mutations, Mishra said. Though it was more prevalent in earlier days of the pandemic (late March to mid- April), recently there is a reduced representation of this clade in all Indian states, except Delhi where this subtype was prevailing even as late as June. This is in line with our earlier suggestion that A3i could be a weaker clade, Mishra said.

The percentage of the strain is also coming down in Delhi, he added. The A3i strain is mostly found in Southeast Asia. In India, it was predominantly found in those infected in Tamil Nadu and Telangana. COVID-19 has infected more than 1,52,57,287 people across the globe and over 6,28,240 people have died due to it. In India, the virus has infected more than 12,87,000 and claimed the lives of 30,000 patients.