NIMHANS study could serve as benchmark for existing Covid-19 lineages, genomes: Expert

Researchers from Karnataka used a combination of contact tracing and genomic epidemiology to trace the spread of SARS-CoV-2 in the state up until May 21, 2020.

They obtained 91 genomes of SARS-CoV-2 which clustered into seven lineages. These findings were published on December 17 and are significant especially in the context of a new strain of the virus emerging in the UK.

The lineages in Karnataka currently are known to be circulating in China, Southeast Asia, Iran, Europe and other parts of India and are likely to have been imported into the state both by international and domestic travel, researchers found.

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Genomic epidemiology of SARS-CoV-2 in Karnataka suggests multiple introductions of the virus followed by local transmission in parallel with ongoing viral evolution. This is the first study from India combining genomic data with epidemiological information, claim the researchers in their paper.

This work was supported by core funds of NIMHANS to the Department of Neurovirology and was done in collaboration with the state Health Department.

A 20-member team authored the research article led by Dr V Ravi, HOD, Neurovirology, NIMHANS. In the paper titled 'Genomic epidemiology reveals multiple introductions and spread of SARS-CoV-2 in the Indian state of Karnataka', researchers said, "Of the 91 sequences, 47 belonged to the B.6 lineage, indicating ongoing transmission of this lineage in the state...

...The index case of the largest cluster in the state (Nanjangud), initially restricted to Mysuru that subsequently spread to Vijayapura and Mandya, had no history of international travel but was an employee of a company which had a number of international visitors until mid-February 2020, including visitors from Europe. The presence of two lineages is indicative of multiple introductions of the virus in this cluster."

Epidemiologist Dr Giridhar Babu said, "This study gives a clear picture of whichever lineages were present in the state during the early part of the pandemic. We need to do targeted genomic sequencing of samples with relevant correlations like international travel history and symptoms. This provides a benchmark for what existed then and now, which can be compared with further genomic sequencing of samples of those who come from abroad. Not many states in the country will have this kind of evidence."

"More than 4,000 nucleoid changes have been seen in the SARS-CoV-2 virus so far but only a few amino acid changes. Only when the amino acid changes, the protein structure changes. Whenever an outbreak happens with more cases of a particular strain, a correlation can be made with the existing evidence," he added.