StemCell Therapy

A virus spreads by replicating itself each time it replicates, it could change a little. Mapping the genome of each changed form of the virus, therefore, helps track where it came from and how. The Translational Bioinformatics Group at the International Centre for Genetic Engineering & Biotechnology in New Delhi studied the genomes of the virus from five locations Wuhan, India , Nepal, Italy and the US to identify what is unique to the novel coronavirus and what difference geographical location makes. A country-specific mutation would explain the severity of illness, the extent and timing of exposure to symptomatic carriers and, consequently, hold the clue to a containment strategy. For instance, the study found the presence of unique mutations identified in the genome from Italy are responsible for the sudden upsurge in the number of affected cases and deaths, combined with other factors a speculation which may be verified with more evidence. Any strategy to counter the virus, then, would have to factor this in.Mutations help viruses survive in hosts and influence its virulence (how it attaches, infects and multiplies in a host). The mutations could be favourable or detrimental to the viruses, depending on the type of mutation. If a mutation results in a more virulent virus, its transmission is enhanced, Dr Dinesh Gupta, group leader of the study which published its preliminary findings in a preprint paper, told TOI.

Mutations help viruses survive in hosts and influence its virulence (how it attaches, infects and multiplies in a host). The mutations could be favourable or detrimental to the viruses, depending on the type of mutation

So what did they find? In the samples the group studied, the sequence from Nepal showed no variation at all. And the maximum mutations were seen in the Indian sequence, six. Mutations bring about variations in viral genomes as the virus evolves to survive in its host. A mutation may be good or bad. Very fast mutations produce viruses which are not able to survive. The viruses that do survive, adapt and transmit are the ones that are sequenced and analysed, Dr Gupta said.

Of the six mutations in Indian genome, only one was unique to India

Mutations in Indian genome

Spike surface glycoprotein (unique to India): A virus protein which helps a virus attach itself to a host cell and enter it

ORF1ab: Polyprotein which is cleaved to form 16 smaller proteins, each known as non-structural protein (Nsp)

Nsp2: Believed to hamper signalling process in host cell

Nsp3: Protein which breaks down other proteins

Helicase or Nsp12, unwinds DNA molecules

ORF8 protein: Helps virus in human adaptation

For specific conclusions, however, Dr Gupta said, a wider base of study would be needed. The current data of just two sequences from Indian samples is too small to make a definitive statement, and requires more sequences to be analysed. He also clarified that one finding of the preliminary report that the microRNA hsa-miR-27b (small RNA molecules that can influence the expression of virus proteins) was found to have a target only in the Indian genome in the first study could not be replicated. We didn't find any target for the miRNA hsa-miR-27b in the second sequence, whereas the miRNA was predicted to uniquely target the spike glycoprotein in the first sequence, he said.

Read more:
India What we know about the genome of the virus in India A mutation unique to - Times of India

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