IISc team finds new mutations and proteins of SARS-CoV-2

Analysis suggests that the virus is now mutating faster than before

A team of researchers from the Indian Institute of Science (IISc.) has identified multiple mutations and unique proteins in isolates of SARS-CoV-2, the virus that causes COVID-19.

This study, published in the Journal of Proteome Research , has also shown that the hosts produce several proteins of their own as their body launches an immunological defence in response to the viral attack.

Genomic analysis

To better understand how the virus is mutating and its protein biology (proteins are made using genetic information), an IISc. team led by Utpal Tatu, Professor in the Department of Biochemistry, carried out a comprehensive “proteo-genomic” investigation – a series of analyses of SARS-CoV-2 isolates. The isolates or viral samples were recovered from nasal secretions of three consenting COVID-19 RT-PCR positive individuals in Bengaluru.

The genomic analysis was done using next generation sequencing (NGS), a technology that allows for rapid sequencing of the entire genome. The three Bengaluru isolates had 27 mutations in their genomes with over 11 mutations per sample, more than both the national average (8.4) and global average (7.3).

Why it is important

According to Prof. Tatu, sequencing the genomes of viral strains from around the world is important because it helps keep track of mutations that are arising constantly. His team’s analysis suggests that the virus is now mutating faster than before.

To understand the spread and evolutionary history of the virus, the team constructed a global phylogenetic tree, or a tree of relatedness, of viral isolates using the sequence data. The phylogenetic analysis found that the Bengaluru isolates are most closely related to the one from Bangladesh. It also showed that the isolates in India have multiple origins rather than having evolved from a single ancestral variant.

Detection of proteins

The SARS-CoV-2 genome codes for more than 25 proteins, but only a handful of these proteins have been identified so far. In the proteomic analysis, his team detected 13 different proteins – most of them previously unidentified – from clinical samples. One such protein called Orf9b, which suppresses the host’s immune response, had been predicted, but the IISc team provided the first evidence of its expression.

In the third analysis, his team explored how our bodies respond to the virus by examining host proteins. They discovered as many as 441 proteins unique to COVID-19 positive patients, many of which are speculated to play a key role in the body’s immune response.