Researchers identify possible immune targets in COVID-19 genome

Researchers studying the SARS-2 (COVID-19) virus have discovered potential target points on its genome, which may contribute to future treatments for the disease.

"Our work will contribute to a better understanding of how the virus escapes the host immune response and contribute to the development of attenuated viral vaccines," said study researcher Alex McLellan from the University of Otago in New Zealand.

The research team put into action their skills in microRNA (miRNA) gained from their usual topic of study of anti-cancer CAR T cells, to examine previously unrecognised weak points on the coronavirus genome that could be used to destroy the virus or help create new vaccines.

These weak points on the virus are target sites recognised by host miRNA -- a nucleic acid-based 'immune system' operating in all of our body's cells.

Essential for controlling gene expression within the cell, miRNAs are also important players in the recognition and destruction of viruses, the study, published in The International Journal of Molecular Sciences, reported.

One target site on SARS-2 matches an abundant miRNA (miR197) present in very high levels in patients with cardiovascular complications or with respiratory viral infections.

The miR197 binding site on SARS-2 had been independently mutated nearly 40 times since March this year.

This mutation is now present in more than 75 per cent of SARS-2 global isolates.

"Patients with cardiovascular complications have been shown to be at risk from Covid-19," McLellan said in a statement.

"Our study suggests that a normal defence pathway in these patients may have been blocked through this mutation in the virus," he added.

However, the researchers said that it is too early to say if such mutations will help the virus or are simply neutral hitchhikers that confer no advantage to the virus.The research team need direct experimental approaches using a live virus, as well as further study of the transmission of such mutants around the world.

According to the study, because many miRNAs are different between species, the newly emerged 'zoonotic' SARS-2 may be facing signature human miRNA attack, not previously experienced in bats.

The researchers said their findings also open up the possibility to engineer in artificial miRNA sites.

This may be useful for weakening the virus for vaccine research and has been successfully performed experimentally for other respiratory viruses, they wrote.

"Such strategies for the SARS-2 virus could contribute to worldwide vaccine efforts," the study authors concluded.