Ancient viruses brought back from the dead

  • 31/07/2015
Viruses evolved to efficiently transfer their genetic payloads into host cells (file)
Viruses evolved to efficiently transfer their genetic payloads into host cells (file)

Bringing a long-extinct virus back from the dead – it sounds like the start of a Hollywood techno-thriller, but scientists in the US think it could be the future of gene therapy.

Viruses evolved to efficiently transfer their genetic payloads into host cells, which makes them also very effective at delivering therapeutic genes for a variety of afflictions, such as haemophilia and inherited blindness.

But the current methods used involve naturally circulating viral strains, which many people are immune to because they've already been exposed.

So researchers in Massachusetts analysed amino acid sequences in current viruses used in therapy to work out their evolutionary lineage.

"Analysis of these evolutionary intermediates provides insights into how to uncouple important vector properties to build safer and improved gene therapy vectors," says author Eric Zinn of the Schepens Eye Research Institute.

This allowed them to construct synthetic versions of nine older viruses, which early tests on mice suggest could be more effective than current strains at delivering therapeutic gene therapy.

"The most ancient of those, named Anc80… successfully targeted the liver, muscle, and retina, with levels of gene transfer equivalent or superior to those of contemporary [viruses] used in clinical trials," the researchers said in a statement.

"Moreover, the ancestral virus did not produce any toxicity and was less susceptible to the immunity induced by [viruses] currently circulating in nature."

"Our work is the first demonstration of a computationally designed and fully synthetic viral vector for gene therapy," says senior author Dr Luk Vandenberghe of Harvard Medical School.

He says patients shouldn't fear the use of synthetic viruses – they can't replicate, and no previous viral gene therapy treatments have been known to cause disease.

"With the safeguards that have been put in place, we believe our contained approach to achieve a therapeutic gene delivery vehicle with beneficial properties and a distinct immunological profile to existing technology is not less or more unethical or dangerous as compared to other efforts to discover viral vectors."

The research is published today in journal Cell Reports.

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