Gene therapy gives protection from pandemic flu strains

Researchers from the Perelman School of Medicine, University of Pennsylvania, recently developed a new gene therapy to counter a potential influenza pandemic, which proved successful in clinical trials with mice and ferrets.

The study, led by James M. Wilson, Anna Tretiakova and Maria P. Limberis, was published this week in Science Translational Medicine. Researchers used a single dose of an adeno-associated virus, which administered broad, neutralizing flu antibodies in to the nasal passages and lungs. These antibodies protected the mice and ferrets completely from H5N1 and H1N1 influenza strains, including a strain from a pandemic flu outbreak in 1918.

Traditional methods of vaccine development use infected eggs to allow the flu virus to grow and mutate, then the hemagglutinin is removed and used as the vaccine. The virus mutates each year and new vaccines must be developed annually.

"Further development of this approach for pandemic flu has taken on more urgency in light of the spreading infection in China of the lethal bird strain of H7N9 virus in humans," Wilson said.

This new method used the AAV9 primate virus to target respiratory cell antibodies. Researchers believed if they could target antibodies in nasal and oral mucosa, where the influenza typically enters the body, they would have a fighting chance at protecting the body from infection.

In the trial, both mice and ferrets were exposed to lethal quantities of influenza strains. Mice were exposed to three strains of H5N1 and two strains of H1N1. In all trials, the animals were completely protected from infection with the new methodology.

"The novelty of this approach is that we're using AAV and we're delivering the prophylactic vaccine to the nose in a non-invasive manner, not a shot like conventional vaccines that passively transfer antibodies to the general circulation," Limberis said.

The technique isn't uncommon for treating cancer or autoimmune diseases, Tretikova explained, but it is a new method for treating infectious diseases.

"This novel technique has allowed for the development of a prophylactic passive vaccine that is cost effective, easily administered, and quickly manufactured," Tretikova said.

The team is currently working with stakeholders to develop the product rapidly as a way to both combat natural flu outbreaks and potential biological or chemical threats.

The research was supported in part by the National Institutes of Health, the Canadian Institutes of Health Research and ReGenX.

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