Gene Therapy May Protect Against Flu Pandemics

Study found coaxing cells in the nose to make super antibodies protected mice and ferrets from pandemic strains

By Brenda Goodman

HealthDay Reporter

WEDNESDAY, May 29 (HealthDay News) -- Gene therapy that turns cells in the nose into factories that crank out super antibodies against the flu protected mice and ferrets against lethal doses of several pandemic strains of the virus.

If the approach works in humans, it could offer several important advantages over flu vaccines, said study author Dr. James Wilson, a professor of pathology and laboratory medicine at the University of Pennsylvania, in Philadelphia.

Because the therapy can be made ahead of time and fights many different strains, it might give doctors a faster way to thwart flu pandemics.

Currently, doctors race to identify dangerous new types of flu. They then have to develop a vaccine that targets the new strain. The vaccine is then grown in chicken eggs and tested for safety. It takes between three and six months to manufacture large quantities of vaccines against the flu.

"By the time we realize it's a potential pandemic, it's too late," Wilson said. "The timeliness of deploying the seasonal flu vaccine approach for pandemics is not the best way to go."

Vaccines, which prime the body to remember to attack incoming pathogens, also don't do the best job of protecting people who have diminished immune function, such as seniors and those with chronic health problems.

The new treatment, which is delivered through a nasal spray, gets around that problem because it doesn't require the body to mount an immune attack.

Instead, the nasal spray contains many copies of small, harmless viruses called adeno-associated viruses. The simple genome of these viruses can be altered in the lab to carry instructions for making special proteins called broadly neutralizing antibodies.

Broadly neutralizing antibodies are rare super antibodies that are capable of disarming many kinds of flu strains.

When researchers insert the instructions for making those antibodies into the genome of adeno-associated viruses, the viruses act like Trojan horses. They infect cells in the nose, inject the altered genetic material and turn the cells into factories that crank out many copies of the broadly neutralizing proteins.

"The way I envisioned it was sort of a bioshield," Wilson said. "I wanted to focus the production of the antibody to the site where flu enters our body."

In animal tests, researchers showed that mice, ferrets and monkeys made many copies of the super antibody after they inhaled the gene therapy treatment. And the protection seemed to last for a while. Experts note, however, that promising research in animals often does not pan out in humans.

"In mice, it persists up to a year," Wilson said. "In monkeys, we think we're going to see expression up to six months."

The treatment also appears to work pretty quickly. Wilson said the animals were fully protected about three days after their nasal passages were swabbed.

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