Cold, Flu, & Cough Health Center

Designer Antibodies Fight Bird Flu

Oct. 13, 2006 -- Designer antibodies protect mice from bird flu infection -- and cure mice dying of bird flu, a Singapore/U.S. research team reports.

The new treatment uses cloned mouse antibodies -- monoclonal antibodies or mAbs -- that neutralize the H5N1 bird flu virus. The antibodies are "humanized." That is, they are genetically engineered to contain a bit of human antibody so that the human immune system does not recognize them as foreign.

Mice given several times the lethal doses of H5N1 virus die in nine days. But the same lethal dose of virus had no effect on mice that had been treated with the mouse antibodies.

And the antibodies cured mice of otherwise-lethal bird flu, even when given three days after they received a lethal dose of the virus.

"We are able to treat an ongoing H5N1 infection," study researcher Jacco Boon, PhD, tells WebMD. "One and three days after infection, it worked -- although at three days you need a higher dose of antibody. To the best of my knowledge, that is the best reported so far."

Boon is a member of the lab directed by flu expert Richard J. Webby, PhD, at St. Jude Children's Hospital, Memphis. Brendon J. Hanson, PhD, and colleagues at DSO National Laboratories, Singapore, collaborated with Webby's team for the study.

The study appears in the Oct. 13 issue of the open-access, online journal Respiratory Research.

From Mice to People?

So will it work in people? That's not known, says bird flu expert John Treanor, MD, of the University of Rochester, N.Y.

Flu infection in mice differs from flu infection in people. But there's evidence that when it comes to H5N1 bird flu, the two mammals are more alike than different.

"The treatment would be important, and it might work," Treanor tells WebMD. "I don't know if it would be practical. MAbs tend to be very expensive."

MAb-based treatments, such as the cancercancer drug Avastin, already exist. But just a month's treatment with Avastin costs thousands of dollars. There's no way such a drug could help more than a very few people if there were a worldwide bird flu pandemic.

But what if bird-flu mAbs could be used not to treat a pandemic, but to nip it in the bud? That is the plan, says Boon.

The idea would be to stockpile about 3 million doses of the bird-flu mAb. Then, as soon as the world learned of a bird flu outbreak, the treatment would be given to everyone in the surrounding area. Mathematical models suggest that such a plan might work.

How long would it take to make 3 million doses of such a cutting-edge drug?

"We would expect that the 3 million-dose level could be reached within approximately six months," Hanson tells WebMD.