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High-Velocity Vaccines


There was a time when getting investors interested in a startup whose lead product was a DNA flu vaccine was a tough sell. Not only were investors skeptical of DNA vaccines, which despite working well in animals never proved effective in humans, but "flu vaccines weren't seen as a sexy or lucrative business," says Dr. John Beadle, a founder of Oxford (Britain)-based PowderMed Ltd. and its chief scientific officer.

No longer. With preparations for protecting humans against an avian flu outbreak taking on ever-increasing urgency, PowderMed is suddenly in the spotlight. The company claims it will be able to engineer a vaccine for a potential pandemic flu in less than three months, roughly half the time it would take traditional vaccine makers to respond to any outbreak. While others are also scrambling to develop DNA vaccines, experts are giving PowderMed the early edge. Says Dr. John Jay Treanor, professor of medicine and infectious diseases at the University of Rochester: "The guys at PowderMed really know what they are doing."

A DNA flu vaccine would have huge advantages over traditional ones. Conventional flu vaccines work by eliciting an immune response from an inactivated or weakened version of the virus. DNA vaccines use genes from the flu virus itself. Once introduced in the body, these genes instruct cells to make viral proteins, which stimulate an immune response. The key difference between DNA and regular vaccines is that the traditional methods require growing the live virus in chicken eggs, a process that takes six to nine months. Huge amounts of DNA vaccine, by contrast, can be made in just a few months by extracting viral DNA from cultures.

Equally promising as the drug itself could be PowderMed's needle-free technology to deliver the vaccine. If all goes as planned, doctors could pump a tiny but highly targeted amount of PowderMed's vaccine directly into specific cells with a high-powered "gene gun." Although gene-gun technology has already been used successfully in bioengineered crops, PowderMed owns the rights to develop the technology for use in humans.

What makes PowderMed's gene gun so special is its ability to fire microscopic amounts of DNA-coated gold particles into the skin at supersonic speed. Past efforts to make DNA vaccines work involved using needles to inject DNA directly into the muscle. That technique works well in small animals but poorly in humans. PowderMed's technology enables it to "get the DNA right into the immune cells of the skin," explains CEO Clive Dix.

That capability would have huge implications in the event of a flu pandemic. Current methods of production would only yield enough vaccine for 75 million people -- a tiny fraction of the world's population of 6 billion, says Peter Dunhill, chairman of the Advanced Centre for Biochemical Engineering at University College London. PowderMed's approach promises, in theory, that many more people could receive the vaccine -- and get it more quickly. Just over one kilogram of DNA vaccine, for instance, would be enough to inoculate the entire U.S. population with a prime and a booster shot, according to PowderMed.

It all sounds extremely promising, but PowderMed has a long way to go. First, the company must prove in upcoming large-scale clinical trials that its vaccine can protect people from flu generally. At the same time, it will begin clinical testing of its DNA vaccine for the H5N1 strain of avian flu early next year. But even if those trials succeed, it would be at least four to five years before any new DNA flu vaccine hits the market. Another challenge: ramping up production of the disposable plastic gene guns. Although the company was eliminated from the current round of possible U.S. government grants, PowderMed is in discussions with governments in Britain and Southeast Asia about funding for a large-scale manufacturing facility in the event of a pandemic.

PowderMed has enough money to get through 2006, by which time it expects to have the data necessary to persuade health authorities in the U.S., Europe, and the rest of the world that its technology is effective. Until then, PowderMed's Beadle concedes, it will remain "a relatively small company trying to save the world on a relatively small budget."

By Kerry Capell, with John Carey in Washington, D.C., and Maha Aziz in London


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