New Vaccines For A Pandemic

Using DNA, vast amounts could be made quickly. But will the drugs work?

If Dr. John Beadle, chief medical officer at British biotech startup PowderMed Ltd., is right, the U.S. and the rest of the world are making a big mistake. Sometime in the coming years a deadly strain of influenza will strike. If the bird flu that has already killed more than 60 people in Asia and is spreading to Europe mutates into a something that can jump from person to person, the result could be a global pandemic: millions of people dead. Fearing the worst, public health authorities worldwide are vying to stockpile anti-viral drugs. But there aren't enough of them to go around, and they may not work all that well, anyway.

What's needed is the ability to quickly make vast amounts of a vaccine. That's why President George W. Bush met with CEOs of the six major vaccine makers on Oct. 7 to try to prod them into boosting their capacity. But health experts agree that more production alone isn't the answer. Today's 1950s-era manufacturing method requires growing flu viruses in millions of chicken eggs, and it takes nine months or more to make a batch. Says Beadle: "The pandemic will have come and gone before we have the vaccine. That is what shocks me."

So his company and others are working on speedier, more modern alternatives. One promising route is growing the virus in vats of cells. Chiron Corp. (CHIR ) is in late-stage trials with a vaccine made from such cell-grown viruses. The method is also being developed by leading flu-vaccine maker Sanofi Pasteur Inc. (SNY ) and others, and promises to cut months off production times.


Beadle has a more radical solution -- vaccines constructed from DNA. Trials, set for next year, are needed to prove that such vaccines can actually protect people from flu. But if the approach works, it would be a major advance. "DNA has some real advantages for a pandemic vaccine," notes University of Rochester professor Dr. John Jay Treanor, who tests flu vaccines. "There is no need to handle live viruses, and there are no complicated purification steps." Instead, the vaccine is largely comprised of a few genes from the virus. Once in the body, the genes tell cells to make viral proteins, which stimulate an immune response.

Such a vaccine is "trivial" to manufacture, says Erik A. Henchal, former commander of the U.S. Army Medical Research Institute of Infectious Diseases. Different genes could be swapped in, enabling rapid production not only of vaccines against new flu strains, but also against other threats. "I'm interested in encouraging this going to trial for flu because I see it as a model for biodefense," says Henchal. Beadle figures that once the technology is proven, his company could make enough vaccine for all Americans in a kitchen-size factory in just six weeks.

Given the promise of DNA vaccines, others, such as Chiron and Merck & Co. (MRK ), have tried to make them. Typically, however, experimental versions have failed to generate a sufficient immune response. PowderMed's data look far better, researchers say. One reason is the delivery method. Tiny gold particles are coated with vaccine and shot into the skin at supersonic speeds. "They know what they are doing," says Treanor.

It sounds simple, though major hurdles remain. The next step is proving DNA vaccines work against regular flu -- and that takes money. So far, the U.S. Health & Human Services Department (HHS) has awarded $100 million to Sanofi to make a vaccine against avian flu using eggs and $97 million to develop cell-culture production facilities. HHS is about to hand out another award, but it has told PowderMed it has been dropped from consideration. Too unproven.

Cell-culture vaccines aren't proven, either, retorts Beadle: "Even if there were only a 5% chance that DNA vaccines offer the answer, wouldn't you want to put significant resources behind it to find out?" Others agree -- and Congress is making noises about intervening. "We need to learn that we can't keep doing business as usual," says Dr. Gary J. Nabel, director of the Vaccine Research Center at the National Institutes of Health. "We should have been working on these new technologies, like DNA vaccines, 10 years ago." Maybe the threat of a global pandemic will correct that mistake.

By John Carey in Washington

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