Quotes of the Day

Imagine this scenario: terrorists release an airborne, antibiotic-resistant strain of anthrax in a major European capital. Without vaccines or antitoxins to reduce fatalities, the public is largely unprotected. But the government quickly dispenses a new nasal spray that puts people's immune systems into overdrive, protecting them not only against anthrax but a whole range of pathogens, including many of the deadly bioterrorist agents that governments believe are most likely to be used.

It sounds farfetched, but last week's ricin arrests in London show that the possibility of a bioterror attack is not fantasy. British Prime Minister Tony Blair said that such an attack was "present and real and with us now." All the more reason to develop effective vaccines and antidotes — fast.

The U.S. Defense Advanced Research Projects Agency (DARPA) and Britain's Defence Science and Technology Laboratory at Porton Down are doing just that. They say that a protective nasal spray like the one described above could be a few years away. Coley Pharmaceutical Group, a U.S. firm working with both military agencies, says preclinical data show that its CpG drug protects mice against anthrax, certain strains of smallpox, the Ebola virus and other potential bioterror agents. Normally the body's immune cells detect pathogens, triggering protective measures after an infection takes hold. CpG mimics immune cells, causing the body to think it is infected before it actually is. The body's immune system is then at full strength when an infection is introduced. "CpG is potentially a very powerful addition to our arsenal," says Rick Titball, group leader for microbiology at Porton Down military labs. The CpG research has now become part of the U.S. Department of Defense's effort to develop "one drug for all bugs," says John Carney, pharmalogics program manager at DARPA.

But there are enormous hurdles yet to clear. Scientists must still prove that CpG will provide humans with the same protection it affords mice, and that the drug is an improvement on existing vaccines. Jean-Paul Levy, head of Medical and Public Health at the Pasteur Institute in Paris, is skeptical. Levy doubts CpG's ability to work alone as a magic bullet against a range of pathogens. Because CpG introduces a nonspecific stimulation of the immune system, Levy feels it has little chance to offer adequate protection. "CpG could end up being as efficient as lighting candles in church," he says. According to Titball, one drawback to the CpG nose spray is that the protective effect starts to wear off after two weeks, so vaccines are still considered the most important defense against bioterrorism.

So darpa and Porton Down are also applying Coley's CpG to improve the anthrax vaccine currently used to innoculate U.S. troops. That drug requires six doses and 18 months to produce immunity. But Coley's CpG, used together with vaccines, could reduce the number of doses, induce immunity more quickly and prolong protection.

The Pasteur Institute is working on its own approach to improving anthrax vaccines. The new French treatment could provide better protection because in addition to neutralizing toxins, it can stop bacteria from multiplying at the early stages of disease, according to Michèle Mock, team leader on the Institute's anthrax vaccine project. The current anthrax vaccine only neutralizes toxins. The same is true for a vaccine against tularemia, or rabbit fever, a bacterium that can cause fatal illness. With funding from the U.S. government, the University of Umeå in Sweden is trying to identify protective components of the tularemia bacterium and use them to develop a vaccine. And in Germany, scientists are developing a vaccine against botulism toxin. None of them will be ready anytime soon — so for now, there are plenty of bioterror scenarios without happy endings.

• JENNIFER L. SCHENKER/Paris
• The race to develop a new generation of vaccines