When reports leaked out that both Iraq and North Korea might have obtained supplies of the smallpox virus, the United States responded by spending tens of millions of dollars to stockpile smallpox vaccines. But Mark Buller, a microbiologist at Saint Louis University, warns that those vaccines could be useless if terrorists make a few genetic tweaks to the virus.
Aided by government funding, Buller and his colleagues set out to create a more lethal version of the mousepox virus. The researchers spliced a gene for interleukin-4, an immune-system chemical messenger, into the virus and then exposed a group of vaccinated mice. Infected cells immediately began producing unnaturally high quantities of the interleukin. “The interleukin-4 jammed up the signaling the immune system uses to mount its normal response,” Buller says. Unchecked, the virus multiplied freely and killed all of the mice.
Although mousepox is species-specific, Buller’s technique is not, raising the specter that researchers could engineer other superviruses, either by accident or on purpose. That possibility has prompted heated debate on whether this kind of research should be stopped. Buller argues that his research is necessary. “We’re creating a worst-case scenario,” he says. “Do I think that a super smallpox will one day be unleashed? No. Do I want to have the best understanding of what to do just in case it does? Yes.” Further experiments provided a glimmer of hope: Combining antiviral drugs with treatments that block interleukin-4 saved all of another group of mice, hinting that targeted treatments could help defeat a targeted attack.