The team at Saint Louis University, led by Mark Buller, created the superbug to figure out how to defeat it, a key goal of the government's anti-terrorism plan.
The researchers designed a two-drug cocktail that promises to defeat their exceptionally deadly virus. They hope to publish their work soon in a peer review journal.
"The whole focus was to contribute to the biodefense agenda of the country," Buller said.
Buller spliced a gene known to suppress the immune system into the mousepox virus, then injected the combined strand into vaccinated mice. All of them died.
Mousepox can't be passed to humans, but it's a close relative to smallpox, making it an ideal virus to study in animals.
The research highlights a contentious discussion among scientists and security experts: Does publication of such work help or hinder the biodefense effort? Should such studies be conducted at all?
In response to heightened security concerns, many scientific journals have censored studies with national security implications. When Buller presented his results last week at an international biodefense conference, it prompted debate.
Some feared that publication of such information, regardless of whether scientists' intentions are altruistic, could help terrorists create biological weapons laced with genetically modified superbugs. Such germs are created by splicing drug-resistant genes in viruses normally defeated by vaccines.
"In the Soviet Union, there was some research trying to develop genetically engineered smallpox," said Ken Alibek, a former top scientist in the Soviet biological weapons program who came to the United States in 1992. "It wasn't very successful, but now with all the new advances in technology, know that it's pretty much obvious that it can be done."
Alibek, a director of George Mason University's National Center for Biodefense, believes Buller's work and similar research should be confidential to impede terrorists and rogue nations from acquiring knowledge about genetically engineered bioweapons.
Buller counters that publicizing such work will deter terrorists by showing that scientists can build defenses against souped-up bioweapons. Buller also believes scientists must genetically engineer pathogens to understand how to defeat them.
"All this is out there," Buller said of bioweapons research. "There are cookbooks easily attainable on how to make this stuff."
Buller said his work replicated a nearly 3-year-old Australian study, which the scientific community continues to debate.
In that study, scientists trying to beat back an overabundance of mice in Australia spliced a single foreign gene into a typically mild mousepox virus in hopes of creating a genetically engineered sterility treatment. Instead, they created a mousepox strain so powerful that it killed even those mice inoculated against the virus.
Buller's team improved upon the Australian accident, said Larry Kerr of the White House Office of Science and Technology Policy.
"They did a more thorough analysis," Kerr said. "It's more substantive and it went a step further: They developed a counter measure."
Buller said infected mice recovered when treated with a combination of anti-viral drugs, providing hope that a treatment against genetically engineered smallpox could be developed.
Smallpox historically kills about a third of its victims and can be transmitted from person to person, unlike anthrax and other biological weapons.
Smallpox has plagued humans for centuries, and it's believed to have killed more people than all wars and epidemics combined. Death typically follows massive hemorrhaging.