Virulent smallpox stymied as a weapon.

• Position: Bioterrorism

Scientists have shown for the first time that a protein in the nucleus of victims' cells triggers progression of smallpox-related illnesses, a finding that could help prevent use of such viruses as bioterrorism weapons. The researchers have found that poxviruses move to the second and third stages of development by recruiting a protein, called TATA-binding protein, in the nucleus of mammals' cells.

"This protein is required for activation of the middle- and late-stage pox virus genes," explains Steven Broyles, professor of biochemistry at Purdue University, West Lafayette, Ind. "In the past, we were just groping around. We now have a model for how the pox virus growth process is orchestrated."

Although the last naturally occurring case of smallpox was in Somalia in 1977, experts believe that the disease and related viruses could be used as biological weapons. Though most occur naturally, it is possible that bioterrorists could engineer viruses and bacteria to increase their virulence substantially, make them resistant to currently used vaccines and drugs, or partner two biological agents to create a new, more lethal illness, according to the Centers for Disease Control and Prevention, Atlanta.

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