The biotech trade journal Acumen (current issue Vol. I, No. IV) has a must-read on bioterrorism, including details on the extent of the work done by the Soviet biowarfare center Biopreparat. Amongst the most chilling creations were "binary inocularies," genetically-modified diseases containing two different viruses, one of which was coded to express itself only when the first virus was treated.

For example, the Soviets considered a genetic crossbreed of plague with Venezuelan equine encephalitis, in which plague manifested itself first. Upon treatment with tetracycline, the VEE virus would be activated, attacking an already weakened host (VEE has a mortality rate of ~20% for those who develop encephalitis). With literally tens of thousands of skilled bioweapons creators out of work in the former Soviet Union and beyond, the threat of a bioweapons black market is very real indeed.

For those who don't have access to the journal, GMU has the primary article from the issue online.