Biodefense: Guest column // David Cullen, Ph.D.With biological warfare, real-time detection is key

Increased attention to the threat posed by weapons of mass destruction can be traced to the first Gulf War. At that time, the Department of Defense became acutely concerned about the potential for use of chemical and biological warfare agents against troops deploying to the Gulf Region. This situation gave rise to a renewed interest — from policy makers to technology developers — in developing truly effective countermeasures against these agents.

Fast-forward to the discovery of bacillus anthracis (anthrax), in letters traveling through the U.S. mail system a few weeks after the 11 September 2001 attacks. This event solidified defense against Weapons of Mass Destruction as no longer just a Defense Department problem but also a problem for the civilian world. Other types of WMD require attention, but it is biological warfare agents (BWA) that cause the most concern. This is, in large part, because very small quantities of these agents can produce huge effects, making it the ultimate asymmetric weapon. So, what progress has been made in the two decades that have passed since the first Gulf War?

There is a full system of countermeasures required completely to address BW agents (including medical countermeasures and public health response), but I will focus on the problem of initial detection and the identification of these agents. What system characteristics are desired? First, the highest premium is placed on the accuracy of detection. Any detection/identification system needs accurately to identify the agent with a very high level of sensitivity and with an almost non-existent false positive rate. This represents a near-perfect sensor (especially since the sensitivity and false positive characteristics are inversely proportional).

The system must also have tremendous breadth due to the vast number of agents that might be encountered, and it must provide answers in as fast a time as possible. Since the most efficient mechanism of BW exposure is through aerosol inhalation, most recent developmental efforts have been focused on aerosol detection systems.

The system needs to be affordable, however, affordability is in the eye of the beholder. The reality is that the only current technologies capable of really identifying BW agents in samples are laboratory devices that in some cases have been adapted for the field. Technologies such as Polymerase Chain Reaction (PCR) devices provide exquisite sensitivity and false positive characteristics, but they are slow and they are expensive. They provide, however,