With biological warfare, real-time detection is key

the most important capability to any BW detection system: They get the right answer. That said, it is cost prohibitive to run them continually so they are typically used to analyze samples that have been collective over a period of time (batch sampling), or they are coupled in a system with much lower fidelity triggering devices which basically cue them as to when an analysis needs to occur. Since it is not affordable at this time to use the high fidelity system in a continuous mode, users have created tiered systems which, when taken in aggregate, provide the necessary capabilities.

This tiered system typically comprises fast, sensitive detecting sensors, aerosol collectors, and identification components (sometimes different ones with different levels of fidelity). The first components mentioned generally detect non-specifically so their purpose is to initiate other actions, starting with sample collection. Since the main threat considered here is an aerosol threat, a method for getting biological particles out of the air must be created. There are many different types of technologies that perform this role, from small, low-flow systems to larger, high-flow systems. The choice is usually based on availability or line power, or the requirement to use batteries. Samples are usually collected into some type of aqueous solution buffered to provide preservation of biological samples.

The final step in this process is to perform tests on the collected aerosol samples. These tests range from the already mentioned PCR or nucleic acid detecting technologies (these are the most sensitive and specific), to antibody-type tests that are not as sensitive and specific but are more robust and easier to perform. By limiting the number of high-fidelity tests that the system performs, cost is controlled since the other portions of the system (detecting and sample collection) are relatively cheap to perform.

Based on the current state of play, what should be done to improve this concept?

The panacea is to develop a real-time sensor with the kinds of sensitivity and specificity that PCR experiments can provide. This, however, is a long way off. In the interim it makes sense to optimize the various components of the system described in our goal.

The overall system’s cost is strongly driven by the number of high-fidelity analyses that it is required to perform. It follows that a natural place to improve the system will be on the detector side. We need to strive to make devices that are more sensitive and more specific. Today’s triggers are typically optical-spectroscopy based. The most widely employed use ultra violet excitation light of a frequency where biological materials absorb. The sensors then detect the fluorescence that results. Any steps that could be taken to improve the specificity of these measurements would obviously improve the overall system. New spectroscopies are being investigated all the time and there are some very encouraging results which probably only require maturation. There is probably not a tremendous amount of improving that needs to be done to the core, air-sampling technologies. For field deployment, however, it is always a good thing if more sampling power can be gotten in a smaller package and for a lower power cost.

It is probable that the largest improvements in any identification system’s performance will come in the form of smaller packages, more automated measurement, and faster measurement. Considerable efforts are being put toward accomplishing these types of improvements. In addition, it is possible to reduce the costs of these systems by more carefully managing reagent consumables and sample sizes. Clearly, progress is being made in making evolutionary improvements to each of these system components, and this will result in more responsive systems that are affordable.

David Cullen, Ph.D., is Senior Vice President for Technology Transition, ICx Technologies