Biological Weapons, Genetic Identification

The ability to use microorganisms and their components as weapons has been a reality for decades. Individual countries and organizations such as the United Nations have mounted efforts to detect the use and presence of microbial weapons. A recent example is the effort by United Nations and United States inspectors to detect evidence of microbial weapons in Iraq in the aftermath of the two Gulf Wars.

Initiatives like the aforementioned represent the use of forensic science. Traditional forensic investigations relied on the use of techniques that required the growth of the target microorganism. This approach has limitations. For example, the growth conditions selected might not be suitable to permit the growth of the target microbe. Furthermore, the laboratory facilities required, especially for the culture of highly infectious organisms, may not be widely available.

The use of genetic techniques of identification represents a promising forensic approach. Genetic technologies can be useful in the detection of biological weapons. Of particular note is the polymerase chain reaction, or PCR, which uses select enzymes to make copies of genetic material. Within a working day, a target sequence of genetic material can be amplified to numbers that are detectable by laboratory tests such as gel electrophoresis. If the target sequence of nucleotides is unique to the microorganism (e.g., a gene encoding a toxin), then PCR can be used to detect a specific microorganism from among the other organisms present in the sample.

Hand-held PCR detectors that have been used by United Nations inspectors in Iraq during their weapons inspections efforts of 2002–2003 purportedly can detect a single living Bacillus anthracis bacterium (the agent of anthrax) in an average kitchen-sized room.

The sequence of components that comprise the genetic material (genome) of a microorganism can also be deduced using techniques such as electrophoresis. Once a sequence is known, it can be compared to the many bacterial, viral, protozoan, and other microbial sequences in databases in order to determine if the deduced sequence resembles a catalogued sequence.