Biological Weapons, Genetic Identification

Biological Weapons, Genetic Identification

Biological weapons are weapons whose payload consists of microorganisms that can cause infections, or the toxic components of the microorganisms. Examples of microorganisms include viruses (e.g., smallpox, Ebola, influenza), bacteria (e.g., Bacillus anthracis, Clostridium botulinum, Yersinia pestis ) and protozoa. The most prominent example of a toxic component is the variety of toxins produced and released from bacteria (e.g. neurotoxins produced by Clostridium ).

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, protozoal, and other microbial sequences in databases, in order to determine if the deduced sequence resembles a catalogued sequence. In this way, the nature and identity of biological weapons can be determined.

Genetic engineering has also made possible the splicing of the genetic determinants for a lethal agent from one microorganism or other life form into another microbe. For example, the former Soviet Union experimented with the instillation of the gene responsible for the production of cobra toxin into normally harmless bacteria that reside in the intestinal tract.

While recent events in the United States and in other countries, in particular Iraq, have brought biological weapons into prominence, the military use of biological weapons is centuries old. The bloated bodies of disease victims were routinely dumped into wells to poison the drinking water, or were even catapulted over the walls of fortified cities that were under siege.

More recently, biological warfare was an accepted part of the military campaigns of governments around the world. During World War I, for example, Germany actively explored the weaponization of Bacillus anthracis and Burkholderia mallei. The latter causes Glanders disease in cattle. Its' use was intended to cripple the agriculture base of the enemy.

During World War II, Britain also intended to cripple German agriculture by airdropping discs (or cakes) of anthrax. Indeed, five million anthrax cakes were ultimately produced, although they were not used. Also during this war, German and Japanese prisoners were used as guinea pigs in the testing of microbial weapons, including hepatitis A, Plasmodia species, Rickettsia, Neisseria meningitis, Bacillus anthracis, Shigella species, and Yersinia pestis. The U.S. had an active biological weapons program during World War II, and extending even into the 1960s. This program was finally terminated in 1968 by the order of then president Richard Nixon.

The production of biological weapons can be accomplished with relatively unsophisticated microbiological technology and by a typically trained microbiologist. Furthermore, the equipment necessary to accomplish weaponization (i.e., incubators, autoclaves, fermenters, centrifuges, refrigerators, and lyophilizers) can be housed in only a few thousand square feet. Thus, biological weapons manufacture is not difficult to conceal.

Furthermore, while biological weapons can be deployed in traditional weaponry (i.e., rockets), the weapons can also be literally carried in someone's pocket to the target site. This can make the deployment of biological weapons virtually impossible to stop, unless the carrier passes near an instrument designed to detect the biological agent.

Microorganisms are very light and so can be dispersed easily in air currents. This is especially true for bacterial spores, which, when dried, are powdery in texture. Furthermore, because exposure to only a few spores can be sufficient to cause disease (e.g., the inhalation form of anthrax, which is caused by spores of Bacillus anthracis ), the biological weapon can be easily delivered to the target. The anthrax-containing letters that were mailed in the United States in the latter part of 2001 attest to the ease of delivery.

Bacillus anthracis and Clostridium botulinum are two prominent examples of spore-forming bacteria that have been used as bioweapons. Spore forming bacteria normally grow and reproduce as "vegetative" cells. But, in harsh environmental conditions that threaten the survival of the bacteria, the microbes have evolved the ability to transform into an almost dormant form known as a spore. The spore is surrounded by a resilient coat that allows it to persist for decades, perhaps even centuries. When conditions again become favorable for growth and reproduction, the spore resuscitates into the vegetative form. Thus, if spore biological weapons do not kill immediately, the residual spores can persist to cause illness many years later.

The microbial agents used as biological weapons are typically highly infectious. The direct exposure of even a small number of people to the weapon can quickly lead to a large number of illnesses or casualties. Bacteria such as Clostridium botulinum and various species of Salmonella readily cause contamination, either by their growth in food or by the production of potent toxins. Such food-borne microbial threats are also considered to be biological weapons. Indeed, in the aftermath of the U.S. anthrax attacks in 2001, the vulnerability to sabotage of the food production and supply systems in many countries has become evident.

Ironically, the features that make biological weapons attractive to those who wage war or terrorism, namely their ease of dispersal, particularly via air, and their infectivity, has also proved to be a stumbling block to their use. A shift in the prevailing wind can carry the lethal payload back to those who deployed it, similar to the chemical warfare casualties that occurred during World War I. For example, the open air testing of anthrax on Gruinard Island off of the coast of Scotland in 1941 made the island inhabitable for decades afterwards. In a second example, as part of the U.S. Army's "Operation Sea Spray" in 1951–1952, balloons filled with Serratia marcescens were exploded over San Francisco, to evaluate the effectiveness of aerial biological warfare on a major urban center. The organism, which up until then was thought to be innocuous, allegedly produced an increase of pneumonias and urinary tract infections in the citizens of the city. As a final example, an accidental release of anthrax spores from a bioweapons facility in 1979 killed 66 people and sickened over 70 who were 4 kilometers downwind, in the city of Sverdlovsk, in the former Soviet Union. Sheep and cattle up to 50 kilometers downwind became ill.

█ FURTHER READING:

BOOKS:

Cirincione, Joseph, Jon B. Wolfsthal, Miriam Rajkuman, and Jessica T. Mathews. Deadly Arsenals: Tracking Weapons of Mass Destruction. Washington, D.C.: Carnegie Endowment for International Peace, 2002.

Hamzah, Khidr Ald Al-Abbis, and Jeff Stein. Saddam's Bombmaker: The Terrifying Inside Story of the Iraq Nuclear and Biological Weapons Agenda. New York: Scribner, 2002.

Lavoy, Peter R., Scott D. Sagan, and James J. Wirtz. Planning the Unthinkable: How New Powers Will Use Nuclear, Biological, and Chemical Weapons. Cornell University Press, 2001.

SEE ALSO

Anthrax Weaponization
Biocontainment Laboratories
DNA
Infectious Disease, Threats to Security
Pathogens