Microbiology and Immunology

WORLD OF MICROBIOLOGY AND IMMUNOLOGY Bioterrorism

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greatly based on recent developments in molecular biology,

especially those in genetic engineering. Organisms from bac-

teriato cows are being genetically modified to produce phar-

maceuticals and foods. Also, new methods of disease gene

isolation, analysis, and detection, as well as gene therapy,

promise to revolutionize medicine.

In theory, the steps involved in genetic engineering are

relatively simple. First, scientists decide the changes to be

made in a specific DNA molecule. It is desirable in some

cases to alter a human DNA molecule to correct errors that

result in a disease such as diabetes. In other cases, researchers

might add instructions to a DNA molecule that it does not

normally carry: instructions for the manufacture of a chemi-

cal such as insulin, for example, in the DNA of bacteria that

normally lack the ability to make insulin. Scientists also mod-

ify existing DNA to correct errors or add new information.

Such methods are now well developed. Finally, scientists

look for a way to put the recombinant DNA molecule into the

organisms in which it is to function. Once inside the organ-

ism, the new DNA molecule give correct instructions to cells

in humans to correct genetic disorders, in bacteria (resulting

in the production of new chemicals), or in other types of cells

for other purposes.

Genetic engineering has resulted in a number of impres-

sive accomplishments. Dozens of products that were once

available only from natural sources and in limited amounts are

now manufactured in abundance by genetically engineered

microorganisms at relatively low cost. Insulin, human growth

hormone, tissue plasminogen activator, and alpha interferon

are examples. In addition, the first trials with the alteration of

human DNA to cure a genetic disorder began in 1991.

Molecular geneticists use molecular cloningtechniques

on a daily basis to replicate various genetic materials such as

gene segments and cells. The process of molecular cloning

involves isolating a DNA sequence of interest and obtaining

multiple copies of it in an organism that is capable of growth

over extended periods. Large quantities of the DNA molecule

can then be isolated in pure form for detailed molecular analy-

sis. The ability to generate virtually endless copies (clones) of

a particular sequence is the basis of recombinant DNA tech-

nology and its application to human and medical genetics.

A technique called positional cloning is used to map the

location of a human disease gene. Positional cloning is a rela-

tively new approach to finding genes. A particular DNA

marker is linked to the disease if, in general, family members

with certain nucleotides at the marker always have the disease,

and family members with other nucleotides at the marker do

not have the disease. Once a suspected linkage result is con-

firmed, researchers can then test other markers known to map

close to the one found, in an attempt to move closer and closer

to the disease gene of interest. The gene can then be cloned if

the DNA sequence has the characteristics of a gene and it can

be shown that particular mutationsin the gene confer disease.

Embryo cloning is another example of genetic engineer-

ing. Agricultural scientists are experimenting with embryo

cloning processes with animal embryos to improve upon and

increase the production of livestock. The first successful

attempt at producing live animals by embryo cloning was

reported by a research group in Scotland on March 6, 1997.

Although genetic engineering is a very important com-

ponent of biotechnology, it is not alone. Biotechnology has

been used by humans for thousands of years. Some of the old-

est manufacturing processes known to humankind make use of

biotechnology. Beer, wine, and bread making, for example, all

occur because of the process of fermentation. As early as the

seventeenth century, bacteria were used to remove copper

from its ores. Around 1910, scientists found that bacteria

could be used to decompose organic matter in sewage. A

method that uses microorganisms to produce glycerol synthet-

ically proved very important in the World War I since glycerol

is essential to the manufacture of explosives.

See alsoFermentation; Immune complex test; Immunoelec-

trophoresis; Immunofluorescence; Immunogenetics; Immu-

nologic therapies; Immunological analysis techniques;

Immunosuppressant drugs; In vitroand in vivoresearch

BBioterrorismIOTERRORISM

Bioterrorism is the use of a biological weapon against a civil-

ian population. As with any form of terrorism, its purposes

include the undermining of morale, creating chaos, or achiev-

ing political goals. Biological weapons use microorganisms

and toxins to produce disease and death in humans, livestock,

and crops.

Biological, chemical, and nuclear weapons can all be

used to achieve similar destructive goals, but unlike chemical

and nuclear technologies that are expensive to create, biologi-

cal weapons are relatively inexpensive. They are easy to trans-

port and resist detection by standard security systems. In

general, chemical weapons act acutely, causing illness in min-

utes to hours at the scene of release. For example, the release

of sarin gas by the religious sect Aum Shinrikyo in the Tokyo

subway in 1995 killed 12 and hospitalized 5,000 people. In

contrast, the damage from biological weapons may not

become evident until weeks after an attack. If the pathogenic

(disease-causing) agent is transmissible, a bioterrorist attack

could eventually kill thousands over a much larger area than

the initial area of attack.

Bioterrorism can also be enigmatic, destructive, and

costly even when targeted at a relatively few number of indi-

viduals. Starting in September 2001, bioterrorist attacks with

anthrax-causing bacteriadistributed through the mail targeted

only a few U.S. government leaders, media representatives,

and seemingly random private citizens. As of June 2002,

these attacks remain unsolved. Regardless, in addition to the

tragic deaths of five people, the terrorist attacks cost the

United States millions of dollars and caused widespread con-

cern. These attacks also exemplified the fact that bioterrorism

can strike at the political and economic infrastructure of a tar-

geted country.

Although the deliberate production and stockpiling of

biological weapons is prohibited by the 1972 Biological

Weapons Convention(BWC)—the United States stopped for-

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