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Carol Berkower
[email protected]
410-908-2535
July 6, 2013
Word count: 1,446
[With inset: 1,937]
Note: This article was published in an international children's science magazine in
2013. The printed version is in Chinese.
The Secret World of Biological Warfare
Biological weapons - a short history
Think about weapons, and what comes to mind? Weapons exist in many forms:
guns and swords, bows and arrows, missiles and tanks, drones and corpses. That's
right, corpses. In 1346, the Mongol army made weapons from corpses. The Mongols
had laid siege to a city named Caffa in what is now the Ukraine, but the residents of
Caffa, whose city was protected by a strong wall, refused to surrender. When the
bubonic plague, a deadly disease, started to spread among Mongol soldiers, their
chief ordered his army to catapult the corpses of dead soldiers over the city walls.
Plague broke out within the walls of Caffa and many residents fled. Wherever
plague-ridden Caffans went they spread disease, contributing to a massive epidemic
of bubonic plague known as the Black Death that killed millions throughout Europe.
Those 14th-century Mongols were engaging in an early form of biological warfare,
which is defined as the deliberate use of living things or their toxins (poisons made
by living things) as weapons. The medieval Mongols weren't the first to use
biological weapons; over two thousand years ago, warriors would toss dead animals
into wells to contaminate the drinking water of their enemies. In the wars between
American colonists and Native American Indians in the mid-1700's, an American
general plotted to spread smallpox among the Indians by giving them contaminated
blankets. (Although many Indians died from smallpox, we have no way of knowing
whether any caught it from the blankets.)
Unlike the medieval Mongols and early Americans, who didn't know what made
their corpses and blankets so dangerous, we now know that infectious diseases are
caused by microorganisms, or microbes, that are too small to be seen by the naked
eye. As a result, modern biological weapons are far more sophisticated than corpses
and blankets. These days, infectious microbes - bacteria and viruses - can be grown
in laboratories, and amounts large enough to infect many people can be packaged
into small containers. Take bubonic plague, for example. Plague is normally
transmitted from rodents to people by fleas, but what makes you sick is a deadly
bacterium that hitchhikes on the flea. Plague bacteria can be grown in test tubes in
a laboratory, and just a tiny amount, invisible to the eye, can be a deadly weapon.
In the early part of the 20th century, several countries, including Japan, the United
Kingdom, and the Soviet Union, developed biological weapons. In 1975, these
countries, along with 19 others, ratified an international treaty called the Biological
Weapons Convention, abbreviated BWC, which outlawed the development of
biological weapons. The United States destroyed its entire arsenal of biological
weapons in 1972. Researchers still study dangerous microbes, but their goal is to
learn ways to defend against a biological threat.
Anthrax, agent of modern bioterrorism
One of the most feared biological weapons is the bacterium that causes anthrax.
Anthrax bacteria form tough particles called spores that can survive for decades as a
dry powder. If a person inhales anthrax spores, they enter the lungs and start to
grow or germinate, like a dry seed that sends up a shoot when it's planted in soil and
given water. When anthrax starts growing in the lungs, it produces lots of bacteria
that can spread throughout the body. These bacteria make toxins, deadly chemicals
that destroy cells all over the body, causing severe bleeding and death.
After the 1972 treaty that made it illegal to develop biological weapons, the Soviet
Union built secret factories and grew large amounts of anthrax bacteria. In 1979,
anthrax spores were accidentally released into the air from a secret factory in the
town of Sverdlovsk. At least 66 people downwind of the factory died as a result of
inhaling these spores and many more fell ill, demonstrating the lethality of airborne
anthrax and its potential effectiveness as a deadly weapon.
In October of 2001, a single person mailed letters containing anthrax spores to the
offices of two United States senators and several news organizations, causing 22
people to get sick and five to die. Thirty thousand people who might have been
exposed to anthrax had to take antibiotics, and dozens of buildings had to be
decontaminated. Only a handful of people died in the 2001 anthrax attacks, but it
caused a huge amount of fear and disruption, which is to say, terror.
Dr. Gigi Gronvall, a senior associate at the UPMC Center for Health Security, studies
the threats posed by dangerous organisms. Dr. Gronvall believes that the growing
threat is not from countries, as it was back in the 1970's when the Biological
Warfare Convention was signed, but from terrorist groups or individuals like the
anthrax attacker. With a little bit of training, anyone can learn to grow bacteria, and
all the equipment needed to build a small laboratory can be purchased off the
internet. This could make it easier than ever for an individual or small group to
grow dangerous organisms and produce a biological weapon.
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According to Dr. Gronvall, "What happened in October of 2001 was the result of one
person…one person managed to create all kinds of havoc, and that was not the way
people thought about biological weapons when they signed the BWC."
The response to bioterrorism - send in the scientists!
Dr. Michael Kurilla directs the office of Biodefense, Research Resources, and
Translational Research at the U.S. National Institute of Allergy and Infectious
Diseases (NIAID), where he is in charge of developing new drugs and vaccines.
Although anthrax can be treated with drugs, Dr. Kurilla imagines a day when that
may not be possible. Governments stockpile large amounts of antibiotics against
anthrax, but Dr. Kurilla worries that if a terrorist obtains bacteria that are resistant
to the antibiotics, "it means that you basically have nothing." So Dr. Kurilla is
helping to develop new antibiotics that could treat drug-resistant anthrax or other
microbes.
The fact is, new dangerous microbes emerge all the time in nature. Most of these
microbes will never be used as weapons. Indeed, we are far more likely to
encounter dangerous microbes naturally, for instance by shaking hands with
someone who has the flu, than in a biological terror attack. Therefore, scientists are
using their knowledge of biological weapons to protect against natural disease
outbreaks. For example, a laboratory at NIAID is developing a vaccine for Ebola
virus, and Dr. Kurilla is helping drug companies design vaccines for a deadly strain
of flu virus that first appeared this year in China.
In this way, scientists are turning the fear of biological weapons into a positive force
that can drive medical discoveries, and some of these discoveries may completely
change the way infectious disease is treated.
Dr. Kurilla is most excited about a whole new type of antiviral drug that he is
helping to develop, which may solve an age-old problem of drug therapy. Until now,
says Dr. Kurilla, "there are drugs for HIV, there are drugs for hepatitis, there are
drugs for flu, and the drugs for flu don't work on HIV or hepatitis," and a new drug
has to be designed for every new virus that comes along. It can take years to
develop an effective drug - and for some viruses, no drug exists.
Now Dr. Kurilla is helping to develop a new kind of drug that doesn't attack the virus
directly, but instead works by helping the human body respond better to infection.
This new type of drug will be able to treat many different kinds of viral infections,
even for viruses that haven't yet been discovered. Dr. Kurilla believes that this
research "is going to open up a whole new way of treating infectious diseases."
Attacks with biological weapons like anthrax are extremely rare, but Dr. Gronvall
reasons that "even if there was never a biological weapon attack, there's a lot of
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good stuff that will come out of this research and learning about how the body fights
disease."
Hopefully, bioterror will remain a distant threat that never touches our lives. But as
long as new microbes keep emerging in nature - and they will - research will be
necessary. Scientists will continue to develop new vaccines, which prepare the body
to fight off dangerous bacteria or viruses before an infection occurs; antiviral drugs,
which fight diseases caused by viruses; and antibiotics, which treat bacterial
diseases like anthrax. Because unless we keep developing new treatments for
infectious disease, we could end up like the citizens of Caffa and the millions in
Europe and Asia who suffered one plague epidemic after another and for whom,
lacking antibiotics or any understanding of microbiology, survival was simply a
matter of luck.
##
[Inset]
Inside a biodefense research laboratory
Dr. Nancy Sullivan is head of the Biodefense Research Section in the Vaccine
Research Center at the U.S National Institute for Allergy and Infectious Disease
(NIAID) at the National Institutes of Health (NIH) in Bethesda, Maryland. Dr.
Sullivan studies viruses that cause hemorrhagic fever, a deadly condition that makes
blood vessels break down so the entire body seems to bleed from the inside. Most
people who contract hemorrhagic fever die as a result. The viruses that cause
hemorrhagic fever - Ebola, Marburg, and Lassa - are so dangerous that scientists
who handle live virus have to work in special buildings, wear protective suits that
cover their entire bodies, and breathe air that is pumped in from outside. (Dr.
Sullivan's group does not work with the live virus; only a few places in the United
States are equipped for that level of hazardous work.)
Because hemorrhagic fever is so deadly and no cure exists, these viruses are
considered high-priority, or Category A, threat agents. Dr. Sullivan is researching
ways to defend against them.
One defense against deadly microbes is a vaccine. Just like the vaccines we get as
children - for chicken pox, measles, and other viruses - an Ebola vaccine would have
to resemble Ebola virus enough to make the body think it saw the real thing, but not
enough to cause disease.
Daphne Stanley, who is in charge of the preclinical vaccine program in Dr. Sullivan's
lab, describes the lab's strategy in designing a vaccine for Ebola. "We use only a
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portion of the protein from the virus. Even though you haven't actually seen the
dangerous virus, if you were exposed to it [after being vaccinated with the protein],
your body says 'I've seen this thing before, I know to attack it,'" and the body's
immune system would quickly eliminate the dangerous virus before it could cause
disease.
When Dr. Sullivan's research group started looking for a way to protect humans
from Ebola, they designed many different vaccines. These were tested in mice, by
first injecting mice with the vaccine and then injecting them with a mouse version of
Ebola virus. If the mice survived, then the vaccine was tested in monkeys. Ebola
virus is normally fatal in monkeys, but one vaccine protected all the monkeys that
received it, a stunning result that showed for the first time that primates could be
protected from Ebola virus and suggested that it might be possible to protect
humans as well as monkeys.
Now Dr. Sullivan's vaccines are being tested in humans. Of course, you can't
vaccinate humans and then inject them with deadly virus to see if they die. But
there are other ways to tell if a vaccine is likely to protect against disease, by looking
at the antibodies and cells that appear in a person's blood following vaccination.
This work is being done with human volunteers on another part of the NIH campus.
##
Image captions and credits
Sources for images:
Images 1-4 and 9 are from the CDC Public Health Image Library, and are in the
public domain and free of copyright restrictions.
Images 5-8 are all photos taken for this story.
Image captions:
(1) Spores of the anthrax bacterium, Bacillus anthracis. Credit: CDC/Laura Rose.
(2) Vegetative (growing) form of the anthrax bacterium, Bacillus anthracis.
Credit: CDC.
(3) A squirrel is examined for fleas, which could carry plague bacteria. Credit:
CDC.
(4) White-throated woodrats, which live in the southwestern United States, may
harbor fleas that carry plague bacteria. Credit: CDC.
(5) A researcher at the NIAID studies a vaccine for Ebola virus. Credit: Carol
Berkower. [If you use the inset, I would change the caption to "Daphne
Stanley is trying to develop a vaccine for Ebola virus at the NIAID."]
(6) The Vaccine Research Center at NIAID. Credit: Carol Berkower.
(7) Dr. Gigi Gronvall at the UPMC Center for Health Security in Baltimore,
Maryland. Credit: Carol Berkower.
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(8) Dr. Gigi Gronvall at the UPMC Center for Health Security in Baltimore,
Maryland. Credit: Carol Berkower.
(9) [This is a new image to accompany the inset.] A microbiologist works in a
Biosafety Level 4 laboratory, which is designed for studying the most
dangerous microbes, such as Ebola virus. Credit: CDC/Dr. Scott Smith.
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