cover story
BY CYNTHIA ADAMS
A
PHOTOS BY NANCY EVELYN
smallpox plague is not a West
Wing television plot invention,
although it was once used as
one in a doomsday scenario. The once-rampant smallpox is believed to hold no future threat—yet it formerly brought fiefdoms and kingdoms down. Scarring and disfiguring, smallpox can blind. Worse yet, it just as often wields an exquisitely painful death. The vaccine that famously eradicated smallpox is made using an attenuated vaccinia virus. Closely related to cowpox, vaccinia has uncertain origins. Smallpox is caused by Variola major or Variola minor . Once smallpox was believed eradicated, only the United States, Britain and the Soviet Union retained research quantities of live virus in guarded laboratories. (Britain destroyed theirs after a devastating accident that led to the death of a medical photographer.) Now a number of researchers are pondering a different sort of smallpox plague—one deliberately introduced and unleashed. Valerie Cadet, a fourth year UGA doctoral student, would love to be a modern day Edward Jenner and stop it in its tracks. Cadet is a student in the department of Infectious Diseases, which is within the College of Veterinary Medicine.
What might happen if smallpox were used as a bioterrorist weapon? With the predominance of air travel, the pox could spread from continent to continent in less than 48 hours. “The continual outbreaks of monkeypox and its transference to other countries are worth noting,” says Cadet. It’s the reason she studies poxviruses. “All countries agree, however, that even a single case of smallpox anywhere in the world would be an international health emergency. In this event, all nations would respond to contain and prevent spread of the infection,” reports Public Health of Canada’s Web site. A “Soccer Mom” Working to Stop a Once and Future Plague In a UGA biosafety level-two laboratory, Cadet, a researcher and commuting mom, spends long hours with her eyes trained upon a lens. Beneath the lens is the vaccinia virus. Vaccinia, a poxvirus, is brick-shaped and contains DNA. Cadet is working to combat the smallpox virus if such a possibility—an outbreak striking an unprotected population—occurred. “My research involves the silencing of pox viral genes using RNA interference (RNAi),” explains Cadet. “What makes this relevant to study is because vaccinia
virus, a member of the Poxviridae family, is the vaccine agent used to vaccinate against variola virus, the virus that causes smallpox disease.” Cadet’s work is timely, possibly urgent. “Since the eradication of smallpox disease in the late 1970s, global immunization against it has ceased. In light of the events that have taken place post September 2001, there is heightened concern that variola virus could be used as a weapon of bioterrorism. “Due to this, there is a need to develop possible therapeutic interventions that could be used to protect the naïve population—should an intentional outbreak of smallpox occur.” (Naïve refers to the vulnerable population who are unvaccinated against smallpox. By example, indigenous people in the Americas were tragically vulnerable when the explorer Cortez brought the smallpox virus with him to the New World. And tribal Indians were decimated when British troops deliberately infected blankets during the French and Indian Wars in North America.) Gene Manipulation Meant to Silence a Killer Cadet continues her explanation on a positive note. “One promising approach is based on RNAi, a tool widely used for
As the largely self-taught British physician Edward Jenner proceeded in his scientific work, he began deliberately infecting human subjects by placing cowpox pus in an incision site. To put Jenner’s crude methods in perspective, remember that blood letting was very popular at the time. Like others had observed long ago, Jenner noticed that milkmaids in his English village who contracted cowpox seemed later to become impervious to the far deadlier smallpox. The penny had dropped: Jenner observed that the milkmaids achieved immunity. As a medical doctor, he soon used this information to immunize others. His methods may have been questionable, but the outcome revolutionized modern medicine. Jenner is credited within the vaccine world as the first to demonstrate the efficacy of his “new” vaccine.
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