Smallpox, a devastating disease caused by the variola virus, was eradicated in 1979 through the efforts of the World Health Organization (WHO). Currently, infectious variola (one of a class of viruses called orthopoxviruses) is known to exist only in two WHO-sanctioned repositories, one in Russia and the other in the United States. However, there is concern that undisclosed reference stocks of the virus may exist, and its potential as a biological weapon has led to the production and stockpiling of smallpox vaccine and the immunization of some healthcare workers.
The USAMRIID team, led by Jay W. Hooper, Ph.D., based its DNA vaccine on four genes from vaccinia virus--the same virus used in Dryvax, the licensed smallpox vaccine. Because Dryvax contains live virus, it carries a high risk of complications for people with suppressed immunity and other conditions. A DNA vaccine would not have the adverse side effects commonly associated with a live virus vaccine.
"This work represents important progress toward a smallpox vaccine that is as effective as the current product, but safer," said Colonel Erik A. Henchal, commander of USAMRIID. "It is yet another example of how USAMRIID research to protect military service members can contribute to the overall public health."
As smallpox no longer occurs naturally, experimental vaccines cannot be tested for their ability to prevent the disease in humans. Thus, licensing of future vaccine candidates will include studies of immune response and protection in nonhuman pri
Contact: Caree Vander Linden
US Army Medical Research Institute of Infectious Diseases