WASHINGTON -- In a multi-institutional study, Department of Veterans Affairs (VA) researchers have found an oral drug that kills smallpox and other viruses and could be the answer to saving thousands of lives during a bioterrorism attack or widespread epidemic.
The drug, called hexadecloxypropyl-cidofovir (HDP-CDV), stops the smallpox virus from replicating and spreading. To date, the drug has only been tested in mice and is not available for human use. Researchers at the U.S. Army Medical Research Institute of Infectious Diseases (USAMRIID) are conducting further studies.
"This is a big step for VA and the country," said Secretary of Veterans Affairs Anthony J. Principi. "The discovery combines VA's extensive, national research program with VA's mission to respond to national emergencies, which was put to a dramatic test on September 11."
Fear of bioterrorism soon followed the September attack and the smallpox virus was a major concern. Caused by the variola virus, smallpox is highly contagious. Additionally, there is concern that even people who were vaccinated before 1972 are no longer immune to the disease. USAMRIID researchers, headed by Dr. John Huggins, screened hundreds of existing drugs to combat smallpox at the Centers for Disease Control and Prevention in Atlanta before identifying an existing compound called cidofovir.
"HDP-CDV is a potent derivative of cidofovir," said developer of the new drug, Dr. Karl Y. Hostetler, director of the Endocrine and Metabolism Clinic at VA San Diego Healthcare System (VASDHS) and professor of medicine at the University of California at San Diego. "However, cidofovir must be administered intravenously, thus limiting its fast application in an emergency. If you've got thousands of people exposed to smallpox, oral treatment would be far more effective."
If continuing studies support HDP-CDV's effectiveness and safety, the drug could be given in pill or capsule form over five to 14 days for prevention or treatment of smallpox in people exposed to the disease, said Hostetler.
The VA and University of California work was done in collaboration with research groups headed by Huggins and Dr. Earl Kern, University of Alabama, Birmingham. The effort was initiated in 1999 when the National Institute of Allergy and Infectious Diseases (NIAD) asked the VA and UCSD team to develop an oral version of cidofovir.
Hostetler, along with Huggins and Dr. James Beadle, also a VA researcher and UCSD professor, presented their results at the 15th International Conference on Antiviral Research in Prague, Czech Republic, on March 20. Not only were the smallpox findings presented, but Huggins reported the results of HDP-CDV therapy in mice infected with cowpox, a pox virus closely related to smallpox. Huggins found that five daily oral doses of HDP-CDV provided complete protection from the lethal cowpox infection.
"Until now, the eradication and control of smallpox relied on vaccination," Hostetler said. "The results from this research suggest that we may be able to treat and contain future outbreaks of smallpox with simple oral medications."
Hostetler's research was supported by grants from DoD, the National Institute of Allergy and Infections Diseases, the National Eye Institute and the VA San Diego Healthcare System.
"Make no mistake, what the VA health care system does concerns not only the health and well-being of veterans, but also the strength of the nation," said Principi. "We have become integral to the country's health -- in direct care, in research, in education and in homeland security."
