Navy Researchers Test Anti-Malaria Vaccine
By Douglas J. Gillert
American Forces Press Service
WASHINGTON, Nov. 9, 1998 Malaria felled more combatants during the Vietnam War than bullets, and the disease has since reached global epidemic proportions. Health organizations estimate up to 5 million people have died of AIDS in the past 15 years -- but malaria killed nearly 50 million.
Aside from Bosnia, the majority of U.S. troop deployments are to malarial regions. In Somalia, for example, malaria was the top cause of troop casualties. Under the most heavily enforced discipline for taking medications, one Marine unit suffered a 10 percent attack rate in a single month.
These are the kinds of statistics that have driven Navy Dr. (Capt.) Stephen Hoffman's career. As director of the malaria program at the Naval Research Institute, Rockville, Md., he is perhaps DoD's single most expert malaria researcher. His highest priority has been to develop an effective vaccine that prevents malaria. In October, he moved a step closer to realizing his goal.
Hoffman's team of military and civilian researchers successfully tested a DNA vaccine on healthy humans that potentially could be used to battle a host of infectious diseases, including malaria, AIDS, dengue fever and tuberculosis. It may also be effective against highly fatal diseases such as Ebola and against cancer and biological warfare agents. Science magazine reported on the research Oct. 16, a day after Hoffman discussed the findings in a Pentagon press conference.
"The purpose of this study was to determine if DNA immunization is safe, well tolerated and generates an immune response in normal humans," Hoffman said. "We established this, so our next step is to develop a vaccine that will provide protection."
The research team immunized 20 healthy volunteers with malaria DNA vaccine. The majority developed potent "killer" T-cells, which defend the body against the disease.
"We used malaria as a model system to test this exciting new technology, because it is the most important infectious disease threat to our operating forces," Hoffman said. "The significance of this demonstration, however, is in the proof of principle that allows us to advance toward a new era of vaccines."
Licensing of a DNA vaccine is still years away, Hoffman said.
Because the U.S. military has often deployed to malarial areas this century, DoD has been at the forefront in advancing malaria care. "All malarial drugs licensed and used in the United States and much of the world were developed by DoD," Hoffman said. Currently, service members deployed to malarial areas take either Mefloquine or Doxycycline. These drugs don't always work, however, and researchers are discovering more and more drug-resistant strains. The DNA vaccine would be far more effective, Hoffman said.
The malaria parasite is a microorganism with multiple stages of life. In humans, it lives near a blood stream in the liver, as well as inside and outside cells in the blood stream. T-cells generated by the DNA vaccine would attack and kill infected cells.
The parasite enters the body through mosquito bites. Uncomplicated malaria causes high fevers, chills, headaches and muscle pain. Treated properly, victims are laid up anywhere from a few days to several weeks. If malaria isn't treated properly -- or if medication fails -- victims may develop kidney, liver and lung problems.
The most serious complication affects the brain, and victims at this advanced stage become disoriented, delirious and often comatose. Hoffman said it's not unusual, however, for malaria victims to hallucinate within a week of becoming ill, but then fully recover.
He foresees a vaccine that would last at least a year and, ultimately, one that would last a lifetime. Giving service members shots before they enter a malarial zone would eliminate the problem of unused or underused medications and help combat units sustain higher operational capability, he said.
The Navy has collaborated for five years with Vical Inc., a San Diego biotechnology company that discovered and patented the new vaccine technology. Support for the project came from DoD's Military Infectious Disease Research Program, the Office of Naval Research's Advanced Technology Demonstration Program and the pharmaceutical company Pasteur Merieux Connaught.
Hoffman's team includes Drs. Ruobing Wang, Denise L. Doolan, Jennifer Ng, Martha Sedegah and Yupin Charoenvit; Navy Cmdrs. Richard Hedstrom, Thong P. Le, Walter Weiss and Trevor Jones; Drs. Jon Norman, Peter Hobart and Michal Margalith of Vical, Inc.; Army Capt. Kevin Coonan of the Army Medical Research Institute of Infectious Diseases; and Charles De Taisne of Pasteur Merieux Connaught.