Army Scientists Explore New DNA Vaccine Delivery Method

By Navy Lt. Jennifer Cragg
Special to American Forces Press Service

June 1, 2009 - Army scientists are studying a new DNA vaccine delivery method that will one day be needle-free and painless, a senior Army research scientist at Fort Detrick, Md., said. "DNA offers a number of advantages over conventional vaccine approaches, especially with regard to biodefense vaccines," Connie Schmaljohn, senior research scientist at the U.S. Army Medical Research Institute of Infectious Diseases, told "Armed with Science: Research and Applications for the Modern Military" listeners during a May 27 audio webcast.

"This is important when rapid vaccine development is needed for a newly emerging disease threat or possibly for a genetically engineered biological warfare pathogen," Schmaljohn, who holds a doctorate in virology, added.

One of the newest DNA vaccine delivery methods relies on technology known as the "gene gun," which is capable of delivering the vaccine directly into cells. The needle-free vaccination method is more cost-effective and less painful for the recipient.

"The DNA is first coated onto very, very tiny gold beads, and those gold beads with the DNA are then put inside of a plastic device that's about the size of a small flashlight," she explained. "Inside that device is also a little canister of compressed helium gas. When the trigger of the gene gun device is pushed, the gas is released and it propels the gold coated with the DNA out of the device into the skin of the vaccine recipient."

USAMRIID is conducting a human study of DNA vaccines using this delivery method. Schmaljohn's research team has isolated small amounts of DNA from the Hantaan and Puumala viruses -- known health threats to U.S. troops stationed in Europe and Asia -- to develop the vaccines. Both vaccines are in Phase I clinical testing, the first step toward licensure by the U.S. Food and Drug Administration.

"Its main goal is actually to prove that the vaccine is safe in humans, but of course, we're also interested in determining if it's inducing an immune response," she added.

"The hantaviruses, once they infect humans, can cause one of two serious human illnesses: hemorrhagic fever with renal syndrome, which occurs in Asia and Europe, or hantavirus pulmonary syndrome, which occurs in the Americas," Schmaljohn said.

USAMRIID is producing a DNA vaccine for the Asian and European hantaviruses that can cause hemorrhagic fever with renal syndrome. This disease first was recognized as a threat during the Korean War.

"Today there's more than 100,000 cases of hemorrhagic fever with renal syndrome each year, with the highest number occurring in China, Russia ... Scandinavia and other parts of Europe," Schmaljohn said.

These viruses are found in many types of rodents, including rats, field mice and meadow voles.

"They're transmitted to humans in the aerosols of rodent's urine, feces and saliva," Schmaljohn explained. "The rodents that carry these viruses are persistently infected, and they show no signs of illness."

She added that over tens of thousands of years, these viruses and rodents have formed a mutually exclusive relationship in which both have adapted to one another. While the virus doesn't appear to affect the rodents' health, the virus does pose significant risk to humans.

Schmaljohn reminded "Armed with Science" listeners about the importance of medical research to the health and well being of the nation.

"Without continuously pushing the envelope of science, we will not be able to adequately respond to new disease threats," she said.

(Navy Lt. Jennifer Cragg serves in the Defense Media Activity's emerging media directorate.)