National Institutes of Health (NIH) researchers are in the opening stages of testing on humans a new vaccine against H5N1, the pathogen behind the bird flu outbreak that has sickened at least 261 people since 2003.
The vaccine will also offer a first pass at using experimental DNA technology to make vaccines against flu. Instead of using weakened or killed viruses to prompt immunity in patients, the new vaccine uses chunks of the genetic material of the flu virus to get the body to react and hopefully form a defense against infection. The vaccine does not contain any infectious material and cannot cause infection.
The vaccine, due to be tested by NIH in 45 people, includes DNA from the "Indonesia" strains of H5N1.
At least 55 people contracted bird flu in Indonesia in 2006, more than three times the number in any other country, according to the World Health Organization. Forty-five of those people died.
"That is a hotbed of activity in terms of the virus persisting in animals and transferring to people. That's clearly one of the strains we're concerned about," says Gary Nabel, M.D., director of the Vaccine Research Center at the National Institute of Allergy and Infectious Diseases.
Currently, flu vaccines must be grown in hen eggs, a process that can take six months or longer to complete. But DNA vaccines can be produced in up to half the time, Nabel says.
DNA vaccines have the potential to allow for the rapid manufacture of vaccine, says Gigi Kwik Gronvall, Ph.D., an immunologist at the Center for Biosecurity at the University of Pittsburgh.
The technology — at least in principle — allows scientists to begin producing vaccine within days of identifying a dangerous disease strain.
"If it works, it would have huge advantages because you could modify your vaccine. That's the dream: to be able to respond to emerging disease quickly," she tells WebMD.
A Lot Of 'Ifs'
But scientists must first find out if the DNA vaccine works in humans. Two-thirds of the 45 patients in NIH's study will be given an active form of the vaccine to test it for safety and to see if it reliably prompts an immune response.
Finding out whether it can actually prevent infection with real-world H5N1 virus would be the next step.
"There are a lot of 'ifs' here," Gronvall says.
DNA vaccines against the human immunodeficiency virus (HIV) have already shown some ability to prompt immune responses in the short term.
"We really don't know if DNA vaccines will work for flu," Nabel says.
SOURCES: Epidemic and Pandemic Alert and Response (EPR), World Health Organization, Dec. 27, 2006. Gary Nabel, M.D., director, Vaccine Research Center, National Institute of Allergy and Infectious Diseases, National Institutes of Health. Gigi Kwik Gronvall, assistant professor of immunology, University of Pittsburgh School of Medicine, Center for Biosecurity.
By Todd Zwillich
Reviewed by Louise Chang