Human Tests for Bird Flu Vaccine Start
Experimental Vaccine Contains DNA Pieces of H5N1 Strain
Jan. 3, 2007 -- Government scientists say that an experimental vaccine
technology could give them a jump on the constantly mutating bird flu
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
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, MD, 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, PhD, 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
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