Researchers at the University of Pittsburgh have genetically engineered an avian flu vaccine from components of the deadly H5N1 virus. The Journal of Virology reports that the new vaccine completely protected all mice and chickens immunized against the disease.
The vaccine combines a live virus that causes the common cold with genetic material from the H5N1 virus and is grown in cells. This differs from the conventional procedure that uses a dead virus cultured in eggs.
Dr. Andrea Gambotto of the University of Pittsburgh Medical School is lead author of the study. He says the new vaccine offers potentially broader protection than one targeted at a specific flu strain.
"If the virus changes a little bit while you are stockpiling it, you may have to start from scratch to develop another vaccine and maybe you have used up the eggs that culture the vaccine. You may end up with nothing or be incapable of producing a new one," he says.
The study finds that one form of the recombinant virus creates several types of immunity against the H5N1 virus, making it an attractive candidate to prevent the spread of the disease in poultry and perhaps among humans. Dr. Gambotto says if a pandemic hit, a strain-specific vaccine could be developed within a month. "The vaccine can still change a little bit," he says. "We still think that the vaccine will cover those type of changes."
Dr. Gambotto expects to begin human clinical trials of the vaccine within six months. He says the genetic engineering approach offers great promise not just against the H5N1 virus, but against other emerging diseases.
Dr. Gambotto is optimistic that the vaccine will be effective in humans. 'The only thing that I don't know is how much vaccine I need to give to the people to generate immunity which relates to protection," he says
An estimated 150 to 200 million birds have either died in outbreaks or been killed in an effort to prevent the infection from spreading. 170 people have caught avian flu from infected poultry, and half of them have died. The virus must first mutate in humans before it can be passed from person to person.
