Bird flu jab for chickens could halt spread of the virus

Jan 29 2006

U.S. researchers say they have produced a vaccine in less than a month which completely protects chickens from the deadly H5N1 virus.

They say the vaccine is an economical way to stop the spread of the bird flu.

The team at the University of Pittsburgh is now putting together a plan to test the vaccine in humans, but before that can be done Dr. Gambotto says full-scale clinical trials will be needed.

Dr. Andrea Gambotto assistant professor of surgery, molecular genetics, and biochemistry at the University of Pittsburgh School of Medicine, who led the study, says it took them about 30 days to make the vaccine from the time they received the sequence information from CDC in Atlanta, and the vaccine he says is very potent.

Although the virus remains essentially a disease in birds which does not pass from humans to humans, 152 people had been infected usually through close contact with sick birds and to date 83 have died.

Experts fear it may mutate and then be able to pass from person to person, sparking a pandemic that could kill millions around the globe.

As a rule influenza vaccines for both chickens and humans take months to make and are grown in chicken eggs.

The process is an uncertain one and the vaccines do not provide perfect protection.

Many experts believe the way forward is cell-based production, by growing the vaccine in batches of human cells grown in the lab instead of in eggs.

The spread of the H5N1 virus has made the need for better vaccine technology urgent.

It is unclear just how H5N1 will mutate, but experts agree it will be impossible to start making a vaccine against it until the pandemic strain emerges.

Gambotto and his team believe their approach will provide a way to start making such a vaccine quickly.

Apparently in their work they did not use the actual H5N1 virus but rather the genetic sequence data received from the Centers for Disease Control and Prevention (CDC).

By artificially generating the DNA coding for the hemagglutinin gene which controls a protein found on the surface of all influenza viruses and provides the "H" in a virus's name, they obtained the portion they thought was important for immunity.

Gambotto says they did not manipulate the actual H5N1 virus themselves, making it safe to generate such a vaccine.

The artificial DNA was then spliced into a human adenovirus, a common cold virus.

They say tests in mice and chickens showed it provided partial protection when given nasally, and 100 percent protection against H5N1 when injected.

The vaccine produced a dual immunological response where the body generated both antibodies to neutralize the virus, and T-cells, a kind of immune cell that also attacks viruses.

Gambotto says this means the vaccine may work against mutated versions of the flu virus, something current vaccines cannot do, and is why flu vaccines must currently be reformulated every year.

Gambotto is optimistic that the nasal vaccine might work better in people than it did in animals, because the vaccine uses a live human adenovirus.

Gambotto and his team are working with the U.S. Food and Drug Administration to gain approval for human trials.