December 7, 2006

US develops first egg-injected poultry vaccine

An Auburn University, US veterinary professor in collaboration with researchers at Vaxin of Birmingham has developed the first "in ovo," or egg-injected, vaccine to protect chickens against avian influenza.

The research, which has been published in the scientific journal "Vaccine," would provide 100 percent protection once an outbreak's strain is determined, said Dr Haroldo Toro, the university professor.

The researchers inserted a gene from a low pathogenic avian flu virus strain (H5N9) into a non-replicating human virus, which was then injected into developing chicken embryos still in the egg.

When protection induced by the vaccine was tested against two highly pathogenic avian flu viruses, a Vietnam H5N1 strain and a Mexican H5N2 strain, the results showed 68 percent and 100 percent protection, respectively.

The strains have slightly different genetic makeups which account for the different percentages in protection, said Toro, who is also collaborating on this project with the Southeast Poultry Research Laboratory.

In the case of an outbreak of avian influenza, mass vaccination programmes around the perimeter region would help to reduce the risk of further dissemination of the field virus to neighbouring areas.

Most poultry operations have already automated injection machines to vaccinate against Marek's disease, injecting up to 40,000 eggs per minute. Since the vaccine is produced through cell cultures, researchers could ensure enough vaccine for thousands of birds, pointed out Toro.

He said the procedure would be easier than producing inactivated, or killed, vaccines, which require replicating the live avian influenza virus in egg embryos and individual delivery by injection.