Poultry disease is an international issue, but it's a particularly costly problem in developing countries.

Developing animals resistant to disease may be one of the long-term solutions. University of Georgia researchers in the Regenerative Bioscience Center have spent the last four years gathering data that could make the process a reality.

The team, which includes Steven Stice and Franklin West in the College of Agricultural and Environmental Sciences and Claudio Afonso at the Southeast Poultry Research Laboratory of the US Department of Agriculture's Agricultural Research Service, used a technology platform called shRNA to selectively stop the production of nucleic acids that cause disease, such as the Newcastle disease virus.

RNA is another type of nucleic acid, similar to DNA. Artificial 'short hairpin' RNA, or shRNA, structures can be made to 'turn off' specific genes in an organism.

Newcastle disease is a worldwide problem and is caused by one of the most deadly of all viruses that spreads between birds. Exotic Newcastle virus, the most devastating form of the virus, has been eradicated in the US and Canada. The milder forms of Newcastle are kept under control using vaccines.

The research team's process for enhancing disease resistance is potentially a much better form of disease protection than vaccination, because it introduces permanent genetic resistance that is transmittable to a bird's offspring, the researchers said. In contrast, many vaccines provide protection for a given period of time and must be re-administered periodically.

"With this technology, we can target specific regions used by the Newcastle disease virus that are critical for its survival," said Mr Stice.

"Preventing these lethal viruses from replicating in individual chickens may in the end reduce the overall level of virus transmission from one chicken to the next."

Multiple types of animals and disease could be targeted. This technology could also be applied to avian influenza and swine flu.

"Ultimately, you could have birds that are both avian influenza resistant and Newcastle disease virus resistant," said Mr West. "Theoretically, you may never have to vaccinate again."

Organised distribution of vaccine products can also present problems, especially in countries where farmers may not have a refrigerator or other means to store the vaccines at the temperature needed to keep the vaccine alive. This is particularly true in rural areas where backyard flocks may be a farmer's main source of income.

Shipping disease-resistant chickens produced in the US could be the best possible solution for many countries, Mr Stice said.

"We've taken many years to prove that this technology is viable," he continued, "and we're now ready to expand our work to the next stage."

The work was published recently in the Journal of the International Alliance for Biological Standardization.