POULTRY SCIENTISTS USE VIRUSES TO FIGHT BACTERIA

FAYETTEVILLE, Ark. - Faced with the potential loss of traditional antibiotics, scientists at the University of Arkansas and the USDA Agricultural Research Service are updating century-old technology to fight illness-causing bacteria in poultry by infecting them with viruses known as bacteriophages.

"There has been growing concern that use of antibiotics has been causing an increase in antibiotic-resistant strains of bacteria that cause diseases," ARS researcher Bill Huff said.

"We felt it was important to find alternatives to antibiotics," he said. "Bacteriophages give us another tool to battle disease-causing bacteria and reduce pressure on bacteria to develop resistance to antibiotics."

UA poultry scientist Billy Hargis said two European scientists working independently in England and France discovered bacteriophages almost 100 years ago. The science of the day was inadequate for developing a reliable medicine, but modern advances in science and concerns about antibiotics have sparked a renewed interest in them.

"Bacteriophages are very specific viruses," Hargis said. "They don't harm people, animals or plants, only a narrow range of bacteria."

Hargis is working with bacteriophages that attack Salmonella and Huff is working with bacteriophages that attack E. coli. In both studies, they are learning to use them to protect poultry from respiratory infections.

Huff said bacteriophages are much smaller than the bacteria they attack. When one comes into contact with a target bacterium, the phage attaches to an anchor site on the cell's surface. It penetrates the cell wall and membrane and injects its DNA into the host. The DNA rewrites the cell's reproductive programming to replicate bacteriophage. It also produces an enzyme that "lyses" the cell - bursts it open, killing it, to release new virus.

Hargis said this entire life cycle is usually completed in about 30 minutes.

Both scientists found aerosol spray offered the best means of delivering the phages to large numbers of chickens or turkeys. They also found a large dose was needed to provide effective and consistent protection, but they are easy to amplify in a lab to sufficient numbers.

Hargis and Huff have demonstrated that bacteriophages can protect poultry from respiratory infections, but they are still working to see if the viruses can cure birds that are already sick. They are also trying to find a way to get bacteriophages into the birds' intestinal tracts, where they can fight the bacteria that can contaminate poultry meat during processing and cause a health risk to humans.

Hargis said bacteriophages are safe and environmentally friendly.

"Bacteriophages are ubiquitous - they occur naturally everywhere, even on your hands and face," he said. "They're not something new being grown in the lab that could get out and wreak environmental havoc.

"In the U.S., we use only defined cultures," Hargis said. "That means we know exactly what organisms are in it, what they'll do and that nothing unknown is in there."