resistance a worry, page-10

re: csiro to enter history books 11 December 2002
New Generation Chicken Antibiotic Alternative

A new generation "natural" treatment to protect chickens against infection could soon phase out the use of antibiotics in the poultry industry which is good news for consumers concerned about their use.

A CSIRO Livestock Industries' research team has developed a way of delivering antibiotic alternatives - natural proteins called cytokines - into chickens.

CSIRO researcher, Dr John Lowenthal, says the use of antibiotics in animal industries has raised some concerns about the potential spread of antibiotic-resistant bacteria.

"A number of European countries have reacted to these concerns by restricting the use of antibiotics in food production animals," he says. "There is, therefore, a strong international push to develop new, environmentally-friendly methods to control disease in animals."

In 1990, CSIRO began an ambitious research program to find alternatives to antibiotics for the poultry industry. The focus was on using cytokines to enhance disease resistance in poultry. A significant advantage with this approach is the ability of the cytokines to provide protection against a range of different infectious diseases.

"Cytokines are proteins that are produced by the body. Their job is to improve the immune response during infection and help combat disease. As such, they are excellent naturally-occurring therapeutics," Dr Lowenthal says.

"We showed that when chickens were treated with cytokines their health improved and as a consequence they gained weight more quickly. The problem was identifying how we could safely and effectively deliver this treatment to the 400 million chickens grown commercially each year in Australia."

According to CSIRO researcher, Dr Mike Johnson, the solution involved using viruses called adenoviruses to carry the cytokines into chickens.

"The adenoviruses we are using are similar to vaccine strains commonly used in the poultry industry. Using these adenoviruses is ideal in terms of maintaining biosafety standards because they are harmless to the animal and only infect one species," Dr Johnson says. "For example, a chicken adenovirus will infect only chickens, but not humans or other animals."

Another safety factor is that the adenovirus and cytokines remain in the chicken for only a few days while the protective effect lasts much longer. As a result, fully-grown chickens are completely free of the treatment.

A big plus is the way treatments can be delivered to animals.

Needles are no longer necessary - instead treatments can be mixed in with food or water or simply sprayed on.

"Numerous animal trials, performed at CSIRO's secure animal facilities, showed that treating chickens with an adenovirus carrying a cytokine - chicken gamma interferon - led to improvements in growth performance," Dr Johnson says.

An Australian research and development company, VectoGen Limited, a subsidiary of the Australian animal health company, Imugene Limited, recently acquired exclusive worldwide licenses from CSIRO to this new technology.

VectoGen's Chief Executive Officer, Dr Adrian Hodgson, says the new treatment will assist with the reduction in the use of antibiotics as an in-feed additive and assist Australian livestock producers in providing sustainable production of safe, high-quality food products.

"The chicken cytokine treatment is one of a range of products VectoGen is developing for the pig and poultry health markets," says Dr Hodgson.

Dr Jeff Fairbrother, Executive Director of the Australian Chicken Meat Federation, says the Australian poultry industry keenly awaits the release of this novel technology.