Of the seven vaccines under development by the Poultry CRC, it is its search for a vaccine against necrotic enteritis (NE) that is being monitored most closely by the global poultry community.
“An effective NE vaccine will save at least two billion US dollars each year for the global chicken meat industry, based on an estimate made in the year 2000,” explained Lloyd Thomson, the CRC’s Commercial Manager.
Why is this so?
“Because controlling NE is the key reason for many producers to use in-feed antibiotics,” explained Lloyd.
Globally, NE is the most common and financially devastating bacterial disease affecting modern broilers. Caused by the bacterium Clostridium perfringens, NE causes severe damage to the chicken’s intestinal mucosa, resulting in mortality and morbidity. The sub-clinical forms of NE, which do not produce severe lesions, actually account for over 90% of the chicken growers’ economic losses.
“You can, of course, use antibiotics to treat sick animals,” said Poultry CRC CEO, Professor Mingan Choct, “but subclinical NE comes and goes like a storm, with infections typically lasting between four and seven days. This is far too long for a modern broiler to make up the loss in feed conversion ratio and growth before pick up. Therefore, early control is essential. This may become even more problematic if in-feed antibiotics are banned.”
“Recent studies have indicated some degree of protection against NE using toxoid vaccines,” said Lloyd, “but with our discovery of NetB, there is now hope of a truly effective vaccine against NE.”
Poultry CRC PhD student, Dr Anthony Keyburn, discovered the new toxin, NetB, demonstrating that it, and not alpha-toxin (another type of toxic chemical produced by Clostridium perfringens and released into the chicken’s gut), was the primary virulence factor in NE. His work overturned a 30-odd year old dogma that alpha-toxin was the culprit for NE in chickens.
The Poultry CRC is now undertaking larger scale challenge trials, exploring vaccine delivery methods, investigating genetically modified organism (GMO) vaccine registration and a host of other activities to get the first truly effective necrotic enteritis vaccine to the poultry industry.