Aug. 16, 2010 – Necrotic enteritis (NE) is the most common disease encountered by poultry farmers today and is estimated to cost the international poultry industry US $2 billion each year. The disease is currently controlled by the prophylactic use of antibiotics, a practice that has now been banned in Europe, which quickly lead to a surge in NE cases there.
Concerns by the poultry industry that a similar regulation will be implemented in North America have spawned intensified research into this disease, with the ultimate goal of developing alternative control strategies. Now a major breakthrough by Agriculture and Agri-Food Canada (AAFC) researchers Dion Lepp and Joshua Gong at the Food Research Centre in Guelph, Ontario, in conjunction with other researchers, has identified the gene clusters likely responsible for this deadly disease and is bringing the research one step closer to developing effective controls.
NE is caused by Clostridium perfringens, a species of bacteria that typically exists as a harmless inhabitant of the gastrointestinal tract. Until recently, it was believed that NE resulted from the production of alpha-toxin (the same toxin responsible for gas gangrene in humans), one of many toxins produced by this bacterium. However, this has been called into question recently and another toxin, NetB, has been implicated.
Further to the discovery of NetB, the AAFC scientists have collaborated with colleagues at the University of Guelph and the University of Arizona and identified a set of approximately 30 genes in NE – causing isolates of C. perfringens through a comparative genomic approach. These genes are divided into three major clusters, the largest of which also includes the NetB toxin.
“Surprisingly, two of these clusters are located on plasmids, small segments of DNA that can be easily transferred from one bacterium to another,” explains Lepp. “These findings suggest that NE is caused by a number of genes that work together to generate the disease, as opposed to just one toxin, and that these genes may be passed on from one C. perfringens isolate to another.”
“This is breaking news in the field and establishes a milestone in NE research,” emphasizes Gong. “The new discovery will have a significant impact on the direction of future research by influencing the view and thinking of researchers towards the disease and its control. Further identification of the function of these genes and their role in the disease process may lead to novel innovations for controlling NE disease.”
The results of the new discovery have been published in a prestigious biological journal, PLoS ONE (2010, Vol 5(5), e10795). The research is funded by Agriculture and Agri-Food Canada, the Ontario Ministry of Food and Rural Affairs, the Poultry Industry Council, the United States Department of Agriculture and Pfizer Animal Health.
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