Poultry professionals from industry and academia recently had the opportunity to learn about this new approach to fighting bacterial diseases such as necrotic enteritis caused by Clostridium perfringens and the research investigations supporting it. Amlan International, a leader in developing advanced solutions that enhance intestinal health and productivity in livestock, hosted leading experts in antivirulence therapy during a special symposium at the 2018 Poultry Science Association’s Latin American Scientific Conference in Sao Paulo, Brazil.

“An antivirulence approach to controlling and even preventing bacterial diseases is a significant paradigm shift in the post-antibiotic-growth-promoter era,” said Hongyu Xue, MD, PhD, Director of Life Sciences for Amlan International. “The symposium highlighted the significance of this new concept and was designed to increase awareness for the topic among animal health practitioners, which it did.”

What is antivirulence therapy?

Tom Defoirdt, PhD, a leading microbiology researcher with the University of Ghent and one of the symposium speakers, explained that bacteria produce or express a variety of molecules, known as virulence factors, which help them colonize the host animal’s gut and damage the intestinal epithelial cells. These factors range from fiber-like structures that enable bacterial attachment to host cells to toxins that can inhibit protein synthesis, damage cell membranes or activate immune responses. These virulence factors are essential for infection to occur. But if bacteria are prevented from producing virulence factors or the expressed factors are neutralized, the bacteria cannot cause infection. Consequently, antivirulence therapies offer an important alternative strategy for controlling bacterial diseases.

Dion Lepp, PhD, a biologist with the Agriculture and Agri-Food Canada, Guelph Research and Development Center, and symposium speaker told attendees that unlike traditional antibiotics which kill or inhibit bacteria and can lead to drug resistance, antivirulence therapies interfere with bacterial virulence mechanisms without placing selective pressures that are associated with traditional antibiotics. For a number of disease-causing bacteria, quorum sensing plays a key role in regulating virulence and therefore offers a potential intervention point for antivirulence therapies.

An economic and disease challenge for poultry producers

For decades, growth-promoting antibiotics have been routinely used in commercial poultry feed to control necrotic enteritis caused by C. perfringens and ensure bird performance. However, in those countries where antibiotic growth promoters have been reduced or phased out, necrotic enteritis has reemerged as a significant problem. On average, necrotic enteritis is estimated to cost producers US$0.05 to US$0.063 per bird.

Technology that leverages an antivirulence approach to minimizing enteric disease is available to poultry producers now. Dr. Xue shared findings from recent studies conducted at Amlan’s Innovation Center that showed a unique activated enterosorbent mineral, Calibrin®-Z, can adsorb and degrade chemical signals (i.e., quorum sensing molecules) used by bacteria to communicate with each other. Further, Amlan’s scientists generated multiple lines of evidence demonstrating this sorbent mineral can neutralize a diverse repertoire of secreted or surface-exposed virulence factors that compromise bird intestinal health and productivity.

“Often the key challenge is an inherent narrow spectrum of activity for the target bacteria,” Dr. Xue said. “But our adsorbent mineral has a broad spectrum of activity, so it can be used to target a large number of antivirulence factors. We’re really excited about the possibilities.”

At a time when poultry producers are looking for alternatives to antibiotics to help maintain the health of their flocks, feed additives that target bacterial virulence factors can be a valuable tool for promoting animal health. Livestock producers can look forward to new innovative products backed by research from Amlan International.

An example of antivirulence therapy in action. Bacteria release autoinducers (quorum sensing signal molecules) into their immediate environment to monitor changes in population density and to “talk” to each other during quorum sensing. Calibrin-Z, a unique activated mineral available from Amlan International, has been shown to adsorb and degrade these signal molecules, disrupting quorum sensing and, ultimately, bacterial virulence

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