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Salmonella May Spread Further by Becoming Less Virulent

The researchers also discovered that Salmonella has evolved a gene and mechanism to block the sickness-induced anorexic response in its host. By inhibiting this response, the bacterium was less virulent in its host, did not spread to systemic tissues, and promoted survival of the host and its transmission to new hosts. The mechanism that Salmonella uses to inhibit sickness-induced anorexia involves manipulating the gut-brain circuitry that controls appetite. “Salmonella inhibits the inflammatory response in the intestine, preventing its signaling to the appetite control center in the brain via the vagus nerve, thereby preventing the induction of anorexia,” summarized Dr. Ayres.

Overall, the results of this study highlight how a bacterium typically known as a pathogen has evolved a mechanism to inhibit its ability to cause disease and allow survival of its host in order to promote its own spread to new hosts.
Dr. Ayres emphasized that these findings not only provide new appreciation for the role of nutrition in infection transmission, but also suggest there may simpler ways to treat infectious diseases—by using nutrition, for example. This is especially important now, given the rising problem of antibiotic resistance, she noted.
In future studies, Dr. Ayres added that she and her team would like to investigate whether microbial members of the human microbiome have evolved similar mechanisms to manipulate the gut-brain circuitry of their hosts to regulate appetite. They would also like to identify which specific nutrients regulate transmission of pathogens, and which ones inhibit invasion of pathogens. “If we can dissociate the two, we can develop new nutrient-based therapies to promote survival of infections and control of disease transmission,” she concluded.
Dr. Parry graduated from the University of Liverpool, England in 1997 and is a board-certified veterinary pathologist. After 13 years working in academia, she founded Midwest Veterinary Pathology, LLC where she now works as a private consultant. She is passionate about veterinary education and serves on the Indiana Veterinary Medical Association’s Continuing Education Committee. She regularly writes continuing education articles for veterinary organizations and journals, and has also served on the American College of Veterinary Pathologists’ Examination Committee and Education Committee.
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