What’s Happening in Salmonella Research

“Our goal was to develop a novel Salmonella control strategy that promotes the establishment of an intestinal microbiota in the chicken that prevents colonization by pathogenic bacteria and enhances the mucosal immune response to Salmonella vaccination and challenges,” Dr. Hassan relates. “To that end, our objectives were to characterize the changes in the chicken’s gut microbiome during Salmonella infections and identify members of the microbiota associated with decreased Salmonella colonization; and to develop an optimized control program that promotes resistance to colonization and the development of strong mucosal immunity virulent strains of Salmonella enterica.”

Funded by a $2.5 million USDA NIFA grant that was awarded in 2012 and runs through June 30, 2018, Dr. Hassan, his NSCU colleagues, and collaborators at the University of North Carolina-Chapel Hill (UNC-CH) have used an attenuated strain of Salmonella, which was developed by his students during 2007 through 2010 and patented in 2012, as vaccine. “The strain is different than the current vaccines and its authenticity and efficacy were first tested in the mice model of salmonellosis,” Dr. Hassan relates, noting that the mechanism of action hasn’t been published, so is yet confidential. “We also sequenced the complete genome of this patented Salmonella vaccine strain.”

The research team used the novel vaccine strain in its poultry studies alone, and in combinations with other reagents, such as prebiotic galacto-oligosaccharides (GOS), for modulating the gut microbiome of egg laying chickens.

“We isolated and characterized several poultry-specific probiotic organisms from the healthy experimental birds and selected three isolates for complete genome sequencing,” Dr. Hassan points out.

The researchers identified the composition and the development of the chicken gut microbiome as a function of age, vaccination, adding prebiotic GOS to the diet, adding poultry-specific probiotic isolates to the diet, and combinations thereof.

Dr. Hassan says these efforts are based on the fact that the gut microbiota plays an important role in the digestion of complex plant fibers and polysaccharides; and the microflora also provides protection against colonization by invasive pathogenic organisms (colonization resistance).

“We also examined the effects of these treatments on the chicken’s immune system,” Dr. Hassan continues. “Based on our results, we conclude that vaccination and modulation of the gut microbiome enhanced the bird’s ability to resist Salmonella infections. We currently have work in progress to identify the effects of these treatments on gut metabolites and how they contribute to mechanism(s) for resistance to pathogens.”

An article about the vaccine was just submitted to a peer reviewed journal in March 2018.

Dr. Hassan says the NCSU Office of Technology Commercialization and New Ventures has signed a confidential disclosure agreement with a commercial vaccine production company to evaluate and discuss the data. “We don’t know when and if our new vaccine will be available commercially,” he notes.

Youth Education and Outreach

An additional major component of this research, Dr. Hassan points out, has been to work with professional educators and extension 4-H faculty at NCSU, who have been co-principal investigators, to develop educational materials for K-12 students and 4-H groups to teach consumers about food safety, the science behind preventing foodborne disease, and their role in preventing salmonellosis.

“For this we set out to develop innovative K-12 curriculum material in subjects related to food safety, disease transmission, and next generation genetic research to engage students in agricultural sciences and communicate their role in food safety,” Dr. Hassan relates. “We aimed to develop instructional materials based on the 4-H national standards to communicate and teach 4-H members the technology and science used to produce safe food and their responsibilities in preventing foodborne disease.”

In collaboration with the Kenan Institute at NCSU, Dr. Hassan’s team selected nine K-12 school teachers from around the state of North Carolina to participate in the program. “These nine ‘Food Safety Kenan Fellows’ spent the summers of 2012 and 2013 working in three different research labs, the microbiology and immunology labs at NCSU, and the Microbiome Core Facility at UNC-CH, learning about the microbiological, immunological, and the molecular biology/genome sequencing aspects of food safety,” Dr. Hassan says. “By 2014, the Food Safety Kenan Fellows developed and field tested three food safety curricula for elementary, middle, and high schools.”