June 25, 2021

Ourania Raftopoulou (North Carolina State University)

Impact of the growth history of a foodborne pathogen on its virulence

Spring 2021 Graduate Student Award in Pathogenic and Commensal Organisms


Listeria monocytogenes (Lm) remains a serious foodborne hazard that compromises the health of many Americans annually. At especially high risk are pregnant women and their fetuses, the elderly, and immunocompromised persons. Lm is notorious for its capacity to grow even at low temperatures and form persistent biofilms in food processing plants and equipment from which it transfers to foods. Foods that are considered ready-to-eat (e.g., fresh produce, ice cream, dairy, deli meats) are at especially high risk for contamination with Lm. However, little is known about the impact of biofilm growth or temperature on virulence of Lm. In order to control future outbreaks of listeriosis and enhance food safety, it is critical to further elucidate aspects of virulence of this persisting pathogen. This proposal, which specifically targets TriCEM’s mission to expand knowledge on pathogens’ virulence, aims to assess the virulence of Lm in vivo using Galleria mellonella (Gm), a promising invertebrate model for virulence. The goal is to elucidate the impact of biofilm growth at reduced temperatures on virulence. Virulence assessments will target both sides of the pathogen-host interaction. They will include transcriptional assessments of key genes associated with Lm’s virulence and genes related with Gm’s immune response when the infection occurs by either planktonic or biofilm cells at optimal temperature for Lm (37 C) or at a reduced temperature (15 C). The data acquired will promote evolutionary medicine through elucidating Lm virulence and will provide knowledge for future research on combatting listeriosis with the development of innovative antimicrobial agents and strategies.