Title: EPI investigator
Department: Molecular genetics and microbiology
Curriculum vitae: PDF
Research Interests: Structural microbiology, type III secretion systems, enterohemorhhagic E. coli, shiga toxins
Jorge Girón came to EPI from the University of Arizona in the spring of 2009, he holds a joint position between EPI and UF's College of Medicine, department of molecular genetics and microbiology. His research focuses on the structural microbiology of pathogenic E. coli O157:H7, and determining the role of specific molecular structures in their pathogenecity and ability to colonize new hosts. His current work has focused upon discovering, describing and understanding new types of pili, hairlike protein structures that extend outward from the exterior surface of gram-negative bacteria, and establishing links between genetic expression of pili and virulence. Dr. Girón has contributed to the discovery, description and understanding of at least three new types of "type-IV pili" that aid the agent in adhering to different surfaces.
A large part of his research deals with enterohemorhhagic E. coli (EHEC) and understanding how these organisms move through the environment, including their commensal existence in the intestinal tracts of bovines, and their presence and persistence in agricultural settings including the production and packaging of commercial spinach. He is exploring the mechanisms and processes by which these E. coli colonize leafy vegetables such as spinach, due to recent outbreaks that have caused widespread threats to public health, and called attention to vegetable packaging standards. Taking a comprehensive view of the bacteria's range of hosts, Dr. Girón is also studying the different structural mechanisms by which these E. coli produce pili to adhere to human intestinal epithelium, how they colonize hosts and how they cause disease. By experimentally determining which pili types are important to which host-environment (plant, animal or human), he and his team are seeking to establish which specific genes are responsible for producing host-specific pili.
His team found that type-III secretion systems and flagellae were important mechanisms for E. coli to adhere to and colonize the surface of spinach leaves. By experimentally mutating genes associated with the E. coli's flagellae, his team was able to show that this structure played a large role in adhering to and colonizing the surface of spinach leaves.
He is also exploring molecular mechanisms that may regulate the growth and organization of type-IV pili structures; if their genetic expression is tied to the expression of other virulence factors; and what role they may play in allowing E. coli O157:H7 to colonize human hosts. Dr. Girón is also interested in the combined interactions of how specific flagella of pathogenic E. coli interact with a host to create a cascade of signals which facilitate the agent’s attachment to epithelial and immune cells. He is also keeping an eye on the bigger picture of how the type-IV pili, flagella and specific protein secretions coordinate and regulate activities between pathogenic E. coli and their hosts. Dr. Girón has earned multiple grants from the NIH NIAID, Fresh Express Produce and the Arizona Disease Control Research Commission.
Applications for his research include preventing the occurrence of disease states by circumventing bacterial adherence (because adherence has to succeed before colonization can occur) through pili-based vaccines which could be administered domestic livestock, the bacteria's natural reservoir.
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