EGF as an environmental cue of B. burgdorferi gene regulation

/ABSTRACT Lyme disease is the most common vector borne disease in the northern hemisphere, causing nearly 500,000 cases in the United States alone each year. This disease is caused by the spirochete Borrelia burgdorferi, which is transmitted to humans by the bite of an infected Ixodes tick. To persistently infect a host, B. burgdorferi must transmit from a tick, colonize the initial site of infection, and disseminate to distal tissues. Each stage of the infection cycle provides different environmental pressures, so the spirochetes undergo stage-specific transcriptional regulation to express genes required for their survival. I have recently discovered that epidermal growth factor (EGF) may be an environmental cue recognized by B. burgdorferi to coordinate this stage-specific gene expression. In my preliminary data, EGF directly bound to the spirochetes and induced a B. burgdorferi transcriptomic profile consistent with what is seen at later stages of infection. This is the first description of B. burgdorferi directly binding to a host protein to coordinate gene expression. However, the binding of EGF to B. burgdorferi and the resulting transcriptional regulation remains poorly characterized. Here, I aim to characterize binding by estimating the binding kinetics and specificity with flow cytometry and surface plasmon resonance, and by determining the spatial dynamics with immunofluorescence and electron microscopy. Further, I aim to dissect EGF-mediated transcriptional regulation by comprehensively characterizing the B. burgdorferi transcriptome following EGF treatment, and by identifying responsible transcription factors through the use of transcription factor knockout B. burgdorferi strains. Overall, the work proposed here will immediately expand our understanding of B. burgdorferi host sensing, identify a vulnerable interaction, and establish an exciting new paradigm by which the direct binding of a host protein impacts the coordination of B. burgdorferi gene expression. Further, it will lay the foundation for future studies to increase our understanding of Lyme disease pathogenesis, and result in powerful new treatments and therapeutics to limit the public health burden of this disease. Under this K22 award I will work with my mentors and collaborators to develop the expertise needed to successfully execute the bacterial transcriptomic and imaging studies detailed here. Further, I will attend career development workshops and work with my mentors to develop the skills needed to build my own grant-funded research program at a leading academic institution. Overall, this proposed K22 award will provide me with the time and structure needed to train and develop professionally so that I may meet my career goal of becoming an independent investigator focusing on host-pathogen interactions shaping vector borne disease pathogenesis. Project Number: 1K22AI184753-01 | Fiscal Year: 2025 | NIH Institute/Center: National Institute of Allergy and Infectious Diseases (NIAID) | Principal Investigator: Thomas Hart | Institution: JOHNS HOPKINS UNIVERSITY, BALTIMORE, MD | Award Amount: $162,000 | Activity Code: K22 | Study Section: Microbiology and Infectious Diseases Research Study Section[MID] View on NIH RePORTER: https://reporter.nih.gov/project-details/1K22AI18475301