Wednesday, June 4, 2025
6/4/2025
Defining how ubiquitination of Ebola viral proteins affect host-viral dynamics - PROJECT SUMMARY / ABSTRACT Ebola virus (EBOV), part of the Filoviridae family, causes periodic outbreaks of severe hemorrhagic fever and Ebola virus disease, with case fatality rates as high as 90%. These are highly virulent and emerging zoonotic pathogens, thus a significant threat to human health, potential agents of bioterrorism, and NIAID category A priority pathogens. While a set of EVD clinical symptoms have been defined, the molecular mechanisms that drive EBOV pathogenesis remain poorly understood. Despite current development of a vaccine, anti-filovirus prophylactics and therapeutics are very limited, in part due to the paucity of information on host and viral interactions. EBOV encodes for multifunctional proteins, including VP35. VP35 is a polymerase co-factor necessary for both viral replication and transcription and serves as the main innate immune antagonist. Currently, there is a major gap in our understanding of the role host factors play at critical stages in the viral replication cycle. Our group recently conducted interactome screens for various EBOV proteins to identify key host-viral interactions, which identified a novel interaction between a RING-type E3 ubiquitin ligase and Ebola VP35. In the work proposed here, I will use biochemical and structural biology tools to define the impact of ubiquitination on VP35 function (Aim 1). In Aim 2, I will assess the impact of VP35 on the host ubiquitination machinery, with a specific focus on type I interferon response. Ubiquitination serves powerful regulatory roles in eukaryotes, and there is increasing evidence that viruses can antagonize the immune response by interfering with host ubiquitin- dependent pathways, or by hijacking the host ubiquitination machinery to promote viral pathogenesis. Prior literature and my preliminary data indicate that EBOV proteins interact with the host ubiquitination machinery. I expect my proposed work on VP35 to determine the molecular mechanism of how this interaction impacts host- viral dynamics. This work will also provide an experimental framework to define mechanisms by which other viral proteins interact with the host ubiquitin machinery. My long-term career goal is to establish myself as a physician scientist with expertise to address questions about mechanisms that drive microbial pathogenesis, and use this knowledge to improve patient care. With the proposed studies, I will work towards this goal by uncovering and characterizing macromolecular interactions at the host-pathogen interface. I will also enhance my experimental skills, advance my scientific communication, and expand my teaching and mentorship skills. To accomplish this, I have designed a training plan with an interdisciplinary team of mentors, including my sponsor Dr. Gaya Amarasinghe with a track record of using biochemical and structural biology approaches to define key mechanisms in viral pathogenesis. On my advising committee I also have a biochemist with expertise in post- translational modifications (Dr. Natalie Neimi), an innate immunologist (Dr. Deborah Lenschow), a virologist and cell biologist (Dr. Siyuan Ding), and the chair of my committee is Dr. Jennifer Philips, an infectious disease physician scientist who will lend her expertise in host-pathogen biology as well as career guidance.
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