Comprehensively Defining the Novel Alphaviral Capsid Protein / IRAK1 Interaction - PROJECT SUMMARY / ABSTRACT Alphaviruses are mosquito-borne pathogens that are capable of causing significant outbreaks of severe clinical disease. Currently, for many alphaviruses there are no approved antiviral therapies, or safe and effective vaccines. Therefore, research which seeks to determine the mechanisms by which the alphaviruses evade or dysregulate the host innate immune response is essential and critically important to systematically defining alphaviral biology and the development of innovative antiviral strategies. The overarching research objective of this proposal is to comprehensively define the impact of a novel interaction between the alphaviral Capsid (CP) protein and the host IRAK1 protein. The rationale and scientific premises supporting this objective are based on the importance of the IRAK1 protein to host innate immune and inflammatory signaling pathways, and a robust body of preliminary evidence that indicates that the CP/IRAK1 interaction is highly conserved amongst the members of the genus Alphavirus, crucial to limiting the induction of type-I interferon, and essential to Sindbis (SINV) virus neuropathogenesis in vivo. Nonetheless, the precise impacts of the CP/IRAK1 interaction on alphaviral infection and pathogenesis remain fully unrealized, constituting a critical gap in the knowledgebase. Thus, we propose the following specific aims- i) To delineate the impact of the CP/IRAK1 interaction on alphaviral pathogenesis in vivo; ii) To define the molecular impacts of the CP/IRAK1 interaction on host cellular biology; and iii) to determine the impact and consequences of the CP/IRAK1 interaction on the alphaviral CP protein. Over the course of the first aim, we will utilize highly tractable mouse models of alphaviral infection and pathogenesis to specifically probe the role of the CP/IRAK1 interaction on the evasion of Toll-Like Receptor (TLR) signaling and induction of an innate immune response, and the dysregulation of IL-1 family cytokine signaling. The second aim uses robust cellular models to discern the mechanism by which the CP/IRAK1 interaction negatively impacts signaling and to define the precise impacts of the CP/IRAK1 interaction on the host response to IL-1 stimulation. Finally, the third aim uses robust cellular models of alphaviral infection to rigorously determine the molecular consequences of IRAK1-mediated phosphorylation of the CP protein. This proposed work is highly significant in that it will comprehensively assess the importance of the novel CP/IRAK1 interaction to alphaviral infection and pathogenesis. Moreover, these efforts are conceptually, and technically innovative as robust tried-and-true and state-of-the-art approaches, techniques, and models of infection will be used to rigorously define the biological and molecular importance of the CP/IRAK1 interaction. The successful completion of these efforts will serve to fundamentally expand the understanding of alphaviral biology and lay the foundation for the development of meaningful therapeutic interventions.
