Ian Barclay Hogue, Ph.D - US grants

Project Summary/Abstract The alpha herpesviruses, which includes important human pathogen herpes simplex virus 1 (HSV-1), are among the very few viruses that have evolved neuron-specific viral mechanisms to exploit highly-specialized neuronal cell biology. During the natural course of disease, alpha herpesviruses infect sensory or autonomic neurons, and establish a life-long latent infection in the peripheral nervous system. Upon reactivation, the virus can return to peripheral tissues, causing herpetic or zosteriform lesions, or it can spread to the central nervous system, causing severe herpes encephalitis. This proposal focuses on three major steps in the HSV-1 replication cycle, where virus particles must interact with specialized neuronal systems: 1. long-distance post- entry axonal transport; 2. long-distance post-replication transport of progeny particles towards axonal sites of egress; 3. polarized viral egress via exocytosis from axons, dendrites, or cell bodies. In Aim 1, we will identify sites of HSV-1 particle exocytosis in neurons, and determine the molecular/cellular mechanisms of HSV-1 egress from axons, dendrites, or cell bodies. In Aim 2, we will investigate the structural biology of HSV-1 axonal transport by cryo electron microscopy (cryoEM). My prior education and research experience has focused on studying viruses from a molecular and cell biological perspective, in particular, studying the interactions of enveloped viruses with host membrane systems. In the course of my graduate and postdoctoral research, I have developed expertise in using specialized microscopy methods to spatiotemporally dissect particular steps in the virus replication cycle. In the current postdoctoral phase of my career, I have developed a novel live-cell fluorescence microscopy assay of virus egress based on a specialized fluorescence microscopy method and a novel pH-sensitive fluorescent probe. In addition, I am currently developing new cryoEM tomography methods to investigate axonal transport of virus particles. This proposal seeks to extend these methods to accomplish the proposed aims. My scientific background makes me well suited to carry out the proposed research. This K22 Career Transition Award will help me to achieve my scientific and career goals, which include transitioning to an independent position as an assistant professor, and establishing an independent NIH-funded research program focused on neurovirology.

Herpes Simplex Virus 1 (HSV-1), a member of the alpha herpesvirus subfamily, is among the very few viruses that naturally and productively exploit the mammalian nervous system, and, accordingly have evolved neuron- specific mechanisms to interact with highly-specialized neuronal cell biology. During the typical course of disease, alpha herpesviruses infect and establish latency in the peripheral nervous system (PNS). During lytic replication, such as following reactivation from latency, progeny virus particles spread back to peripheral tissues, causing recurrent herpetic lesions, and can also spread into the central nervous system (CNS). HSV-1 invasion of the CNS can cause severe and debilitating herpes encephalitis, or can be asymptomatic/sub- clinical. Once in the CNS, HSV-1 may trigger neuroinflammation and contribute to the development of neurodegenerative disease. To better understand the molecular and cellular mechanisms that underlie HSV-1 spread to the CNS, we propose an innovative method development/bioengineering goal: to develop methods to directly image virus particle exocytosis at or near neuronal synapses. This will involve culturing primary neurons on patterned substrates in order to induce synapse formation at defined locations and orientations. We will combine this method with our established live-cell virus exocytosis method to be able to image and study cell biological factors involved in viral exocytosis at or near synapses. Elucidating the basic cell biological processes that HSV-1 uses in neurons will increase our understanding of how and why herpesviruses spread in the nervous system, lead to the identification of druggable targets and development of better therapies for viral neuropathology, and may provide fundamental insights into the cell biology of neurons.