Dissecting host-virus interactions underlying motor neuron toxicity in Acute Flaccid Myelitis

Project Summary Acute flaccid myelitis (AFM) is a debilitating polio-like paralytic illness of children caused by enterovirus infection. There have been several international outbreaks of AFM in the past decade associated with Enterovirus D68 (EV-D68) and Enterovirus A71 (EV-A71), representing a significant public health threat. AFM is characterized by viral invasion of the spinal cord with subsequent infection of motor neurons followed by their dysfunction and death, however the mechanisms leading to motor neuron injury are not known. Interestingly, EV-A71 is associated with a spontaneously reversible form of AFM, whereas the paralysis resulting from EV-D68 infection is typically permanent. We will therefore leverage this clinical observation to identify which EV-D68 gene or genes are responsible for irreversible paralysis via motor neuron toxicity, and identify perturbed host neuronal functions that lead to cell death. We hypothesize that the EV-D68 2A protease (2Apro) promotes the death in motor neurons via mechanisms that include NPC dysfunction and Wallerian degeneration, and that these processes are effective targets for therapeutic intervention. Our preliminary data in induced pluripotent stem cell (iPSC)-derived motor neurons show increased toxicity of EV-D68 vs EV-A71 and demonstrate evidence of nuclear pore complex (NPC) dysfunction and Wallerian degeneration in EV-D68- infected neurons. Our first aim is to identify viral factors causing differential motor neuron toxicity of Enterovirus D68 vs Enterovirus A71. Our second aim is to determine the extent of persistent Nuclear Pore Complex dysfunction in motor neurons after EV-D68 infection and evaluate approaches for Nuclear Pore Complex repair. Our third aim is to define the role of Wallerian degeneration in EV-D68-induced motor neuron dysfunction and death. We will achieve these aims via complementary in vitro and in vivo approaches using human iPSC-derived motor neurons, and a well-established mouse model of AFM via intramuscular injection of enteroviruses. At the conclusion of the study, we will also identify strategies for NPC repair and novel regulatory pathways of NPC biogenesis, reveal a role for Wallerian degeneration in neuroinfectious disease, and establish a rationale for neuroprotective therapies in AFM.