Mechanisms of Neuronal Infection by Prototype Emerging Bunyaviruses

PROJECT SUMMARY/ABSTRACT Bunyaviruses are a diverse group of animal and human pathogens of global health relevance. Bunyavirales order encompasses viral families with similar genome and protein organization despite divergent sequences. Common to these vector-borne viruses is the ability to cause central nervous system (CNS) disease with concomitant morbidity and occasional mortality. Lack of definition of key target cells in the brain and the effect of virus infection on the brain microenvironment are major limitations in our knowledge of bunyavirus neuropathogenesis that has also limited our ability to develop countermeasures. The consequences of target cell infection are unknown, and viral determinants of neurologic disease have not been delineated. To overcome this limitation, we propose a comparative analysis of the neuropathogenesis of 3 medically important prototype emerging bunyaviruses and define contributors to infection and pathogenesis in relevant neuronal cells. La Crosse virus (LACV) is found in North America and is the primary cause of pediatric viral encephalitis in the United States. Rift Valley Fever virus (RVFV), a WHO Priority Disease, causes outbreaks of hemorrhagic fever and encephalitis throughout Africa. Oropouche virus (OROV), is found in South America and has caused more than 30 large epidemics resulting in over 500,000 human cases of febrile illness. Due lack of direct comparisons, substantial gaps remain in our understanding of bunyavirus neuropathogenesis, including molecular mechanisms. This proposal will provide comparative analysis of all 3 viruses with regards to CNS cell tropism, innate immune responses, and cell death pathways using novel in vitro and ex vivo model systems. Our recently published data shows that the host cell protein LDL-receptor related protein 1 (Lrp1) is important for efficient cellular infection by RVFV and OROV. Preliminary data on the role of Lrp1 in LACV infection further supports similar tropisms by divergent viruses. We hypothesize that these neurovirulent viruses share overlapping target cells in the CNS mediated by the host cell protein Lrp1. Viral non-structural protein produced from the small genome segment (NSs) functions as the main antagonist of host cell antiviral responses and a key modulator during infection. We further hypothesize that the degree of neurovirulence of each virus is related to NSs protein function. Our highly collaborative and synergistic team is led by Dr. Amy Hartman (PI), an expert in the pathogenesis of RVFV and Dr. Gaya Amarasinghe (Co-I), a biochemist with expertise in host-pathogen interactions. Two additional Co-I's are Dr. Leonard D'Aiuto and Dr. Zachary Wills, are experts in viral infection of human neurons and rodent neurobiology, respectively. This R01 proposal represents a multidisciplinary approach to advance our understanding of bunyavirus interactions with neurons.