Project Summary/Abstract Influenza causes an estimated 1 billion cases yearly, with severe cases leading to fatal bronchopneumonia, particularly in vulnerable populations. Influenza virions express two major surface glycoproteins, hemagglutinin (HA) and neuraminidase (NA), the latter of which is of interest due to its role in viral egress and cleavage from mucus. Currently, the only FDA-approved antivirals used to treat influenza are neuraminidase inhibitors, which are ineffective against some strains. Monoclonal antibodies (mAbs) directed at NA provide an alternative therapeutic candidate. Delivering NA mAbs to the respiratory mucosal surface, where the virus replicates, is a novel delivery method that could improve drug efficacy and patient compliance. This five-year research career development award will provide training and development of the skills necessary for the candidate to establish an independent research laboratory focused on understanding how human antibodies against influenza can be harnessed to treat and prevent disease and transmission in animal models. Currently, the candidate is a veterinarian and a graduate trainee at the Vanderbilt Vaccine Center who will transition to an assistant professor position on the physician-scientist track in July 2024. Her training to date has focused on the isolation and characterization of human monoclonal antibodies (mAbs) from subjects with prior influenza history and mouse models of therapy. She will supplement this experience with further training in developing in vivo ferret and ex vivo human tissue models of influenza infection with which to study the natural pathogenesis of this virus and how human mAbs bind influenza to reduce pathogenesis. The short- term goals of the proposed studies are to test the central hypothesis that neuraminidase-directed antibodies play a significant role in the protective immune response and can be harnessed with antibody therapeutics. This training will be supported by mentoring from national experts in the study of human antibodies (James Crowe, Jr., Ivelin Georgiev), human airway epithelial cultures (Timothy Blackwell), influenza vaccinology (Spyros Kalams), and small animal models of virus infection and pathology (Katherine Gibson-Corley). The applicant aims to 1) elucidate the mechanisms of influenza type B (IBV) inhibition by mAbs specific to the neuraminidase (NA) glycoprotein to test the hypotheses that NA antibodies exert distinct mechanisms of protection, 2) use a human airway model of IBV infection to determine how NA mAbs in the presence of mucus behave, 3) and test these mAbs in a ferret model of intranasal delivery to test the hypothesis that NA mAbs delivered topically can reduce viral load and shedding. Overall, these studies will help define the role of IBV NA antibodies and the mechanism of delivering mAbs to the respiratory mucosal surface. Industry groups are developing protective mAbs made by the candidate as human therapeutic agents. Thus...