Bacteria and Lymphocyte Suppression in Periodontitis

We are requesting a one year administrative supplement to our RO1 grant DE006014 entitled Bacteria and lymphocyte suppression in periodontitis. The purpose of this request is to expand the scope of the grant to take advantage of recent observations made on the cytolethal distending toxin (Cdt) and apply them to advancing our knowledge of and identifying novel therapeutic pathways for preventing SARS-CoV-2 infection. Specifically, we have identified a novel role for a host cell protein, cellugyrin (synaptogyrin-2; discussed below), which plays a requisite role in the internalization and endososmal trafficking of the active subunit of Cdt, CdtB; these events are critical to toxicity. Like the internalization process utilized by exotoxins, viruses must gain entry into host cells; this process involves the interaction between viral glycoprotein, such as SARS-CoV-2 spike protein. This protein, like other viral spike proteins, provides a receptor binding domain that confers host cell specificity (e.g, ACE2) and also fusogenic function critical to merging the virus envelope with host endosomal membrane during viral entry. Recent studies have indicated that oral epithelial cells express ACE2 and may be a target for SARS- CoV-2 infection. Therefore, this study will focus on human oral-pulmonary epithelial cells lines. We propose that cellugyrin is a major component of a universal endocytic process utilized by both virus and exotoxins to achieve entry into host cells. This study will focus on the requirement for cellugyrin for SARS-CoV-2 entry into host cells. In order to contain SARS-CoV-2 infection, it is important to identify early molecular mechanism(s) that contribute to its high infectivity as these likely also represent attractive targets for therapeutic intervention. This proof-of-principle study is aimed at demonstrating a key role for cellugyrin in the pathogenesis of SARS-CoV-2 infection of cells within the oral-respiratory tract. The potential for high impact of these studies is to provide the underpinnings for developing a novel, alternative and potentially transformative therapeutic approach to mitigate SARS-CoV-2 infection. It is in this context that this study directly addresses the spirit and focus of the Notice of Special Interest (NOSI) (NOT-DE-20-022): Urgent Competitive Revisions and Administrative Supplements for Coronavirus Disease 2019 (COVID-19) as it is not only of potential high impact, but also addresses acquisition of a more robust understanding of SARS-CoV-2 pathogenesis. Moreover, the proposal addresses one of the bulleted targets of this funding announcement: examination of the role of oral/nasal microbiota and ACE2 receptor on SARS-CoV-2 infectivity and carriage in oral fluids and nasal secretions, as gateways to the spreadof infection into the respiratory tract via proof of principle studies.