Title:

Development of Novel Anti-Respiratory Syncytial Virus Therapies

Issue Date: Jun-2017
Abstract (summary): Respiratory syncytial virus (RSV) is a leading cause of mortality in infants and young children. Despite the RSV disease burden, no vaccine is available and treatment remains non-specific. New drug candidates are needed to combat RSV. Towards this goal, we investigated two broad strategies to control RSV infection. First, we examined the utility of delivering an anti-4-1BB agonist antibody to enhance CD8 T cell costimulation in a mouse model of RSV infection. This strategy enhanced CD8 T cell numbers, however failed to reduce RSV titers in the lung. We found that this was likely due to reduced RSV specific CD8 T cells in the lung. Overall, this strategy did not attenuate RSV associated disease outcomes and was associated with increased morbidity. Second, we screened over 2000 FDA approved compounds to identify approved drugs with novel anti-RSV activity. Cardiac glycosides, inhibitors of the membrane bound Na+/K+-ATPase, were identified to have anti-RSV activity. Cardiac glycosides diminished RSV infection in HEp-2 cells and in primary human airway epithelial cells grown at an air liquid interface. Digoxin, an FDA approved cardiac glycoside, was further able to inhibit RSV infection of community isolates of RSV in primary nasal epithelial cells. Our results suggest that the antiviral effects of cardiac glycosides are primarily dependent on changes in the intracellular Na+ and K+ composition. Consistent with this mechanism, we subsequently demonstrated that the ionophoric antibiotics salinomycin, valinomycin, and monensin inhibited RSV in HEp-2 cells and primary nasal epithelial cells. Our data indicate that the K+/Na+ sensitive steps in the RSV lifecycle occur within the initial 4 hours of virus infection, but do not include virus binding/entry. We employed an RSV mini-replicon assay allowing the independent assessment of RSV-specific RNA synthesis. Our findings demonstrated that digoxin does not alter the RSV RNA polymerase. Future studies will focus on the possibility that digoxin and other ion-modulating drugs may impact viral uncoating (i.e. release of viral nucleic acid from RNP complex).
Content Type: Thesis

Permanent link

https://hdl.handle.net/1807/79410

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