Protection of Ferrets Against Avian Influenza H7N9 Challenge Following Intranasal Dosing of Inert Bacterial Spores

Abstract

Background Influenza is a respiratory infection that continues to present a major threat to human health with ~ 500,000 deaths/year. Continued circulation of epidemic subtypes in humans and animals potentially increases the risk of future pandemics. Vaccination has failed to halt the evolution of this virus and additional "universal" prophylactic approaches should be considered. Naked, "heat inactivated", or inert, bacterial spores have been shown to protect against influenza in murine models. Methods Ferrets were administered intranasal doses of inert bacterial spores (DSM 32444K). Seven days after the last dose animals were challenged with H7N9. Clinical signs of infection and viral shedding were monitored. Results Clinical symptoms of infection were significantly reduced in animals dosed with DSM 32444K. The temporal kinetics of viral shedding were reduced but not abolished, Conclusion Taken together nasal dosing using heat-stable spores could provide a simple, cost-effective approach for influenza prophylaxis in both humans and animals.