DMID 23-0015; Lassa Fever CVD 1000

Lassa fever is a zoonotic infection endemic in West Africa and is spread by the Lassa virus, an arenavirus causing hemorrhagic fever. Up to 300,000 Lassa fever infections occur annually and while disease is often mild, in a subset of individuals disease is characterized by severe anemia, bleeding, encephalopathy, respiratory failure, shock, and high mortality. In some regions of West Africa, up to 15% of hospital admissions are secondary to Lassa fever, and an estimated 5,000 deaths occur annually. During epidemics of disease, case-fatality rates may reach as high as 50% in hospitalized patients. Approximately one-third of infected individuals will develop hearing loss regardless of disease severity, and in a proportion of patients, permanent deafness occurs. Prevention of illness through vaccination is a critical goal in reducing the burden of disease from Lassa fever. There are currently no vaccines or therapeutics demonstrated to be efficacious in the prevention or treatment of Lassa fever. This study proposes the evaluation of a novel, first-in-human Lassa fever vaccine based on the complete Lassa glycoprotein complex (GPC) antigen. The antigen will be presented on a genetically modified and attenuated rabies vector expressing both the rabies glycoprotein (GP) antigen and the Lassa GPC. The inactivated chimeric virus is delivered with a toll-like receptor (TLR-4)-activating oil-in-water emulsion adjuvant. Studies using this vaccine administered as a prime-boost series in mice and non-human primates, and then challenged with Lassa virus demonstrated significant protection against Lassa fever. Given that the vaccine backbone is an attenuated and inactivated rabies virus expressing rabies GP, this vaccine will also be evaluated for immunogenicity against rabies virus.