Identification of Ebola Virus Entry Inhibitors

DESCRIPTION (provided by applicant): Ebola virus (EBOV) causes periodic outbreaks of severe viral hemorrhagic fevers in Africa with high mortality rates in infected patients. EBOV can be used in acts of bio-terrorism because of its highly infectious nature and stability in aerosolized form. It is classified as a Category A bioweapons agent by the Centers for Disease Control and Prevention (CDC). Currently, there is no FDA approved vaccine or antiviral drug that is effective against EBOV infections in humans. However, vaccines will only be partially effective in controlling an EBOV outbreak or bioterrorist attack since rapid progression of EBOV infection offers little opportunity for developing acquired immunity. Therefore, there is a critical need for to respond to postexposure or bioterrorist attack. EBOV infection is initiated by the fusion between viral and host cell membranes, which is mediated by the viral membrane glycoprotein (GP). This selective interaction between EBOV GP and host cell surface receptor molecules is essential for the initiation and establishment of the infection. Therefore, blocking of EBOV entry into its target cell will be advantageous since this will lead to suppression of viral infectivity early in its life cycle. Our objective is to discover and develop small molecule entry inhibitors against EBOV infection. Considering the aggressive nature of EBOV infection, and its extreme virulence, biosafety level 4 containment facilities are required to study the virus. To circumvent these stringent biohazard conditions, we will generate EBOV pseudotype virus as surrogate model to study EBOV attachment/entry. This model system allows the study of viral entry into the cell without replicating other aspects of the viral life cycle and therefore can be performed in a biosafety level 2 facility. In Phase I, we will develop a high-throughput screening (HTS) assay utilizing the EBOV pseudotype virus to measure virus infection. This assay will be used to screen libraries of structurally diverse small molecules in "Microbiotix Inc's" repository, to identify potent inhibitors of EBOV entry. Inhibitors will be further confirmed for antiviral activity in a secondary EBOV pseudotype virus plaque assay, and infectious EBOV plaque assay. They will also be assessed for mammalian cytotoxicity. In Phase II, we will progress the most promising scaffolds through a rational drug design program, and lead compounds will be tested for efficacy and toxicity in animal models. The most active compound, with the least toxicity, will advance to IND enabling studies (Phase III). Therefore the specific aims of this Phase I application are to: 1. Develop a high-throughput screening (HTS) assay for selecting inhibitors of EBOV attachment/entry; 2. Screen a diverse compound library "Microbiotix Inc."s repository to identify and confirm selective inhibitors of EBOV; 3. EBOV inhibitor confirmation; and 4. Prioritize screening hits based on spectrum, cytotoxicity and mechanism. The end result of Phase 1 work will be identification of hits specific for EBOV entry inhibition.