Inhibitors of Ebola Virus Infection

Ebola virus (EboV) is readily transmitted and rapidly fatal, and there is no effective vaccine or drug therapy. Recent experiments reveal that the physiological trigger for EboV infection is stepwise proteolytic cleavage of the envelope glycoprotein (GP) by cathepsin L and cathepsin B, two members of a family of endosomal cysteine proteases. Importantly, well-characterized small molecule inhibitors of cathepsin proteases markedly inhibit EboV infection in vitro (>99%). The goal of this proposal is to develop the potential of cathepsin inhibitors as anti-EboV drugs.

Specific Aim 1: Develop pipeline of small molecules that inhibit EboV GP-dependent infection.  Major classes of cathepsin inhibitors will be screened to identify lead compounds with anti-EboV activity, including inhibitors already under development for other disorders. In addition, specific inhibitors of EboV-GP infection identified in an earlier high-throughput screen will be characterized for ability to inhibit cathepsin activity or to act synergistically with known cathepsin inhibitors. The anti-EboV activity of promising lead compounds will be assessed in existing animal models.

Specific Aim 2: Determine role of cathepsins in EboV infection. Selective inhibitors and knockout-derived cell lines will be used to identify all cathepsins that mediate EboV and Marburg virus infection.  This project will also identify the cathepsins that mediate infection of host tissues where EboV replication is high, and develop a BL3-based system to select and analyze EboV variants that are dependent on specific cathepsins and/or are resistant to specific inhibitors.

Specific Aim 3: Design, synthesize and test second generation EboV inhibitors as part of a drug development plan. Specific aims 1 and 2 will inform the starting point for an iterative lead optimization protocol to identify the most highly selective cathepsin inhibitors that retain potent and broad anti-EboV activity.