The long-term goal of this laboratory is to understand the mechanism of infection by enveloped viruses. Previously, we have identified receptors for several retroviruses and investigated how these proteins activate the virus entry machinery. Recently, we discovered that endosomal cysteine proteases are essential host factors for Ebola virus infection. The roles of these proteases in spread and pathogenesis of Ebola and other hemorrhagic fever viruses are now being investigated. Also, specific inhibitors of these proteases are being developed as anti-Ebola virus drugs.