e Outbreaks of emerging infections present health professionals with the unique challenge of trying to select appropriate pharmacologic treatments in the clinic with little time available for drug testing and development. Typically, clinicians are left with general supportive care and often untested convalescent-phase plasma as available treatment options. Repurposing of approved pharmaceutical drugs for new indications presents an attractive alternative to clinicians, researchers, public health agencies, drug developers, and funding agencies. Given the development times and manufacturing requirements for new products, repurposing of existing drugs is likely the only solution for outbreaks due to emerging viruses. In the studies described here, a library of 290 compounds was screened for antiviral activity against Middle East respiratory syndrome coronavirus (MERS-CoV) and severe acute respiratory syndrome coronavirus (SARS-CoV). Selection of compounds for inclusion in the library was dependent on current or previous FDA approval or advanced clinical development. Some drugs that had a well-defined cellular pathway as target were included. In total, 27 compounds with activity against both MERS-CoV and SARS-CoV were identified. The compounds belong to 13 different classes of pharmaceuticals, including inhibitors of estrogen receptors used for cancer treatment and inhibitors of dopamine receptor used as antipsychotics. The drugs identified in these screens provide new targets for in vivo studies as well as incorporation into ongoing clinical studies.

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The VP40 matrix protein of Ebola virus buds from cells in the form of virus-like particles (VLPs) and plays a central role in virus assembly and budding. In this study, we utilized a functional budding assay and cotransfection experiments to examine the contributions of the glycoprotein (GP), nucleoprotein (NP), and VP24 of Ebola virus in facilitating release of VP40 VLPs. We demonstrate that VP24 alone does not affect VP40 VLP release, whereas NP and GP enhance release of VP40 VLPs, individually and to a greater degree in concert. We demonstrate further the following: (i) VP40 L domains are not required for GP-mediated enhancement of budding; (ii) the membrane-bound form of GP is necessary for enhancement of VP40 VLP release; (iii) NP appears to physically interact with VP40 as judged by detection of NP in VP40-containing VLPs; and (iv) the C-terminal 50 amino acids of NP may be important for interacting with and enhancing release of VP40 VLPs. These findings provide a more complete understanding of the role of VP40 and additional Ebola virus proteins during budding.Ebola virus is a member of the Filoviridae family and is associated with recurrent outbreaks of deadly hemorrhagic fevers (8). Currently, there are no approved vaccines, nor are there antiviral therapeutics to prevent or treat individuals infected with Ebola virus (16). A better understanding of the molecular aspects of Ebola virus replication will be necessary for successful development of specific treatments for Ebola virus infection.The VP40 matrix protein of Ebola virus is the most abundant virion protein and plays a key role in virus assembly and budding (12,14,28). For example, VP40 can bud as a filamentous virus-like particle (VLP) from mammalian cells in the absence of any other viral protein (12,20). The ability of VP40 to bud as a VLP is due, in part, to the presence of L domains present at the N terminus of the protein (12,14,17). Viral L domains are thought to serve as docking sites for interactions with specific cellular proteins, and the resultant virus-host interactions are believed to facilitate efficient virus budding (for a review, see reference 9). Although VP40 and other viral matrix proteins (e.g., Gag and M proteins of retroviruses and rhabdoviruses, respectively) can bud independently from cells, additional viral proteins are undoubtedly important for the budding process. For example, the G protein of vesicular stomatitis virus (VSV) has been shown to be important for efficient budding. More specifically, the membrane-proximal stem, transmembrane domain, and cytoplasmic tail of VSV G appear to confer this efficiency (21, 25). In addition, alterations to the cytoplasmic tails of glycoproteins of other RNA viruses, such as influenza A, simian virus 5, and rabies virus, appear to result in poor budding despite an intact matrix protein (15,19,23).In addition to VP40, the surface glycoprotein (GP), the nucleoprotein (NP), and the minor matrix protein (VP24) of Ebola virus have been implicated in virus assembly and budding (1,11,12)...