Analysis of Ebola entry and development of the entry inhibitors

Ebola virus infection causes severe hemorrhagic fever in human and non-human primates with high mortality rate up to 90%. Currently there are no vaccines or therapy available for human use. Entry is the first step of virus infection and is an ideal target for anti-viral therapy. Ebola entry is mediated by its glycoprotein (GP). Using an human immunodeficiency virus (HIV)-based pseudotyping system, function of Ebola GP residues in viral entry was studied extensively by mutagenesis. The role of these mutated residues in protein expression/folding was examined by biochemical methods. Our results showed that the receptor-binding domain (RBD) is located at the N-terminal 150 residues of Ebola GP and many residues play an important role in GP structure/function. Both entry interference assay and protein binding assay suggested that R64 and K95 interact with the receptor/cell directly. Our results also suggested that Ebola and Marburg viruses share a common cellular molecule for entry. Furthermore, using the pseudotyping system, a small molecule compound (C-37) was identified to inhibit viral entry mediated by Ebola and Marburg GP. In order to improve the anti-Ebola efficacy, 55 derivatives of the compound were synthesized and some of them could inhibit Ebola entry more efficiently. These findings contribute to our understanding of Ebola entry mechanism and development of Ebola entry inhibitors.