Characterization of an influenza virus pseudotyped with Ebolavirus glycoprotein
Xiao J., Rijal P., Schimanski L., Tharkeshwar AK., Wright E., Annaert W., Townsend A.
<jats:p>We have produced a new Ebola virus pseudotype: E-S-FLU, which can be handled in biosafety level-1/2 containment for laboratory analysis. E-S-FLU is a single cycle influenza virus coated with Ebolavirus glycoprotein, and it encodes enhanced green fluorescence protein as a reporter that replaces the influenza haemagglutinin. MDCK-SIAT1 cells were transduced to express Ebolavirus glycoprotein as a stable transmembrane protein for E-S-FLU production. Infection of cells by E-S-FLU was dependent on Niemann-Pick C1 protein, which is the well-characterized receptor for Ebola virus entry at the late endosome/lysosome membrane. E-S-FLU was neutralized specifically by anti-Ebola glycoprotein antibody and a variety of small drug molecules that are known to inhibit entry of wild-type Ebola virus. To demonstrate the application of this new Ebola virus pseudotype, we show that a single laboratory batch was sufficient to screen a library (LOPAC®1280 Sigma) of 1280 pharmacologically active compounds for inhibition of virus entry. 215 compounds inhibited E-S-FLU infection, while only 22 inhibited the control H5-S-FLU virus coated in an H5 haemagglutinin. These inhibitory compounds have very dispersed targets and mechanisms of action e.g. calcium channel blockers, estrogen receptor antagonists, anti-histamines, serotonin uptake inhibitors etc. and this correlates with inhibitor screening results with other pseudotypes or wild-type Ebola virus in the literature. E-S-FLU is a new tool for Ebola virus cell entry studies and is easily applied to high throughput screening assays for small molecule inhibitors or antibodies.</jats:p><jats:p><jats:bold>Importance</jats:bold>Ebola virus is from the<jats:italic>Filoviridae</jats:italic>family and is a biosafety level 4 pathogen. There are no FDA-approved therapeutics for Ebola virus. These characteristics warrant the development of surrogates of Ebola virus that can be handled in more convenient laboratory containment to study the biology of the virus, and screen for inhibitors. Here we characterized a new surrogate named E-S-FLU, that is based on a disabled influenza virus core coated with the Ebola virus surface protein, but does not contain any genetic information from the Ebola virus itself. We show that E-S-FLU uses the same cell entry pathway as wild-type Ebola virus. As an example of the ease of use of E-S-FLU in biosafety level-1/2 containment, we showed that a single production batch could provide enough surrogate virus to screen a standard small molecule library of 1280 candidates for inhibitors of viral entry.</jats:p>