Expression of Ebolavirus glycoprotein on the target cells enhances viral entry

BACKGROUND: Entry of Ebolavirus to the target cells is mediated by the viral glycoprotein GP. The native GP exists as a homotrimer on the virions and contains two subunits, a surface subunit (GP1) that is involved in receptor binding and a transmembrane subunit (GP2) that mediates the virus-host membrane fusion. Previously we showed that over-expression of GP on the target cells blocks GP-mediated viral entry, which is mostly likely due to receptor interference by GP1. RESULTS: In this study, using a tetracycline inducible system, we report that low levels of GP expression on the target cells, instead of interfering, specifically enhance GP mediated viral entry. Detailed mapping analysis strongly suggests that the fusion subunit GP2 is primarily responsible for this novel phenomenon, here referred to as trans enhancement. CONCLUSION: Our data suggests that GP2 mediated trans enhancement of virus fusion occurs via a mechanism analogous to eukaryotic membrane fusion processes involving specific trans oligomerization and cooperative interaction of fusion mediators. These findings have important implications in our current understanding of virus entry and superinfection interference.