Tetraspanin CD81 restricts Ebola virus infection and is antagonized by glycoprotein GP and matrix protein VP40

Viruses manipulate host cell membranes to evade antiviral immunity, prevent superinfection, and optimize their replication and spread. The Ebola virus glycoprotein GP mediates viral entry but also contributes to the subversion of host antiviral immune responses. Here, we characterize the impact of Ebola virus GP on cell surface proteins and show that it reduces cell surface availability of tetraspanins CD81, CD63, and CD9. This function is conserved among several filoviral glycoproteins but not observed for glycoproteins of other viral families. Whereas CD63 and CD9 are largely dispensable for Ebola virus replication, CD81 suppresses virus-like particle entry and viral replication. This activity might be attributed to CD81-mediated suppression of NF-κB signaling, which is induced by the Ebola virus matrix protein VP40 and transcription- and replication-competent virus-like particle (trVLP) replication. Our results further indicate that both GP, which interacts directly with CD81, and VP40, which also associates with CD81, function to reduce total and surface expression levels of CD81. CD81 is shown to reduce levels of Ebola virus RNA species, and its antibody-mediated clustering can suppress Ebola virus infection. Our study provides insights into the roles of NF-κB signaling in Ebola virus replication and immunopathogenesis, and identifies tetraspanin CD81 as a potentially druggable Ebola virus-inhibitory host factor.