Besides its function in transcription and replication, MARV VP35 acts as an IFN antagonist. While the impact of EBOV VP35 on the host's antiviral response has been intensively investigated (reviewed in [129] ), much less information is available about similar functions of MARV VP35. When we tested MARV VP35 for its ability to block IFN induction in a reporter gene assay, it blocked reporter gene expression as efficiently as EBOV VP35 (unpublished data). In addition, Bosio and colleagues [146] reported that expression of MARV VP35 in the absence of other viral proteins was sufficient to completely block the induction of IFNα in stimulated human dendritic cells. Besides its ability to inhibit the induction of Type I IFN, EBOV VP35 has been shown to block the activation of the antiviral protein PKR and to interfere with RNA silencing pathways. Importantly, EBOV VP35 is a dsRNA binding protein. The C-terminus of EBOV VP35 contains a domain with patches of basic amino acids which is important for dsRNA binding and the protein's inhibitory functions (for review see [129] ). This C-terminal region, the so-called IFN inhibitory domain, is conserved in MARV VP35 [147] , suggesting that MARV VP35 possesses similar inhibitory functions.