**5. Conclusions**

In conclusion, our data indicate that CedV F protein is indeed internalized from the cell surface as described for HeV and NiV F proteins. Furthermore, endocytic uptake of CedV F protein is signal-mediated and represents a key step in order to gain biological activity. Future studies should investigate proteolytic activation in more detail in order to find further commonalities and/or di fferences in subcellular localization and protease usage between high and low pathogenic henipaviruses. Further, tyrosine-based motifs should be analyzed for their e ffects on sorting and endocytic tra fficking of the CedV F protein including their ability to influence virus particle assembly and their potential e ffect on virus-cell fusion/infectivity.

**Supplementary Materials:** The following are available online at http://www.mdpi.com/2073-4409/9/9/2054/s1, Figure S1: Proteolytic processing of CedV F wt and mutants e8 (e3 + e4) and e9 (e3 + e5), Figure S2: Proteolytic processing of CedV F protein is inhibited by chlorpromazine, Figure S3: Co-expression of CedV F wt, mutants and CedV G protein on the cell surface.

**Author Contributions:** Conceptualization, K.F. and S.D.; methodology and investigation, K.F.; analysis: K.F. and S.D.; supervision: S.D.; funding acquisition, S.D.; resources, M.H.G.; writing, K.F. and S.D. All authors have read and agreed to the published version of the manuscript.

**Funding:** Funding was provided by the Friedrich-Loeffler-Institut, intramural funding (S.D.) and funding as part of the VISION consortium (K.F.).

**Acknowledgments:** The authors wish to thank Stefanie Rößler and Carolin Rüdiger for excellent technical support and Thomas Hoenen for helpful comments and critical reading of this manuscript. The authors further acknowledge Angela Römer-Oberdörfer (pCITE) and Thomas Hoenen (pCAGGS T7) for providing the aforementioned plasmids used in this study. Many thanks to Bärbel Hammerschmidt and the animal keepers for help with the generation of polyclonal CedV F-specific serum and to Christine Luttermann for sequencing of mutants.

**Conflicts of Interest:** The authors declare no conflict of interest.
