Ebola virus requires a host scramblase for externalization of phosphatidylserine on the surface of viral particles

PLoS Pathog. 2018 Jan 16;14(1):e1006848. doi: 10.1371/journal.ppat.1006848. eCollection 2018 Jan.


Cell surface receptors for phosphatidylserine contribute to the entry of Ebola virus (EBOV) particles, indicating that the presence of phosphatidylserine in the envelope of EBOV is important for the internalization of EBOV particles. Phosphatidylserine is typically distributed in the inner layer of the plasma membrane in normal cells. Progeny virions bud from the plasma membrane of infected cells, suggesting that phosphatidylserine is likely flipped to the outer leaflet of the plasma membrane in infected cells for EBOV virions to acquire it. Currently, the intracellular dynamics of phosphatidylserine during EBOV infection are poorly understood. Here, we explored the role of XK-related protein (Xkr) 8, which is a scramblase responsible for exposure of phosphatidylserine in the plasma membrane of apoptotic cells, to understand its significance in phosphatidylserine-dependent entry of EBOV. We found that Xkr8 and transiently expressed EBOV glycoprotein GP often co-localized in intracellular vesicles and the plasma membrane. We also found that co-expression of GP and viral major matrix protein VP40 promoted incorporation of Xkr8 into ebolavirus-like particles (VLPs) and exposure of phosphatidylserine on their surface, although only a limited amount of phosphatidylserine was exposed on the surface of the cells expressing GP and/or VP40. Downregulating Xkr8 or blocking caspase-mediated Xkr8 activation did not affect VLP production, but they reduced the amount of phosphatidylserine on the VLPs and their uptake in recipient cells. Taken together, our findings indicate that Xkr8 is trafficked to budding sites via GP-containing vesicles, is incorporated into VLPs, and then promote the entry of the released EBOV to cells in a phosphatidylserine-dependent manner.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Chlorocebus aethiops
  • Ebolavirus / physiology*
  • HEK293 Cells
  • Hemorrhagic Fever, Ebola / metabolism
  • Hemorrhagic Fever, Ebola / virology
  • Host-Pathogen Interactions*
  • Humans
  • Phosphatidylserines / metabolism*
  • Phospholipid Transfer Proteins / physiology*
  • Vero Cells
  • Viral Core Proteins / metabolism
  • Virion / metabolism*
  • Virus Release


  • Phosphatidylserines
  • Phospholipid Transfer Proteins
  • Viral Core Proteins

Grants and funding

This work was supported by grants from Japan Society for the Promotion of Science (23790493), Japan Science and Technology Agency (01-117), Daiichi Sankyo Foundation of Life Science, Hayashi Memorial Foundation for Female Natural Scientists, Mochida Memorial Foundation for Medical and Pharmaceutical Research, Suhara Memorial Foundation, and Akiyama Life Science Foundation to AN, Japanese Initiative for Progress of Research on Infectious Disease for Global Epidemic (J-PRIDE) from Japan Agency for Medical Research and Development (AMED), Research Program on Emerging and Re-emerging Infectious Diseases from AMED, and a Grant-in-Aid for Scientific Research on Innovative Areas from the Ministry of Education, Culture, Science, Sports, and Technology (MEXT) of Japan (No. 16H06429, 16K21723, 16H06434) to YK. The funders had no role in study design, data collection and analysis, decision to publish or preparation of the manuscript.