Crimean-Congo hemorrhagic fever virus entry into host cells occurs through the multivesicular body and requires ESCRT regulators

PLoS Pathog. 2014 Sep 18;10(9):e1004390. doi: 10.1371/journal.ppat.1004390. eCollection 2014 Sep.

Abstract

Crimean-Congo hemorrhagic fever virus (CCHFV) is a tick-borne bunyavirus causing outbreaks of severe disease in humans, with a fatality rate approaching 30%. There are no widely accepted therapeutics available to prevent or treat the disease. CCHFV enters host cells through clathrin-mediated endocytosis and is subsequently transported to an acidified compartment where the fusion of virus envelope with cellular membranes takes place. To better understand the uptake pathway, we sought to identify host factors controlling CCHFV transport through the cell. We demonstrate that after passing through early endosomes in a Rab5-dependent manner, CCHFV is delivered to multivesicular bodies (MVBs). Virus particles localized to MVBs approximately 1 hour after infection and affected the distribution of the organelle within cells. Interestingly, blocking Rab7 activity had no effect on association of the virus with MVBs. Productive virus infection depended on phosphatidylinositol 3-kinase (PI3K) activity, which meditates the formation of functional MVBs. Silencing Tsg101, Vps24, Vps4B, or Alix/Aip1, components of the endosomal sorting complex required for transport (ESCRT) pathway controlling MVB biogenesis, inhibited infection of wild-type virus as well as a novel pseudotyped vesicular stomatitis virus (VSV) bearing CCHFV glycoprotein, supporting a role for the MVB pathway in CCHFV entry. We further demonstrate that blocking transport out of MVBs still allowed virus entry while preventing vesicular acidification, required for membrane fusion, trapped virions in the MVBs. These findings suggest that MVBs are necessary for infection and are the sites of virus-endosome membrane fusion.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Adrenal Gland Neoplasms / immunology
  • Adrenal Gland Neoplasms / pathology
  • Adrenal Gland Neoplasms / virology*
  • Biological Transport
  • Blotting, Western
  • Endocytosis / physiology
  • Endosomal Sorting Complexes Required for Transport / physiology*
  • Hemorrhagic Fever Virus, Crimean-Congo / physiology*
  • Host-Pathogen Interactions*
  • Humans
  • Immunoenzyme Techniques
  • Multivesicular Bodies / virology*
  • Phosphatidylinositol 3-Kinases / genetics
  • Phosphatidylinositol 3-Kinases / metabolism
  • Protein Transport
  • RNA, Messenger / genetics
  • Real-Time Polymerase Chain Reaction
  • Reverse Transcriptase Polymerase Chain Reaction
  • Tumor Cells, Cultured
  • Virus Internalization*

Substances

  • Endosomal Sorting Complexes Required for Transport
  • RNA, Messenger
  • Phosphatidylinositol 3-Kinases

Grants and funding

This work was supported by Defense Threat Redaction Agency grant HDTRA1-12-1-0002 FRBAA09-6H-2-0043 to RAD and AAC, URL: https://www.fbo.gov/index?s=opportunity&mode=form&id=d29f1652fad259d95b6b3bf2292bcf89&tab=core&_cview=1. A postdoctoral fellowship to OS was generously provided by the Douglass Foundation. RAD is supported by the Ewing Halsell Foundation, URL: http://www.ewinghalsell.org. The funders had no role in study design, data collection, analysis, decision to publish, or preparation of the manuscript.