title: Crimean-Congo hemorrhagic fever virus entry into host cells occurs through the multivesicular body and requires ESCRT regulators.
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.
authors.affiliation: Department of Virology and Immunology, Texas Biomedical Research Institute, San Antonio, Texas, United States of America.
authors.forename: Olena
authors.initials: O
authors.lastname: Shtanko
authors.affiliation: Laboratory of Regulation of Immunopoiesis, Institute for Clinical Immunology, Novosibirsk, Russian Federation.
authors.forename: Raisa A
authors.initials: RA
authors.lastname: Nikitina
authors.affiliation: Texas Institute of Biotechnology Education and Research, North American University, Houston, Texas, United States of America.
authors.forename: Cengiz Z
authors.initials: CZ
authors.lastname: Altuntas
authors.affiliation: Laboratory of Regulation of Immunopoiesis, Institute for Clinical Immunology, Novosibirsk, Russian Federation.
authors.forename: Alexander A
authors.initials: AA
authors.lastname: Chepurnov
authors.affiliation: Department of Virology and Immunology, Texas Biomedical Research Institute, San Antonio, Texas, United States of America.
authors.forename: Robert A
authors.initials: RA
authors.lastname: Davey
mesh_terms: D000310:Adrenal Gland Neoplasms / Q000276:immunology / Q000473:pathology / Q000821:virology*; D001692:Biological Transport; D015153:Blotting, Western; D004705:Endocytosis / Q000502:physiology; D056827:Endosomal Sorting Complexes Required for Transport / Q000502:physiology*; D003225:Hemorrhagic Fever Virus, Crimean-Congo / Q000502:physiology*; D054884:Host-Pathogen Interactions; D006801:Humans; D007124:Immunoenzyme Techniques; D057146:Multivesicular Bodies / Q000821:virology*; D019869:Phosphatidylinositol 3-Kinases / Q000235:genetics / Q000378:metabolism; D021381:Protein Transport; D012333:RNA, Messenger / Q000235:genetics; D060888:Real-Time Polymerase Chain Reaction; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014407:Tumor Cells, Cultured; D053586:Virus Internalization
chemical_list: D056827:Endosomal Sorting Complexes Required for Transport; D012333:RNA, Messenger; D019869:Phosphatidylinositol 3-Kinases