scholarly journals Crimean-Congo Hemorrhagic Fever Virus Glycoprotein Processing by the Endoprotease SKI-1/S1P Is Critical for Virus Infectivity

2007 ◽  
Vol 81 (23) ◽  
pp. 13271-13276 ◽  
Author(s):  
Éric Bergeron ◽  
Martin J. Vincent ◽  
Stuart T. Nichol
Keyword(s):  
Infectious Virus ◽  
Virus Assembly ◽  
Hemorrhagic Fever ◽  
Fever Virus ◽  
Virus Infectivity ◽  
Crimean Congo Hemorrhagic Fever ◽  
Hemorrhagic Fever Virus ◽  
Viral Glycoproteins ◽  
Infected Cells ◽  
Glycoprotein Processing

ABSTRACT Crimean-Congo hemorrhagic fever virus (CCHFV) causes severe human disease. The CCHFV medium RNA encodes a polyprotein which is proteolytically processed to yield the glycoprotein precursors PreGn and PreGc, followed by structural glycoproteins Gn and Gc. Subtilisin kexin isozyme-1/site-1 protease (SKI-1/S1P) plays a central role in Gn processing. Here we show that CCHFV-infected cells deficient in SKI-1/S1P produce no infectious virus, although PreGn and PreGc accumulated normally in the Golgi apparatus, the site of virus assembly. Only nucleoprotein-containing particles which lacked virus glycoproteins (Gn/Gc or PreGn/PreGc) were secreted. Complementation of SKI-1/S1P-deficient cells with a SKI-1/S1P expression vector restored release of infectious virus (>106 PFU/ml), confirming that SKI-1/S1P processing is required for incorporation of viral glycoproteins. SKI-1/S1P may represent a promising antiviral target.

scholarly journals Human MxA Protein Inhibits the Replication of Crimean-Congo Hemorrhagic Fever Virus

2004 ◽  
Vol 78 (8) ◽  
pp. 4323-4329 ◽  
Author(s):  
Ida Andersson ◽  
Linda Bladh ◽  
Mehrdad Mousavi-Jazi ◽  
Karl-Eric Magnusson ◽  
Åke Lundkvist ◽  
...  
Keyword(s):  
Antiviral Activity ◽  
Hemorrhagic Fever ◽  
Inhibitory Effect ◽  
Fever Virus ◽  
Progeny Virus ◽  
Crimean Congo Hemorrhagic Fever ◽  
Viral Genomes ◽  
Virus Particles ◽  
Hemorrhagic Fever Virus ◽  
Infected Cells

ABSTRACT Crimean-Congo hemorrhagic fever virus (CCHFV) belongs to the genus Nairovirus within the family Bunyaviridae and is the causative agent of severe hemorrhagic fever. Despite increasing knowledge about hemorrhagic fever viruses, the factors determining their pathogenicity are still poorly understood. The interferon-induced MxA protein has been shown to have an inhibitory effect on several members of the Bunyaviridae family, but the effect of MxA against CCHFV has not previously been studied. Here, we report that human MxA has antiviral activity against CCHFV. The yield of progeny virus in cells constitutively expressing MxA was reduced up to 1,000-fold compared with control cells, and accumulation of viral genomes was blocked. Confocal microscopy revealed that MxA colocalizes with the nucleocapsid protein (NP) of CCHFV in the perinuclear regions of infected cells. Furthermore, we found that MxA interacted with NP by using a coimmunoprecipitation assay. We also found that an amino acid substitution (E645R) within the C-terminal domain of MxA resulted in a loss of MxA antiviral activity and, concomitantly, in the capacity to interact with CCHFV NP. These results suggest that MxA, by interacting with a component of the nucleocapsid, prevents replication of CCHFV viral RNA and thereby inhibits the production of new infectious virus particles.

scholarly journals Identification of a Novel C-Terminal Cleavage of Crimean-Congo Hemorrhagic Fever Virus PreGN That Leads to Generation of an NSM Protein

2007 ◽  
Vol 81 (12) ◽  
pp. 6632-6642 ◽  
Author(s):  
Louis A. Altamura ◽  
Andrea Bertolotti-Ciarlet ◽  
Jeffrey Teigler ◽  
Jason Paragas ◽  
Connie S. Schmaljohn ◽  
...  
Keyword(s):  
Transmembrane Domain ◽  
Virus Assembly ◽  
Nonstructural Protein ◽  
Hemorrhagic Fever ◽  
Fever Virus ◽  
Internal Deletion ◽  
Crimean Congo Hemorrhagic Fever ◽  
Hemorrhagic Fever Virus ◽  
Endoproteolytic Cleavage ◽  
Golgi Compartment

ABSTRACT The structural glycoproteins of Crimean-Congo hemorrhagic fever virus (CCHFV; genus Nairovirus, family Bunyaviridae) are derived through endoproteolytic cleavage of a 1,684-amino-acid M RNA segment-encoded polyprotein. This polyprotein is cotranslationally cleaved into the PreGN and PreGC precursors, which are then cleaved by SKI-1 and a SKI-1-like protease to generate the N termini of GN and GC, respectively. However, the resulting polypeptide defined by the N termini of GN and GC is predicted to be larger (58 kDa) than mature GN (37 kDa). By analogy to the topologically similar M segment-encoded polyproteins of viruses in the Orthobunyavirus genus, the C-terminal region of PreGN that contains four predicted transmembrane domains may also contain a nonstructural protein, NSM. To characterize potential PreGN C-terminal cleavage events, a panel of epitope-tagged PreGN truncation and internal deletion mutants was developed. These constructs allowed for the identification of a C-terminal endoproteolytic cleavage within, or very proximal to, the second predicted transmembrane domain following the GN ectodomain and the subsequent generation of a C-terminal fragment. Pulse-chase experiments showed that PreGN C-terminal cleavage occurred shortly after synthesis of the precursor and prior to generation of the GN glycoprotein. The resulting fragment trafficked to the Golgi compartment, the site of virus assembly. Development of an antiserum specific to the second cytoplasmic loop of PreGN allowed detection of cell-associated NSM proteins derived from transient expression of the complete CCHFV M segment and also in the context of virus infection.

scholarly journals Basolateral Entry and Release of Crimean-Congo Hemorrhagic Fever Virus in Polarized MDCK-1 Cells

2006 ◽  
Vol 81 (5) ◽  
pp. 2158-2164 ◽  
Author(s):  
Anne-Marie Connolly-Andersen ◽  
Karl-Erik Magnusson ◽  
Ali Mirazimi
Keyword(s):  
Epithelial Cells ◽  
Viral Entry ◽  
Hemorrhagic Fever ◽  
Fever Virus ◽  
Crimean Congo Hemorrhagic Fever ◽  
Hemorrhagic Fever Virus ◽  
Infected Cells ◽  
Polarized Epithelial Cells ◽  
A Site ◽  
First Time

ABSTRACT Crimean-Congo hemorrhagic fever virus (CCHFV) is an etiological agent of a disease with mortality rates in patients averaging 30%. The disease is characterized by fever, myalgia, and hemorrhage. Mechanisms underlying the hemorrhage have to our knowledge not been elucidated for CCHFV. Possibly, a direct or indirect viral effect on tight junctions (TJ) could cause the hemorrhage observed in patients, as TJ play a crucial role in vascular homeostasis and can cause leakage upon deregulation. Moreover, there is no knowledge regarding the site of entry and release of CCHFV in polarized epithelial cells. Such cells represent a barrier to virus dissemination within the host, and as a site of viral entry and release, they could play a key role in further spread. For the first time, we have shown preferential basolateral entry of CCHFV in Madin-Darby canine kidney 1 (MDCK-1) epithelial cells. Furthermore, we demonstrated basolateral release of CCHFV in polarized epithelial cells. Interestingly, by measuring transepithelial electrical resistance, we found no effect of CCHFV replication on the function of TJ in this study. Neither did we observe any difference in the localization of the TJ proteins ZO-1 and occludin in CCHFV-infected cells compared to mock-infected cells.

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