scholarly journals Independent Inhibition of the Polymerase and Deubiquitinase Activities of the Crimean–Congo Hemorrhagic Fever Virus Full-Length L-Protein

Proceedings ◽  
2020 ◽  
Vol 50 (1) ◽  
pp. 41
Author(s):  
Egor P. Tchesnokov ◽  
Ben A. Bailey-Elkin ◽  
Brian L. Mark ◽  
Matthias Götte
Keyword(s):  
Expression System ◽  
Hemorrhagic Fever ◽  
Fever Virus ◽  
Full Length ◽  
World Health ◽  
Rdrp Activity ◽  
Crimean Congo Hemorrhagic Fever ◽  
L Protein ◽  
Hemorrhagic Fever Virus ◽  
Research Activities

The Crimean–Congo hemorrhagic fever virus (CCHFV) is a segmented negative-sense RNA virus that can cause severe human disease. The World Health Organization (WHO) has listed CCHFV as a priority pathogen with an urgent need for enhanced research activities to develop effective countermeasures. We report on the expression, characterization, and inhibition of the CCHFV full-length L-protein that provides an important tool in this regard. The requirements for high biosafety measures hamper drug discovery and development efforts with infectious CCHFV. Hence, we decided to adopt a biochemical approach that targets the viral RNA-dependent RNA polymerase (RdRp). The CCHFV RdRp activity is part of a multifunctional L protein that is unusually large, with a molecular weight of ~450 kDa. The CCHFV L-protein also contains an ovarian tumor (OTU) domain that exhibits deubiquitinating (DUB) activity. Previous studies have shown that DUB activity interferes with innate immune responses and viral replication. Here, we utilized the baculovirus expression system and generated a full-length CCHFV L protein. RdRp activity was seen in the presence of divalent metal ions, and inhibition of RNA synthesis was demonstrated with nucleotide analogues. The ubiquitin analogue CC.4 inhibits the CCHFV-associated DUB activity of the full-length L protein and the isolated DUB domain to a similar extent. We have finally shown that RdRp and DUB activities are functionally independent. The full-length CCHFV L-protein provides an important tool for the discovery of antiviral agents. High-throughput screening (HTS) campaigns are now feasible. The same enzyme preparations can be utilized to identify polymerase and DUB inhibitors.

scholarly journals Small interfering RNAs are highly effective inhibitors regarding Crimean-Congo hemorrhagic fever virus replication in vitro

2020 ◽  
Author(s):  
Fanni Földes ◽  
Mónika Madai ◽  
Henrietta Papp ◽  
Gábor Kemenesi ◽  
Brigitta Zana ◽  
...  
Keyword(s):  
Rna Interference ◽  
Hemorrhagic Fever ◽  
Fever Virus ◽  
World Health ◽  
Dependent Manner ◽  
Small Interfering Rnas ◽  
Crimean Congo Hemorrhagic Fever ◽  
Hemorrhagic Fever Virus ◽  
Antiviral Therapies

AbstractCrimean-Congo hemorrhagic fever virus (CCHFV) is one of the prioritized diseases of World Health Organization, considering its potential to create a public health emergency and more importantly, the absence of efficacious drugs and/or vaccines regarding treatment. The highly lethal nature characteristic to CCHFV restricts research to BSL-4 laboratories, which complicates effective research and developmental strategies. In consideration of antiviral therapies, RNA interference can be used to suppress viral replication by targeting viral genes. RNA interference uses small interfering RNAs (siRNAs) to silence genes. The aim of our study was to design siRNAs that inhibit CCHFV replication and can serve as a basis for further antiviral therapies. A549 cells were infected with CCHFV after transfection with the siRNAs. Following 72 hours, nucleic acid from the supernatant was extracted for Droplet Digital PCR analysis. Among the investigated siRNAs we identified four effective candidates against all three segments of CCHF genome: one for the S and M segments, whilst two for the L segment. Consequently, blocking any segment of CCHFV leads to changes in the virus copy number that indicates an antiviral effect of the siRNAs in vitro. The most active siRNAs were demonstrated a specific inhibitory effect against CCHFV in a dose-dependent manner. In summary, we demonstrated the ability of specific siRNAs to inhibit CCHFV replication in vitro. This promising result can be used in future anti-CCHFV therapy developments.

scholarly journals Small Interfering RNAs Are Highly Effective Inhibitors of Crimean-Congo Hemorrhagic Fever Virus Replication In Vitro

Molecules ◽  
2020 ◽  
Vol 25 (23) ◽  
pp. 5771
Author(s):  
Fanni Földes ◽  
Mónika Madai ◽  
Henrietta Papp ◽  
Gábor Kemenesi ◽  
Brigitta Zana ◽  
...  
Keyword(s):  
Rna Interference ◽  
A549 Cells ◽  
Hemorrhagic Fever ◽  
Fever Virus ◽  
World Health ◽  
Small Interfering Rnas ◽  
Crimean Congo Hemorrhagic Fever ◽  
Hemorrhagic Fever Virus ◽  
Antiviral Therapies

Crimean-Congo hemorrhagic fever virus (CCHFV) is one of the prioritized diseases of the World Health Organization, considering its potential to create a public health emergency and, more importantly, the absence of efficacious drugs and/or vaccines for treatment. The highly pathogenic characteristic of CCHFV restricts research to BSL-4 laboratories, which complicates effective research and developmental strategies. In consideration of antiviral therapies, RNA interference can be used to suppress viral replication by targeting viral genes. RNA interference uses small interfering RNAs (siRNAs) to silence genes. The aim of our study was to design and test siRNAs in vitro that inhibit CCHFV replication and can serve as a basis for further antiviral therapies. A549 cells were infected with CCHFV after transfection with the siRNAs. Following 72 h, nucleic acid from the supernatant was extracted for RT Droplet Digital PCR analysis. Among the investigated siRNAs we identified effective candidates against all three segments of the CCHF genome. Consequently, blocking any segment of CCHFV leads to changes in the virus copy number that indicates an antiviral effect of the siRNAs. In summary, we demonstrated the ability of specific siRNAs to inhibit CCHFV replication in vitro. This promising result can be integrated into future anti-CCHFV therapy developments.

scholarly journals Crimean-Congo Hemorrhagic Fever Virus-Encoded Ovarian Tumor Protease Activity Is Dispensable for Virus RNA Polymerase Function

2009 ◽  
Vol 84 (1) ◽  
pp. 216-226 ◽  
Author(s):  
Éric Bergeron ◽  
César G. Albariño ◽  
Marina L. Khristova ◽  
Stuart T. Nichol
Keyword(s):  
Protease Activity ◽  
Ovarian Tumor ◽  
Antiviral Drug ◽  
Hemorrhagic Fever ◽  
Fever Virus ◽  
Crimean Congo Hemorrhagic Fever ◽  
L Protein ◽  
Hemorrhagic Fever Virus ◽  
Virus Rna ◽  
N Terminus

ABSTRACT Crimean-Congo hemorrhagic fever virus (CCHFV) is a tick-borne virus (genus Nairovirus, family Bunyaviridae) associated with high case fatality disease outbreaks in regions of Africa, Europe, and Asia. The CCHFV genome consists of three negative-strand RNA segments, S, M, and L. The unusually large virus L polymerase protein and the need for biosafety level 4 (BSL-4) containment conditions for work with infectious virus have hampered the study of CCHFV replication. The L protein has an ovarian tumor (OTU) protease domain located in the N terminus, which has led to speculation that the protein may be autoproteolytically cleaved to generate the active virus L polymerase and additional functions. We report the successful development of efficient CCHFV helper virus-independent S, M, and L segment minigenome systems for analysis of virus RNA and protein features involved in replication. The virus RNA segment S, M, and L untranslated regions were found to be similar in support of replication of the respective minigenomes. In addition, the OTU domain located in the N terminus of the expressed virus L protein was shown to be a functional protease. However, no evidence of L protein autoproteolytic processing was found, and the OTU protease activity was dispensable for virus RNA replication. Finally, physiologically relevant doses of ribavirin inhibited CCHFV minigenome replication. These results demonstrated the utility of the minigenome system for use in BSL-2 laboratory settings to analyze CCHFV biology and in antiviral drug discovery programs for this important public health and bioterrorism threat.

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