Project

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Targeting the processing of arenavirus glycoprotein for anti-viral therapy

English title Targeting the processing of arenavirus glycoprotein for anti-viral therapy
Applicant Kunz Stefan
Number 135536
Funding scheme Project funding
Research institution Institut de Microbiologie - CHUV Faculté de Biologie et Médecine Université de Lausanne
Institution of higher education University of Lausanne - LA
Main discipline Medical Microbiology
Start/End 01.04.2011 - 31.03.2014
Approved amount 216'000.00
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Keywords (5)

Arenavirus; Glycoprotein; Anti-viral drugs; Protease; Emerging virus

Lay Summary (English)

Lead
Lay summary
Several arenaviruses have emerged as causative agents of severe viral hemorrhagic fevers with high mortality in humans and represent serious public health problems. A highly predictive factor for disease outcome in human arenavirus infection is the viral load, indicating a close competition between the virus and the patient’s immune system. The goal of our project is the development of novel anti-viral drugs that limit viral replication and provide the patient’s immune system a window of opportunity to develop anti-viral immune responses, to control the infection. Arenavirus infection in the host cell critically depends on cellular factors including the enzyme site 1 protease. During infection, site 1 protease is involved in the production of a functional viral envelope by processing the main surface protein of the virus, the viral glycoprotein. In our project, we will investigate how the viral glycoprotein is recognized by the protease. We will further try to obtain information of the structure of the protease and the interaction with the viral glycoprotein. This information will then be used to design novel drugs that target the protease and block its function in the context of the virus infection. Considering the number of people affected and the current lack of a licensed vaccine and efficacious drugs, arenaviruses belong arguably to the most neglected emerging human pathogens. Our project will help to better understand these viruses and to develop novel therapeutics to combat human arenavirus infection. 
Direct link to Lay Summary Last update: 21.02.2013

Responsible applicant and co-applicants

Employees

Name Institute

Publications

Publication
Differential recognition of Old World and New World arenavirus envelope glycoproteins by subtilisin kexin isozyme 1 (SKI-1)/site 1 protease (S1P).
Burri Dominique J, da Palma Joel Ramos, Seidah Nabil G, Zanotti Giuseppe, Cendron Laura, Pasquato Antonella, Kunz Stefan (2013), Differential recognition of Old World and New World arenavirus envelope glycoproteins by subtilisin kexin isozyme 1 (SKI-1)/site 1 protease (S1P)., in Journal of virology, 87(11), 6406-14.
The lectin ERGIC-53 goes viral.
Pasquato Antonella, Kunz Stefan (2013), The lectin ERGIC-53 goes viral., in Cell host & microbe, 14(5), 485-7.
The role of proteolytic processing and the stable signal peptide in expression of the Old World arenavirus envelope glycoprotein ectodomain.
Burri Dominique J, Pasquato Antonella, da Palma Joel Ramos, Igonet Sebastien, Oldstone Michael B A, Kunz Stefan (2013), The role of proteolytic processing and the stable signal peptide in expression of the Old World arenavirus envelope glycoprotein ectodomain., in Virology, 436(1), 127-33.
Current drug discovery strategies against arenavirus infections.
Pasquato Antonella, Burri Dominique J, Kunz Stefan (2012), Current drug discovery strategies against arenavirus infections., in Expert review of anti-infective therapy, 10(11), 1297-309.
Evaluation of the anti-arenaviral activity of the subtilisin kexin isozyme-1/site-1 protease inhibitor PF-429242.
Pasquato Antonella, Rochat Cylia, Burri Dominique J, Pasqual Giulia, de la Torre Juan Carlos, Kunz Stefan (2012), Evaluation of the anti-arenaviral activity of the subtilisin kexin isozyme-1/site-1 protease inhibitor PF-429242., in Virology, 423(1), 14-22.
Molecular characterization of the processing of arenavirus envelope glycoprotein precursors by subtilisin kexin isozyme-1/site-1 protease.
Burri Dominique J, Pasqual Giulia, Rochat Cylia, Seidah Nabil G, Pasquato Antonella, Kunz Stefan (2012), Molecular characterization of the processing of arenavirus envelope glycoprotein precursors by subtilisin kexin isozyme-1/site-1 protease., in Journal of virology, 86(9), 4935-46.
Viral envelope glycoprotein processing by proprotein convertases.
Pasquato Antonella, da Palma Joel Ramos, Galan Clara, Seidah Nabil G, Kunz Stefan, Viral envelope glycoprotein processing by proprotein convertases., in Antiviral research.

Collaboration

Group / person Country
Types of collaboration
University of Padua Italy (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
- Research Infrastructure
Institut de Recherches Cliniques Canada (North America)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
- Research Infrastructure
- Exchange of personnel
EPFL Switzerland (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Research Infrastructure
Scripps Research Institute La Jolla United States of America (North America)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
- Research Infrastructure

Scientific events

Active participation

Title Type of contribution Title of article or contribution Date Place Persons involved
International Conference on Negative Strand Viruses Poster Differential recognition of arenavirus glycoproteins by SKI-1/S1P 16.06.2013 Granada, Spain Pasquato Antonella; Kunz Stefan;
USGEB meeting Talk given at a conference Targeting Host Cell Proteases for Anti-Viral Therapy 06.02.2012 Lausanne, Switzerland Kunz Stefan;
Gordon Conference: Viruses & Cells Poster Evaluation of the SKI-1/S1P inhibitor PF-429242 as anti-arenaviral drug 15.05.2011 Lucca, Italy Pasquato Antonella; Kunz Stefan;


Self-organised

Title Date Place
Swiss Virolgy Meeting 05.02.2013 Thun, Switzerland
Swiss Workshop in Fundamental Virology 29.08.2011 Thun, Switzerland, Switzerland

Associated projects

Number Title Start Funding scheme
143754 Immunoengineering a synthetic vaccine against emerging human pathogenic viruses 01.10.2012 Interdisciplinary projects
132844 Host cell invasion by Lassa virus 01.01.2011 Project funding
149746 Host cell invasion by Lassa virus 01.01.2014 Project funding
120250 Targeting the processing of arenavirus glycoprotein for anti-viral therapy 01.04.2008 Project funding

Abstract

Several arenaviruses have emerged as causative agents of severe viral hemorrhagic fevers with high mortality in humans and represent serious public health problems. A highly predictive factor for disease outcome in human arenavirus infection is the viral load, indicating a close competition between viral spread and replication and the patient’s immune system. Anti-viral drugs that limit viral replication and spread may provide the patient’s immune system a window of opportunity to develop anti-viral immune responses, to control, and ultimately clear the virus. The development of novel drugs targeting different steps in the arenavirus life cycle is therefore a promising strategy to combat arenavirus infections.Arenaviruses are enveloped RNA viruses with a non-lytic life cycle confined to the cytoplasm. A crucial step in their life cycle is the biosynthesis of the viral envelope glycoprotein (GP) responsible for virus attachment and entry. Processing of the GP precursor (GPC) by the cellular proprotein convertase site 1 protease (S1P)/subtilisin-kexin-isozyme-1 (SKI-1), is crucial for cell-to-cell propagation of infection and production of infectious virus. During the initial funding period of our project, we characterized the molecular interaction between SKI-1/S1P and arenavirus GPCs. Our structure-function analysis revealed unusual features of the SKI-1/S1P-GPC interaction that provide the basis for the present renewal. We identified a step in SKI-1/S1P maturation, namely the autoprocessing of its prodomain at the B/B’ site, that was crucial for processing of arenaviral GPC, but not cellular substrates. In a follow-up study we will elucidate the molecular basis for this difference and will evaluate targeting this autoprocessing step as a novel anti-arenaviral strategy. Our studies further demonstrated that, in contrast to other viruses, arenavirus GPCs cannot be processed at the cell surface and that unprocessed arenavirus GPC adopts a conformation distinct from mature GP. We hypothesize that this feature of arenaviruses may be the reason that arenaviruses selectively incorporate mature, processed GP into virions. In the continuation of our project we will unravel the molecular basis of this “quality control” mechanism investigating the impact of GPC processing on interactions of GPC with viral and cellular factors during virion assembly and budding. Such a control mechanism may not only reveal novel aspects of basic arenavirus biology, but could also be exploited as a possible target for therapeutic intervention. During the first funding period, we performed a proof-of-principle study demonstrating that targeting of the proteolytic processing of arenavius GPC is a promising anti-viral strategy. In a collaborative effort, we evaluated a novel small molecule inhibitor of SKI-I/S1P and found potent anti-viral activity. This novel drug further shows additive effects with the clinically used ribavirin in acute and chronic arenavirus infection, making it a promising candidate for further evaluation. However, considering the important roles of SKI-I/S1P in cell biology, the development of inhibitors that specifically block processing of viral GPCs without affecting cellular substrates represents a major unaddressed issue and is in the focus of the present grant renewal. We will base our drug discovery strategy on our finding that SKI-I/S1P B/B’ prodomain processing is specifically required for the enzyme’s ability to process arenavirus GPCs, but not cellular substrates. A major obstacle for structure-function studies on the molecular interaction between SKI-1/S1P and its cellular and viral substrates as well as the development of specific SKI-1/S1P inhibitors is the current lack of structural information. To close this gap, we have established collaboration with a highly respected and very productive structural biology laboratory. Our collaborative efforts aim at the resolution of the structure of the catalytic domain of SKI-1/S1P and if possible the whole ectodomain of the protease, alone and in complex with viral substrates and candidate inhibitors. The availability of the first high-resolution structural data on SKI-I/S1P will allow fundamental novel insights into the interaction of SKI-I/S1P with viral and cellular substrates and pave the way for rational design of SKI-I/S1P inhibitors tailored to specific needs.
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