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Morbillivirus cell entry machinery: mechanisms, structures and antiviral drug discovery

Applicant Fotiadis Dimitrios
Number 183481
Funding scheme Sinergia
Research institution Institut für Biochemie und Molekulare Medizin Universität Bern
Institution of higher education University of Berne - BE
Main discipline Interdisciplinary
Start/End 01.04.2019 - 31.03.2023
Approved amount 2'048'200.00
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All Disciplines (4)

Discipline
Interdisciplinary
Experimental Microbiology
Biophysics
Organic Chemistry

Keywords (6)

Medicinal Chemistry; Molecular Virology; Structural Biology; Antiviral Drug Discovery; Morbillivirus Entry Machinery; Molecular Mechanisms

Lay Summary (French)

Lead
Développement de nouveaux inhibiteurs contre les morbillivirus tel que le virus de la rougeole.
Lay summary

Grâce à la disposition d’un vaccin très efficace, le virus de la rougeole est actuellement en voie d’éradication mondiale. Il est proposé, cependant, que le succès de la finalisation du programme d’éradication nécessitera également l’utilisation d’antiviraux spécifiques. Malheureusement de tels inhibiteurs n’existent pas, ou sont en cours de développement.

Notre projet s’articule donc autour du développement d’inhibiteurs spécifiques, notamment,  contre le virus de la rougeole. Pour cela, nous avons combiné les expertises suivantes: virologie, biologie structurale et chimie/bio-informatique. Plus précisément, nous développons, d’une part, de nouveaux tests cellulaires (ciblant l’étape d’entrée du virus dans la cellule) permettant l’identification de nouvelles molécules inhibitrices par criblage à haut débit. D’autre part, nous employons la technologie de cryo-microscopie électronique afin de déterminer à haute résolution la structure tridimensionnelle des protéines permettant l’entrée du virus dans la cellule. De telles structures devraient nous permettre, dans un second temps, de raffiner par conception basée sur la structure et synthèse chimique les molécules inhibitrices. Finalement, ces approches ont également le potentiel de délivrer des informations essentiels en ce qui concerne les mécanismes de résistances des virus face à ces nouveaux antiviraux et, de ce fait, les améliorer.

Nous sommes convaincus que le développement dans un futur proche de nouveaux médicaments efficaces contre les morbillivirus et le virus de la rougeole nécessite le travail en commun d’expertises diverses et complémentaires, tel que proposé dans ce projet multidisciplinaire.

Direct link to Lay Summary Last update: 06.12.2018

Responsible applicant and co-applicants

Employees

Project partner

Associated projects

Number Title Start Funding scheme
157704 Direct electron detector and phase plate for cryo-transmission electron microscopy of biological samples 01.12.2014 R'EQUIP
153281 Unraveling Paramyxovirus Cell Entry 01.05.2014 Project funding (Div. I-III)

Abstract

Background. Despite efficient available vaccines, measles virus (MeV) and canine distemper virus (CDV), two closely related enveloped RNA viruses belonging to the Morbillivirus genus of the Paramyxoviridae family, still cause important global health and economic impairments. Sub-optimal vaccine delivery in developing countries and vaccination refusal induced by unfounded anxiety concerning the vaccine’s safety in western countries continue to foster MeV outbreaks. Post-exposure prophylaxis with antivirals has been proposed as a novel strategy to complement vaccination programs by filling herd immunity gaps. On the other hand, bioengineered attenuated MeV are used to treat different types of cancer; a very promising platform that needs further efficacy and biosafety improvements. Furthermore, CDV can readily cross the species barrier and kill numerous wild animals, including endangered species. Although two inhibitors were recently tested in animal models as potential drug candidates, no FDA-approved anti-MeV/CDV drug is currently available. Specific aims. Of major importance, MeV and CDV are characterized by only one serotype, thus being unable to escape anti-surface glycoproteins’ immunity. This spotlights the cell entry process, which is controlled by two interacting envelope glycoproteins (termed H and F), as an attractive “Achilles heel” for antiviral drugs’ development. Hence, the major aims of our Sinergia research project are:I. To gain deep functional and structural insights into the molecular cell entry mechanism of MeV and CDVII. To discover MeV and CDV entry inhibitors as next-generation antiviral drugsExperimental design. To successfully achieve Aim 1, we will apply established state-of-the-art as well as newly developed innovative bioassays to identify and characterize functional microdomains of both glycoproteins. In parallel, we will rationally design recombinant, conformation-stabilized, soluble and membrane H and F proteins as well as the H/F membrane protein complex. Such engineered soluble and membrane proteins will then represent the basis for (i) structural determination (single particle cryo-electron microscopy and X-ray crystallography), and (ii) identification of neutralizing nanobodies (nNbs) upon llamas’ immunization. Beyond potential direct clinical benefits of nNbs as viral entry inhibitors, nNbs may act as powerful molecular scaffolds to further stabilize engineered soluble protein variants in desired conformational states. Aim 2 will focus on the discovery of small molecule-based antiviral compounds. To this aim, we will use our newly established next-generation “targeted” stable cell-based fusion assays for high throughput screening (HTS). Furthermore, to increase the number of identified hit compounds, virtual HTS and structure-based de novo drug design based on available X-ray co-crystal structures (and later on those determined in Aim 1) will be performed. Importantly, functional microdomains (e.g., discovered in Aim 1), will provide key “druggable” protein targets. Next, upon hit validation as effective entry inhibitors with recombinant live-viruses, the most promising antiviral compounds will be submitted to iterative cycles of medicinal chemistry for efficacy refinement towards clinical relevance. Finally, candidate inhibitors with optimized drug-like profiles will be tested in a well-established in vivo model of morbillivus-induced pathogenesis.Significance. We are confident that our integrated empirical and rational ambitious approaches will synergize to successfully discover new potent MeV/CDV cell entry inhibitors. Overall, such inhibitors may not only enable the containment of ongoing epidemics, which in turn may pave the way to support the WHO-targeted global MeV eradication, but offer attractive non-invasive molecular tools for careful and rational control of oncolytic MeV/CDV vectors.
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