Ebola virus crisis. Prof. Viktor Volchkov. Molecular basis of viral pathogenicity

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1 Ebola virus crisis Prof. Viktor Volchkov Molecular basis of viral pathogenicity International Centre for Research in Infectiology (CIRI), INSERM Claude Bernard University Lyon-1, Lyon, France Leem Press Workshop March 10, 2015

2 Jean Mérieux INSERM BSL 4 Laboratory

3 The molecular basis of high pathogenicity Emergency of highly pathogenic viruses Lessons from current Ebola crisis

4 BSL P4 viral agents Ebola and Marburg viruses / Filoviridae Nipah virus / Henipaviridae Crimean-Congo hemorrhagic fever virus / Bunyaviridae

5 BSL P4 viral agents Infections kill up to 60-90% of patients Spread through human-to-human or animal-to-human contacts Intercontinental virus transfer / Potential bio-terrorism agent Currently no vaccines or treatments are available for human use Molecular bases of high pathogenicity are not well understood

6 Ebola virus 3 NP GP L 5 Enveloped, non-segmented negative-stranded RNA containing virus 7 structural proteins and 3 non-structural soluble proteins Surface glycoprotein: GP membrane Matrix protein VP40 VP24 Genomic RNA. Nucleoprotein(NP). VP35. VP30. Polymerase (L)

7 Massive virus replication

8 EBOV and MARV GP/shedGP VP35/VP24 Innate Immune responses Inflammation Oxidative stress VP24 VP30/VP24 RNA Synthesis/Virus assembly Masking phenomenon/ GP gene editing and virus adaptation Reynard et al., J Virol 2009; Volchkova et al., JID 2011 Role of EBOV GP shedding Esqudero-Perez et al., Plos Pathogenes 2014 VP35 and VP24 are IFN antagonists Prins et al., J Virol 2010; Mateo et al., J Virol Molecular determinants of virulence Mateo et al., JID 2011 Disregulation of host inflammatory responses Leung et al., JID 2011; Page et al., Cell Reports 2014 Molecular switch: RNA replication versus transcription Martinez et al., J Virol 2010, JID 2011 Role of VP24 in viral nucleocapsids assembly Mateo et al., JID 2011 High pathogenicity

9 Introduction Shedding of EBOV surface glycoprotein GP Shed GP Block virus neutralizing antibodies Membrane GP sgp Shed GP EBOV-infected cell EBOV virion

10 Results Shed GP of Ebola virus Triggers Systemic Immune Activation and Increased Vascular Permeability TLR-4 Non-infected cells EBOV EBOV-infected cell Shed GP TNF-α IL-6 IL-12 IL-10 etc. Transcriptional activation and release of cytokines Blood cells / fluid Endothelial cells DC/MØ B/T lymphocytes Hepatocyte, renal cells, etc PLOS Pathogens, 2014 Increase of permeability Imballance d inflammation Activati on Organ failure

11 Factors that contribute to high pathogenicity High efficiency of replication and viral pantropism Multiple antagonists of innate immunity Excessive and dysregulated host responses to viral replication «Loaded gun»

12 Virus host interaction (I) Natural reservoir Low virus replication Asymptomatic infection High level of virus adaptation

13 Virus host interaction (II) Accidental hosts High level of virus replication High pathogenicity Low level of virus adaptation

14 Virus emergence (I) Accidental hosts Natural reservoir

15 Virus emergence (II) Local infections Strict Quarantine End of outbreak Hospital Nosocomial infection Difficult to apply quarantine Low Level Health Care Virus spread

16 Lessons from current Ebola crisis: Always keep watching for known highly pathogenic viruses. Preparedness: Diagnosis Vaccine For all known highly pathogenic viruses. Therapeutics Exploring the link between Academic Science and Industrials. Keep moving forward. Learn more on molecular basis of high pathogenicity. Search for new, related viruses (African henipa- and filoviruses)

17 BACK UP

18 Research tools Reverse genetics approach T7 promoter Ribozyme NP GP L pfl-ebov NP pfl-ebov L NC genes (T7 promoter) L NP T7 NP T7 mrna`s BSR T7/5 cells L T T7 6 Recombinant Ebola virus (cross section) Volchkov et al Science 2001 Ebola and Marburg viruses, Nipah virus and CCHF virus

19 weight(g) weight(g) Results EBOV mutant is completely attenuated WT days post infection days post infection αvp40 D D NE D days post infection JID, 2015