rologie i - European Congress of Virology

5 th European Congress of VirologyFriday 13 th September 2013, 8h30 – 10h30WORKSHOP 15: “HIGHLY PATHOGENIC VIRUSES”Chairpersons: Ake LUNDKVIST (Stockholm, SWEDEN) &Viktor VOLCHKOV (Lyon, FRANCE)AmphitheaterKEYNOTE:Transport and assembly of filovirusesLarissa KOLESNIKOVA, Gordian SCHUDT, Olga DOLNIK, andStephan BECKERInstitut für Virologie, Philipps-Universität Marburg, Hans-Meerwein-Str.2, 35043 Marburg, GERMANYThe family of Filoviridae comprises Marburg and Ebola virus which bothcause severe life-threatening diseases characterized by high fever, rash,thrombocytopenia and hemorrhagic diathesis. The pathogenesis of the syndromeis not completely understood; probably the dynamic replication offiloviruses in the infected host leads to an uncoordinated immune response.Detailed understanding of the basic mechanisms of filoviral assembly andinteraction with host cells is key to identify targets of antiviral intervention.The first sign of Filovirus replication that can be detected microscopicallyin the infected cell is the formation of inclusions in the perinuclear region.Inclusions contain all filoviral nucleocapsid proteins (NP, VP35, VP30,VP24, and L) but also the matrix protein VP40 and a number of cellularproteins. Viral nucleocapsids are formed within the inclusions by specificinteractions among the viral proteins. Mature nucleocapsids are thentransported across the cytoplasm to the plasma membrane with the helpof the actin cytoskeleton. The matrix protein accumulates at the plasmamembrane in a compartment that contains markers of the late endosomeand is probably of endosomal origin. In presence of the matrix protein,the only glycoprotein GP is recruited via the classical secretory pathwayto the peripheral matrix protein containing compartment. In the cell peripherynucleocapsids are associated with the matrix protein and channeledinto filopodia, the site of filoviral release. Nucleocapsids inside filopodiaare cotransported together with the unconventional motor protein myosin10. Transport of nucleocapsids and release of viral particles at filopodia issupported by the cellular ESCRT machinery.ORAL COMMUNICATIONSREF O89Mopeia virus and recombinant Lassa virus containing mutations intothe exonuclease of the nucleoprotein, but not wild type Lassa virus,induce a strong release of CXC and CC chemokines by human antigenpresenting cellsSylvain BAIZE 1,2 , Delphine PANNETIER 1,3 , Stéphanie REYNARD 1,2 ,Marion RUSSIER 1,21 Unité de Biologie des Infections Virales Emergentes, Institut Pasteur,Lyon, FRANCE; 2 International Center for Infectiology Research, Universitéde Lyon, Lyon, FRANCE; 3 Laboratoire P4 Inserm Jean Mérieux,Inserm US003, Lyon, FRANCEThe pathogenesis of Lassa fever, a hemorrhagic fever endemic in WestAfrica, is still unclear. We previously compared Lassa virus (LASV) withits genetically close but non pathogenic homolog Mopeia virus (MOPV)and demonstrated that the strong activation of antigen presenting cells(APC), including type I IFN production, observed in response to MOPVprobably plays a crucial role in controlling infection. Here, we show thathuman macrophages (MP) produced strong levels of CC and CXC chemokinesin response to MOPV infection, while dendritic cells (DC) releasedonly moderate levels of CXC chemokines. However, in the presence ofautologous T cells, DC were able to produce CC and CXC chemokines.Production of chemokines resulted from type I IFN synthesis, as levelsof both mediators were strongly correlated and as neutralization of typeI IFN led to inhibition of chemokine production. In contrast, only weaklevels of CXCL 10 and CXCL 11 were observed in response to LASV.Strikingly, the recombinant LASV harbouring mutations abrogating theability of NP to inhibit type I IFN response induces a massive synthesisof CC and CXC chemokines in both DC and MP. These resultsconfirm the crucial role of arenavirus NP in immunosuppression andpathogenicity. In addition, these differences in chemokine production mayprofoundly impact on the generation of virus specific T cell responses andthus, could be involved in the difference of pathogenicity between bothviruses.REF O90Soluble proteins of Ebola virus bind and activate dendritic cells andmacrophages causing release of pro and anti inflammatory cytokinesBeatriz ESCUDERO PÉREZ, Philip LAWRENCE, Viktor VOLCHKOVCIRI, INSERM U1111, Lyon, FRANCEEbola virus (EBOV) is a member of Filoviridae family and causes hemorrhagicfever with high fatality rates. Through RNA editing the EBOV GPgene codes for both the highly glycosylated surface protein (GP) and thesecreted glycoprotein sGP. Surface GP is responsible for virus attachmentand membrane fusion, but is also released from cells in a soluble form(shed GP) due to cleavage by cellular metalloprotease TACE.Both dendritic cells (DCs) and macrophages serve as early targets of EBOVand play a prominent role during infection. No cellular target has yetbeen identified for EBOV soluble proteins. Here, for the first time wedemonstrate that EBOV soluble proteins bind to human monocyte derivedDCs and macrophages. Importantly, we demonstrate that binding of shedGP but not sGP causes an activation of CD40, CD80 and CD86 expressionand an increase in levels of mRNA encoding TNFa, IL6, IL10 and IL12p40.Treatment of DCs and macrophages with shed GP resulted in release ofboth pro and anti inflammatory cytokines, as demonstrated by multiplexELISA. We have also revealed that the glycosylation pattern of shed GPis crucial in mediating this activation.Overall, this study suggests that shed GP but not sGP is responsible forthe early stimulation of human DCs and macrophages and thus may playa role in the dysregulation of host immune responses that, combined withmassive virus replication and virus induced cell damage, leads to a septicshock like syndrome and high mortality.REF O91Crimean Congo Hemorrhagic Fever Virus infected human monocytederived dendritic cells basolaterally transmits infection to humanepithelial cellsCecilia ANDERSSON 1,2 , Ali MIRAZIMI 1,2,31 Department of Microbiology, Tumor and Cell Biology, Karolinska Institute,Stockholm, SWEDEN; 2 Department of Preparedness, SwedishInstitute for Communicable Disease, Solna, SWEDEN; 3 National VeterinaryInstitute, SVA, Uppsala, SWEDENCrimean Congo hemorrhagic fever virus (CCHFV) is an arthropod bornepathogen that in humans causes a severe disease with high case fatalityrates, Crimean Congo Hemorrhagic Fever characterized by hemorrhageand vascular leakage. The mechanisms determining the pathogenesis ofthis virus is however largely unknown. We have previously shown thatCCHFV entry and release take place basolaterally and that the infectionVirologie, Vol 17, supplément 2, septembre 2013S75