rologie i - European Congress of Virology

5 th European Congress of Virologypotentially contribute to the formation of neutralizing antibodies directedto E.The specificity of CD4+ T cells was analyzed using an IL 2 ELISpot assayand these experimental results were compared with epitope predictions forthe HLA class II alleles (DR, DP, DQ) of each individual.Our results show that the CD4+ T cell response to peptides of the C proteinis overrepresented after both, infection and vaccination. Despite strongindividual variation, patterns of immunodominance were identified whichare linked to structural features of the proteins (e.g. alpha helices or betasheets). The correlation between predicted and experimentally determinedepitopes differed strongly between the structural proteins. As many as 80%of the experimental epitopes in C but only less than 40% in prM/M and Ewere predicted by algorithms.In conclusion, there is evidence that protein specific structural featureshave a strong influence on epitope usage and on the predictability of suchepitopes by computer algorithms.REF O52A new lentiviral vector tool to evaluate measles virus escape frominfection- or vaccine-induced antibodiesCamille LEVY, Fouzia AMIRACHE, Caroline COSTA, CeciliaFRECHA, Claude P. MULLER, Hasan KWEDER, Robin BUCKLAND,François-Loïc COSSET, Els VERHOEYENCIRI, EVIR team, 69007, Lyon, FRANCELive measles virus (MV) vaccines are currently used worldwide and arehighly successful but MV still causes 4% of all child deaths worldwide.Importantly, circulating MVs give rize to MV strains mutated in differentepitopes of the MV envelope glycoproteins (gps), which is underlined byreoccuring MV outbreaks in the last years. Thus the risk exists that thevirus acquires multiple mutations allowing it to escape from vaccination.To evaluate this risk we engineered a lentiviral vector (LV) displayingat its surface the MV envelope gps H and F (H/F-LVs). These H/F-LVsretained the same target cell specificity as MV for human T, B and dendriticcells. Since these H/F-LVs encode for GFP, their neutralization by MVantibodies is detected by reduction of % of GFP+ target cells. Indeed,insertion of mutations in the Noose and NE major epitopes of the Hgp inthe H/F-LVs confirmed escape from NE and Noose specific antibodies butnot from antibodies in sera from MV vaccinated donors.Other emerging strains such as the MV-D genotypes are less sensitive toMV antibodies induced by vaccination. We attributed this to epitope shieldingby an extra glycosylation site, D416N, present in these MV D-cladestrains since introduction of this mutation into the H/F-LVs revealed lessneutralization by MV-specific antibodies. Finally, when this glycosylationsite was introduced into the H/F-LVs already mutated for the major epitopes,escape from MV-antibody neutralization was increased. Thus, thisvector tool might allow epitope-monitoring, invaluable in the surveillanceof measles epidemics.REF O53Design of Single Round Infection Alphaviruses: New Approaches ofVaccine DevelopmentIlya FROLOV 1 , Dal Young KIM 1 , Svetlana ATASHEVA 1 , EryuWANG 2 , Scott WEAVER 2 , Elena FROLOVA 11 University of Alabama at Birmingham, Birmingham, USA; 2 Universityof Texas Medical Branch, Galveston, USAThe Alphavirus genus in the Togaviridae family contains a number ofhuman and animal pathogens. The importance of alphaviruses has beenstrongly underappreciated; however, recent epidemics of chikungunyavirus has raised their profile. In spite of a continuous public health threat,to date no licensed vaccines have been developed to any alphavirus infections.The currently available experimental live vaccines and inactivatedviruses suffer from traditional draw backs, such as reactogenicity or lowefficiency and short lived immune response. We have applied an accumulatedknowledge about the mechanism of alphavirus replication and proteinfunction in virus host interactions to introduce a number of new approachesin designing attenuated variants. The artificially designed alphavirusesare constructed from genes derived from different, geographically isolatedviruses. They lack the important contributors to viral pathogenesis:proteins functioning in inhibition of the innate immune response, causeonly a single round infection in vivo and do not induce detectable diseaseeven in immunocompromized animals. Nevertheless, these mutants closelymimic natural viral infection in terms of RNA replication, productionof viral proteins and release of viral particles. Such alphaviruses alsoinduce a highly efficient, protective immune response. An additionalimportant characteristic of the recombinant viruses is their inability toreplicate in mosquito vectors. These new approaches are applicable for theconstruction of alphaviruses with a programmed, irreversibly attenuatedphenotype.REF O54Respiratory vaccination with live attenuated measles virus: studiestowards identification of the optimal site of vaccine deliveryRik DE SWART 1 , Rory D. DE VRIES 1 , Linda J. RENNICK 2 , GeertVAN AMERONGEN 1 , Stephen MCQUAID 3 , Selma YÜKSEL 1 ,R.Joyce VERBURGH 1 , Martin LUDLOW 2 , Albert D.M.E.OSTERHAUS 1 , W. Paul DUPREX 21 Erasmus MC, dept. Viroscience, Rotterdam, THE NETHERLANDS;2 Boston University, dept. Microbiology, Boston, USA; 3 Queen’s Universityof Belfast, Tissue Pathology, Belfast, NORTHERN IRELANDThe standard route of measles virus (MV) vaccination is subcutaneousinjection, which is far from the natural route of wild type MV transmission.Programs evaluating alternative vaccination routes have been hampered bya lack of knowledge about the primary cells that should be targeted. Theaim of our study was to determine whether MV vaccination via the respiratoryroute should target the upper or lower respiratory tract (LRT). Wegenerated a recombinant virus based on the Edmonston Zagreb (EZ) strain,expressing enhanced green fluorescent protein (EGFP) from an additionaltranscription unit in position 3 of the genome. The virus was grownin MRC 5 cells and formulated with the same stabilizers and excipientsused in the MV EZ vaccine produced by the Serum Institute of India.Four groups of twelve macaques were immunized with a dose of 10ˆ4TCID50 rMV EZ EGFP(3) via different routes of administration: injection,intra tracheal inoculation, intra nasal instillation or aerosol inhalation.In each group six animals were euthanized at early time points, whereasthe other six were followed up to assess immunogenicity. Infected cellswere detected in the muscle, nose and lungs, but systemic MV replicationwas virtually absent. Macrophages and dendritic cells were the predominanttarget cells in all cases. Animals vaccinated via the respiratory routehad the highest specific serum antibody when the virus was delivered tothe LRT. This study sheds new light on the tropism of live attenuatedMV vaccine, and identifies the LRT as the optimal target for respiratorydelivery.S60 Virologie, Vol 17, supplément 2, septembre 2013