Improved Innate and Adaptive Immunostimulation by Genetically Modified HIV-1 Protein Expressing NYVAC Vectors

Esther D Quakkelaar,Beatriz Perdiguero,Karen V Kibler,Giuseppe Pantaleo,Bertram L Jacobs,Federica Sallusto,Anke Redeker,Alexandre Harari,Jim Tartaglia,Mariano Esteban,David M Koelle,Abdelali Filali-Mouhim,Jean-Philippe Goulet,Thomas Duhen,Nikki M Loof,Ferry Ossendorp,Elias K Haddad,Antonio Lanzavecchia,Rafick Pierre Sékaly ,Carmen Elena Gómez ,Paul P Heinen ,Stella Mccaughey ,Cornelis J.m Melief

doi:10.1371/journal.pone.0016819

Abstract

Attenuated poxviruses are safe and capable of expressing foreign antigens. Poxviruses are applied in veterinary vaccination and explored as candidate vaccines for humans. However, poxviruses express multiple genes encoding proteins that interfere with components of the innate and adaptive immune response. This manuscript describes two strategies aimed to improve the immunogenicity of the highly attenuated, host-range restricted poxvirus NYVAC: deletion of the viral gene encoding type-I interferon-binding protein and development of attenuated replication-competent NYVAC. We evaluated these newly generated NYVAC mutants, encoding HIV-1 env, gag, pol and nef, for their ability to stimulate HIV-specific CD8 T-cell responses in vitro from blood mononuclear cells of HIV-infected subjects. The new vectors were evaluated and compared to the parental NYVAC vector in dendritic cells (DCs), RNA expression arrays, HIV gag expression and cross-presentation assays in vitro. Deletion of type-I interferon-binding protein enhanced expression of interferon and interferon-induced genes in DCs, and increased maturation of infected DCs. Restoration of replication competence induced activation of pathways involving antigen processing and presentation. Also, replication-competent NYVAC showed increased Gag expression in infected cells, permitting enhanced cross-presentation to HIV-specific CD8 T cells and proliferation of HIV-specific memory CD8 T-cells in vitro. The recombinant NYVAC combining both modifications induced interferon-induced genes and genes involved in antigen processing and presentation, as well as increased Gag expression. This combined replication-competent NYVAC is a promising candidate for the next generation of HIV vaccines.

Highlights

Development of an effective HIV-1 vaccine inducing both broadly neutralizing antibodies and virus-specific T cells has the best chance to inhibit HIV-1 replication, infection and acquisition
This NYVAC-C-DB19R has been analyzed for its effect on monocyte-derived and conventional dendritic cells (DCs)
MoDCs did not produce IFN-a after infection with either virus. plasmacytoid DCs (pDCs) infected with both NYVAC-C or NYVAC-C-DB19R resulted in high IFN-a production (.400 pg/ml; data not shown)

Summary

Introduction

Development of an effective HIV-1 vaccine inducing both broadly neutralizing antibodies and virus-specific T cells has the best chance to inhibit HIV-1 replication, infection and acquisition. Despite its limited replication in most mammalian cell types, it provides a high level of gene expression and triggers strong immune responses when delivering foreign antigens in animals and human beings [17,18,21,23,24,25,26,27]. These beneficial effects have stimulated the use of the NYVAC vector for vaccination against HIV and other infectious diseases [15,28]. These genes are important in innate and adaptive immunity and have the potential to improve cellmediated immune responses

Methods

Results

Conclusion