Antigen delivery by filamentous bacteriophage fd displaying an anti-DEC-205 single-chain variable fragment confers adjuvanticity by triggering a TLR9-mediated immune response.

Rossella Sartorius,Fausta Cuccaro,Carmelo Biondo,Maria Antonietta De Matteis,Valerio Costa,Maria Giovanna De Leo,Sabato D'Auria,Maria Trovato,Luciana D'Apice,Piergiuseppe De Berardinis,Alfredo Ciccodicola,Vincenzo Manuel Marzullo

doi:10.15252/emmm.201404525

Abstract

Filamentous bacteriophage fd particles delivering antigenic determinants via DEC-205 (fdsc-αDEC) represent a powerful delivery system that induces CD8+ T-cell responses even when administered in the absence of adjuvants or maturation stimuli for dendritic cells. In order to investigate the mechanisms of this activity, RNA-Sequencing of fd-pulsed dendritic cells was performed. A significant differential expression of genes involved in innate immunity, co-stimulation and cytokine production was observed. In agreement with these findings, we demonstrate that induction of proinflammatory cytokines and type I interferon by fdsc-αDEC was MYD88 mediated and TLR9 dependent. We also found that fdsc-αDEC is delivered into LAMP-1-positive compartments and co-localizes with TLR9. Thus, phage particles containing a single-strand DNA genome rich in CpG motifs delivered via DEC-205 are able to intercept and trigger the active TLR9 innate immune receptor into late endosome/lysosomes and to enhance the immunogenicity of the displayed antigenic determinants. These findings make fd bacteriophage a valuable tool for immunization without administering exogenous adjuvants.

Highlights

Filamentous bacteriophage fd particles delivering antigenic determinants via DEC-205 represent a powerful delivery system that induces CD8+ T-cell responses even when administered in the absence of adjuvants or maturation stimuli for dendritic cells
The fdOVA particles or the NLDC:pOVA (OVA257-264 peptide delivered in the same molar amount by NLDC145 monoclonal antibody (mAb)) induced a significantly lower antigenspecific OT-I CD8+ T-cell proliferative response (Fig 1B) and no or weaker IFN-c production (Fig 1C).The proliferative activity induced by the OVA257-264 antigenic determinant delivered by anti-DEC-205 is low in comparison with a previous report describing the proliferation of OT-I T cells stimulated by an anti-DEC-205 antibody carrying ovalbumin protein (Bonifaz et al, 2004), while in agreement with this report, we did not observe production of IFN-c by OT-I T cells stimulated with anti-DEC antibody delivering the OVA257-264 peptide (NLDC:pOVA, Fig 1B and C)
It has been described that antigen-conjugated antibodies targeting C-type lectin receptors such as DEC-205 that are expressed by dendritic cells (DCs) efficiently induce antigen-specific T-cell responses (Bonifaz et al, 2004)

Summary

Introduction

Filamentous bacteriophage fd particles delivering antigenic determinants via DEC-205 (fdsc-aDEC) represent a powerful delivery system that induces CD8+ T-cell responses even when administered in the absence of adjuvants or maturation stimuli for dendritic cells. A significant differential expression of genes involved in innate immunity, co-stimulation and cytokine production was observed In agreement with these findings, we demonstrate that induction of proinflammatory cytokines and type I interferon by fdsc-aDEC was MYD88 mediated and TLR9 dependent. Phage particles containing a single-strand DNA genome rich in CpG motifs delivered via DEC205 are able to intercept and trigger the active TLR9 innate immune receptor into late endosome/lysosomes and to enhance the immunogenicity of the displayed antigenic determinants. These findings make fd bacteriophage a valuable tool for immunization without administering exogenous adjuvants

Methods

Results

Conclusion