Design of Self-Assembled Synthetic Nanorods for Vaccine Applications

Ximena Zottig^a,b,d, Mélanie Côté-Cyr^a,b,d, Soultan Al-Halifa^a,b,d, Margaryta Babych ^a,b, Denis Archambault^c,d and Steve Bourgault^a,b,d*

^aChemistry Department, Université du Québec à Montréal, Montreal, QC, Canada
^bQuebec Network for Research on Protein Function, Engineering and Applications PROTEO
^cDepartment of Biological Sciences, Université du Québec à Montréal, Montreal, QC, Canada
^dThe Swine and Poultry Infectious Diseases Research Centre, CRIPA

Proteinaceous nanostructures have emerged as a promising strategy to develop safe and efficient subunit vaccines. The ability of synthetic β-sheet self-assembling peptides to stabilize antigenic determinants and to potentiate the epitope-specific immune responses have highlighted their potential as an immunostimulating platform for antigen delivery. Nonetheless, the intrinsic polymorphism of the resulting cross-β fibrils, their length in themicroscale and their close structural similarity with pathological amyloids could limit their usage in vaccinology.In this study, we harnessed electrostatic capping motifs to control the self-assembly of a chimeric peptide comprising a 10-merβ-sheetsequence and a highly conserved epitope derived from the influenza A virus (M2e). Self-assembly led to the formation of 100 to 200 nm long uniform nanorods (NRs) displaying the M2e epitope on their surface. These cross-β assemblies differed from prototypical amyloid fibrils owing to low polydispersity, short lengths, non-binding to thioflavin T and Congo Red dyes, and incapacity to seed homologous amyloid assembly. M2e-NRs were efficiently uptaken by antigen presenting cells and the cross-β quaternary architecture activated the Toll-like receptor 2 and stimulated dendritic cells. Mice subcutaneous immunization revealed a robust M2e-specific IgG response, which was dependent on self-assembly into NRs. Upon intranasal immunization in combination with the polymeric adjuvant montanide gel, M2e-NRs conferred complete protection with absence of clinical signs against a lethal experimental infection with the H1N1 influenza A virus. These findings indicate that by acting as an immunostimulator and delivery system, synthetic peptide-based NRs constitute a versatile adjuvanted nanoplatform for the delivery of subunit vaccines.