Highly Immunogenic Nanoparticles Based on a Fusion Protein Comprising the M2e of Influenza A Virus and a Lipopeptide.

Anna A Zykova,Nikolai V Ravin,Victor V Kuprianov,Liudmila M Tsybalova,Liudmila A Stepanova,Elena A Blokhina,Roman Y Kotlyarov

doi:10.3390/v12101133

Abstract

The highly conserved extracellular domain of the transmembrane protein M2 (M2e) of the influenza A virus is a promising target for the development of broad-spectrum vaccines. However, M2e is a poor immunogen by itself and must be linked to an appropriate carrier to induce an efficient immune response. In this study, we obtained recombinant mosaic proteins containing tandem copies of M2e fused to a lipopeptide from Neisseria meningitidis surface lipoprotein Ag473 and alpha-helical linkers and analyzed their immunogenicity. Six fusion proteins, comprising four or eight tandem copies of M2e flanked by alpha-helical linkers, lipopeptides, or a combination of both of these elements, were produced in Escherichia coli. The proteins, containing both alpha-helical linkers and lipopeptides at each side of M2e repeats, formed nanosized particles, but no particulate structures were observed in the absence of lipopeptides. Animal study results showed that proteins with lipopeptides induced strong M2e-specific antibody responses in the absence of external adjuvants compared to similar proteins without lipopeptides. Thus, the recombinant M2e-based proteins containing alpha-helical linkers and N. meningitidis lipopeptide sequences at the N- and C-termini of four or eight tandem copies of M2e peptide are promising vaccine candidates.

Highlights

Influenza A is a widely distributed respiratory infection of humans and animals
We demonstrated that fusion to the lipopeptide greatly enhances the immunogenicity of M2e, opening a new approach for the development of a “universal” influenza A vaccine
Since an increase in the number of M2e peptides in the recombinant protein enhances the immune response against M2e [11,25,26], we included four or eight tandem copies of M2e in the candidate vaccine proteins

Summary

Introduction

Influenza A is a widely distributed respiratory infection of humans and animals. A high variability of major surface proteins, hemagglutinin and neuraminidase, results in the frequent appearance of new epidemic strains and appropriate renewal of conventional influenza vaccines [1]. In view of this limitation, the development of “universal” recombinant vaccines based on conserved influenza viral proteins is an important task [2,3]. Anti-M2e antibodies do not neutralize the virus, M2e-based vaccines can confer both humoral- and cell-mediated immune responses directed towards infected cells exposing M2e on the surface.

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Discussion

Conclusion