Abstract
The development of recombinant influenza vaccines with broad spectrum protection is an important task. The combination of conservative viral antigens, such as M2e, the extracellular domain of the transmembrane protein M2, and conserved regions of the second subunit of hemagglutinin (HA), provides an opportunity for the development of universal influenza vaccines. Immunogenicity of the antigens could be enhanced by fusion to bacterial flagellin, the ligand for Toll-like receptor 5, acting as a powerful mucosal adjuvant. In this study, we report the transient expression in plants of a recombinant protein comprising flagellin of Salmonella typhimurium fused to the conserved region of the second subunit of HA (76–130 a.a.) of the first phylogenetic group of influenza A viruses and four tandem copies of the M2e peptide. The hybrid protein was expressed in Nicotiana benthamiana plants using the self-replicating potato virus X-based vector pEff up to 300 µg/g of fresh leaf tissue. The intranasal immunization of mice with purified fusion protein induced high levels of M2e-specific serum antibodies and provided protection against lethal challenge with influenza A virus strain A/Aichi/2/68(H3N2). Our results show that M2e and hemagglutinin-derived peptide can be used as important targets for the development of a plant-produced vaccine against influenza.
Highlights
Influenza is a widely distributed viral infection of humans and animals
Traditional influenza vaccines are strain–specific and have limited efficiency in the prevention of infections caused by newly emerging strains of influenza viruses [1]
The goal of this study was to develop a plant-produced candidate influenza vaccine based on the combination of two conserved influenza antigens (M2e and HA2) and to investigate the immune response and protective activity in an animal model
Summary
Influenza is a widely distributed viral infection of humans and animals. The development of recombinant influenza vaccines with a broad protection spectrum and short production time is an important task. Such universal vaccines are based on the use of conserved viral antigens [2,3,4]. The design of a candidate vaccine protein composed of two or more conserved target antigens that could induce different arms of immune response (antibodies with different modes of action, CD4+ and CD8+ T-lymphocytes etc) would boost the efficacy of such protein-based vaccines. The HA protein represents an attractive target for vaccine development because of its important roles in the early stages of virus infection.
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