High immunogenicity of plant-produced candidate influenza vaccine based on the M2e peptide fused to flagellin

Abstract

The ectodomain of the conserved influenza matrix protein M2 (M2e) is a promising target for the development of a universal influenza vaccines. Immunogenicity of M2e could be enhanced by its fusion to bacterial flagellin, the ligand for Toll-like receptor 5. Previously we reported the transient expression in plants of a recombinant protein Flg-4M comprising flagellin fused to 4 tandem copies of the M2e. The use of self-replicating recombinant vector based on the potato virus X allowed expression of Flg-4M in Nicotiana benthaminana leaves at a very high level, up to about 1 mg/g of fresh leaf tissue. Intranasal immunization of mice with Flg-4M induced M2e-specific serum antibodies and provided protection against lethal challenge with different strains of influenza A virus. Here we show that immunization with Flg-4M not only generates a strong immune response, but also redirects the response from the carrier flagellin toward the M2e epitopes. Significant IgG response to M2e was also developed in bronchoalveolar lavages of immunized mice. Protective activity of Flg-4M upon lethal influenza challenge correlated with a decrease of virus titers in lungs relative to the control. Overall these data show the potential for the development of a plant-produced M2e-flagellin universal influenza vaccine.

Protein nanoparticle vaccine based on flagellin carrier fused to influenza conserved epitopes confers full protection against influenza A virus challenge

“…Tandem copies of M2e fused to TLR5 ligand flagellin were highly immunogenic in vivo , induced robust and long-lasting M2e-specific antibody responses and provided full protection against influenza A virus challenges (Huleatt et al, 2008; Mardanova et al, 2016; Stepanova et al, 2015; Wang et al, 2014a). In our study, the variable region of FliC was replaced with three types of weak antigens: four tandem copies of M2e, H1 HA2 domain and H3 HA2 domain (Fig 1).…”

Plant Virus Expression Vectors: A Powerhouse for Global Health

“…CPMV has been utilized extensively in antigenic presentation and full-length protein expression as part of a fusion protein that can undergo proteolytic cleavage to release the therapeutic protein, as well as in material science research, such as the formation of magnetic clusters and biosensors [ 63 , 64 , 65 , 66 ]. For example, Medicago, Inc. (Durham, NC, USA) has used the CPMV vector to generate virus-like particles (VLPs) carrying influenza virus HA antigens [ 67 ]. These VLPs protect against lethal viral challenge in animal models, and are now undergoing a Phase 2 clinical trial with over 250 volunteers.…”

Plant-Based Vaccine for Livestock: Key Points to Unleash Platform Translation in Developing Countries

“…To increase antigen immune stimulatory activity several successful and promising approaches have been used such as in plant production of virus-like particles (VLPs) [48], targeting of antigen to antigen presenting cells (APC) [49], fusion to mucosal adjuvants such as cholera toxin B subunits or E. coli heat labile enterotoxin B [50,51] or Lumazine synthase from Brucella spp. (BLS) [52,53], and recently to the Toll-like receptor (TLR) 5 agonist bacterial flagellin [54] a potent systemic and mucosal adjuvant. Medicago Inc's VLP technology applied to the pandemic flu vaccine has completed human clinical phase II and has obtained an emergency use authorization, while the quadrivalent seasonal influenza vaccines is currently in phase II [55].…”