Recombinant M2e outer membrane vesicle vaccines protect against lethal influenza A challenge in BALB/c mice

Abstract

Currently approved influenza vaccines predominantly protect through antibodies directed against the highly variable glycoprotein hemagglutinin (HA), necessitating annual redesign and formulation based on epidemiological prediction of predominant circulating strains. More conserved influenza protein sequences, such as the ectodomain of the influenza M2 protein, or M2e, show promise as a component of a universal influenza A vaccine, but require a Th1-biased immune response for activity. Recently, recombinant, bacterially derived outer membrane vesicles (OMVs) demonstrated potential as a platform to promote a Th1-biased immune response to subunit antigens. Here, we engineer three M2e-OMV vaccines and show that all elicit strong IgG titers, with high IgG2a:IgG1 ratios, in BALB/c mice. Additionally, the administration of one M2e-OMV construct containing tandem heterologous M2e peptides (M2e4xHet-OMV) resulted in 100% survival against lethal doses of the mouse-adapted H1N1 influenza strain PR8. Passive transfer of antibodies from M2e4xHet-OMV vaccinated mice to unvaccinated mice also resulted in 100% survival to challenge, indicating that protection is driven largely via antibody-mediated immunity. The potential mechanism through which M2e-OMVs initiated the immune response was explored and it was found that the constructs triggered TLR1/2, TLR4, and TLR5. Our data indicate that OMVs have potential as a platform for influenza A vaccine development due to their unique adjuvant profile and intrinsic pathogen-mimetic nature.

Consensus M2e peptide conjugated to gold nanoparticles confers protection against H1N1, H3N2 and H5N1 influenza A viruses

“…The IgG1 to IgG2a ratio was found to be 1.2, which is within the range of 0.33 to 2 observed in other studies. These studies have used different carriers for M2e and deliver the vaccines via different routes (intramuscular, intranasal, subcutaneous or microneedle patch) (Kim et al, 2013; Rappazzo et al, 2016; Wang et al, 2014; Wang et al, 2013). The intranasal vaccination also promoted local production of IgG in lungs and IgA antibodies in nasal and lung washes of mice.…”

“…However, a major challenge in developing a vaccine based on M2e is that M2 naturally occurs in very small numbers on the virus surface (about 16–20 molecules per virion) (Holsinger and Alams, 1991; Lamb et al, 1985) and is poorly immunogenic. To enhance the immunogenicity of M2e various approaches have been employed including fusion of M2e to different carriers such as hepatitis B virus core protein (Neirynck et al, 1999), bacterially-derived outer membrane vesicles (Rappazzo et al, 2016), virus-like particles (Kim et al, 2014; Wang et al, 2012), through attachment to flagellin domains (Wang et al, 2014) or elastin-like polypeptides (Ingrole et al, 2014), and use of nanoparticles with soluble antigens (Seth et al, 2015; Wibowo et al, 2014). …”

Interspecies Communication between Pathogens and Immune Cells via Bacterial Membrane Vesicles

“…This finding has been reported for many species of gram-negative bacteria including Pseudomonas aeruginosa, Escherichia coli, Neisseria meningitidis , and Haemophilus influenzae (Wispelwey et al, 1989; Gu and Tsai, 1991; Söderblom et al, 2005; Ellis et al, 2010). MVs produced by various bacterial species can also activate TLR2 or TLR5, two other surface PRRs that recognize bacterial lipoproteins and flagellin, respectively (Bergman et al, 2005; Durand et al, 2009; Ellis et al, 2010; Cecil et al, 2016; Rappazzo et al, 2016). In contrast, the response of TLR7, TLR8, and TLR9 to MV-associated nucleic acids appears to be weak or absent (Ellis et al, 2010; Cecil et al, 2016).…”

Protection against homo and hetero-subtypic influenza A virus by optimized M2e DNA vaccine

“…Influenza is caused by the influenza virus, an important human respiratory infectious disease, which causes 250,000-500,000 deaths worldwide every year [1]. In recent years, drug-resistant strains and new types of influenza are continuously emerging, causing the influenza epidemic to be a constant and serious issue [2,3].…”