Combination of M2e peptide with stalk HA epitopes of influenza A virus enhances protective properties of recombinant vaccine

Abstract

BackgroundInfluenza infection could be more effectively controlled if a multi-purpose vaccine with the ability to induce responses against most, or all, influenza A subtypes could be generated. Conserved viral proteins are a promising basis for the creation of a broadly protective vaccine. In the present study, the immunogenicity and protective properties of three recombinant proteins (vaccine candidates), comprising conserved viral proteins fused with bacterial flagellin, were compared.MethodsBalb/c mice were immunized intranasally with recombinant proteins comprising either one viral protein (the ectodomain of the M2 protein, ‘M2e’) or two viral proteins (M2e and the hemagglutinin second subunit ‘HA2’ epitope) genetically fused with flagellin. Further, two different consensus variants of HA2 were used. Therefore, three experimental positives were used in addition to the negative control (Flg-his). The mucosal, humoral, and T-cell immune responses to these constructs were evaluated.ResultWe have demonstrated that insertion of the HA2 consensus polypeptide (aa 76–130), derived from either the first (HA2-1) or second (HA2-2) virus phylogenetic group, into the recombinant Flg4M2e protein significantly enhanced its immunogenicity and protective properties. Intranasal administration of the vaccine candidates (Flg-HA2-2-4M2e or Flg-HA2-1-4M2e) induced considerable mucosal and systemic responses directed at both the M2e-protein and, in general, the influenza A virus. However, the immune response elicited by the Flg-HA2-1-4M2e protein was weaker than the one generated by Flg-HA2-2-4M2e. These recombinant proteins containing both viral peptides provide complete protection from lethal challenge with various influenza viruses: A/H3N2; A/H2N2; and A/H5N1.ConclusionThis study demonstrates that the intranasal administration of Flg-HA2-2-4M2e recombinant protein induces a strong immune response which provides broad protection against various influenza viruses. This construct is therefore a strong candidate for development as a universal vaccine.

Universal anti-influenza vaccines based on viral HA2 and M2e antigens

“…The first attempts to enhance the immunogenicity of HA2 gp utilized the carriers of different origins. As carries were frequently used Keyhole limpet hemocyanin KLH (Wang et al, 2010;Staneková et al, 2011;Janulíková et al, 2012;, flagellin from the Salmonella typhimurium vaccine strain (Arnon, 2006;Ben-Yedida and Arnon, 2007;Stepanova et al, 2018), nanoparticles (Kanekiyo et al, 2013;Yassine et al, 2015), or virus-like particles (VLP) (Kang et al, 2012;Chen et al, 2015). These vectors enable to present antigen in many copies, resulting in increased robustness of specific immune response.…”

“…One group of authors combined M2e and HA2 (aa 76-130) inserted into the full-length flagellin (Flg) from Salmonella typhimurium (Flg). Such vaccine administered subcutaneously to mice greatly increased antigen-specific T-cell response and provided full protection from lethal challenge with A/ H3N2 and A/H7N9 (Stepanova et al, 2018). Alternatively, these authors inserted HA2 polypeptide (aa76-130) into the recombinant Flg4M2e protein.…”

“…Alternatively, these authors inserted HA2 polypeptide (aa76-130) into the recombinant Flg4M2e protein. Intranasal immunization of BALB/c mice with this protein considerably induced mucosal and systemic responses directed against both proteins with resulting antiviral effect and complete protection from lethal challenge with influenza viruses A/H3N2, A/H2N2, and A/H5N1 (Tsybalova et al, 2018). Another research team developed an inactivated influenza virus with M2e epitope (aa 2-16) inserted into the Ca2 antigenic site of PR8 HA.…”

“…Another group of vaccines is targeted against internal proteins, matrix protein 1 (M1) or nucleoprotein (NP), inducing the cross-protection mediated by antigen-specific T-cells (Sridhar et al, 2013;Epstein, 2018). In order to stimulate both virus-specific T-cell immunity and protective antibody response, some vaccines contain combination of internal proteins (NP, M1) with HA2 domain or M2 ectodomain (M2e), utilizing different ways of antigen presentation (Heinen et al, 2002;Stepanova et al, 2018;Tsybalova et al, 2018;Sun et al, 2019).…”

Features of immune response against influenza infection in animals vaccinated with recombinant cross-protective vaccine

“…При этом они стимулируют врожден- ный иммунитет [21]. McKinstry K. и другие авторы показали, что в отсутствии В и CD8 + клеток защита осуществляется CD4 + Т-клетками памяти и сильно зависит от IFNγ [17,23,26]. В нашем опыте иммунизация кандидатной вакциной приводила к образованию специфических CD4 + Т-клеток памяти, как к М2е пептиду, так и к НА2 (аа76-130).…”