Immunization with M2e-Displaying T7 Bacteriophage Nanoparticles Protects against Influenza A Virus Challenge

Abstract

Considering the emergence of highly pathogenic influenza viruses and threat of worldwide pandemics, there is an urgent need to develop broadly-protective influenza vaccines. In this study, we demonstrate the potential of T7 bacteriophage-based nanoparticles with genetically fused ectodomain of influenza A virus M2 protein (T7-M2e) as a candidate universal flu vaccine. Immunization of mice with non-adjuvanted T7-M2e elicited M2e-specific serum antibody responses that were similar in magnitude to those elicited by M2e peptide administered in Freund’s adjuvant. Comparable IgG responses directed against T7 phage capsomers were induced following vaccination with wild type T7 or T7-M2e. T7-M2e immunization induced balanced amounts of IgG1 and IgG2a antibodies and these antibodies specifically recognized native M2 on the surface of influenza A virus-infected mammalian cells. The frequency of IFN-γ-secreting T cells induced by T7-M2e nanoparticles was comparable to those elicited by M2e peptide emulsified in Freund’s adjuvant. Emulsification of T7-M2e nanoparticles in Freund’s adjuvant, however, induced a significantly stronger T cell response. Furthermore, T7-M2e-immunized mice were protected against lethal challenge with an H1N1 or an H3N2 virus, implying the induction of hetero-subtypic immunity in our mouse model. T7-M2e-immunized mice displayed considerable weight loss and had significantly reduced viral load in their lungs compared to controls. We conclude that display of M2e on the surface of T7 phage nanoparticles offers an efficient and economical opportunity to induce cross-protective M2e-based immunity against influenza A.

A Novel Subnucleocapsid Nanoplatform for Mucosal Vaccination against Influenza Virus That Targets the Ectodomain of Matrix Protein 2

“…However, the reduction of viral load induced by N-3M2e was only partial compared to the reduction of viral load observed in mice immunized with iPR8. A partial reduc- tion of pulmonary viral load was also recorded in several studies evaluating the efficacy of M2e-based vaccine strategies, regardless of the antigen carrier and the dose of challenge virus (16,27,(31)(32)(33)(34)(35). In most cases, mice are efficiently protected against mortality even when the pulmonary viral load remains high.…”

Induction of Humoral and Cell-Mediated Immune Responses by Hepatitis B Virus Epitope Displayed on the Virus-Like Particles of Prawn Nodavirus

“…VLPs formed by the capsid proteins of viruses such as HBV (25,27,32) and human papillomavirus (33) and bacteriophages (8,34) have been widely used for displaying foreign epitopes for vaccine development. The carriers enhance the antigenicity of the fused epitopes (35)(36)(37), which are often found to be inefficient in eliciting immune responses.…”

Structural Basis for the Development of Avian Virus Capsids That Display Influenza Virus Proteins and Induce Protective Immunity

“…Serum antibody binding to native M2 and HA expressed on influenza virus-infected MDCK cells. Immune sera were assessed for specific binding to native tetrameric M2 protein expressed on influenza virusinfected MDCK cells as described previously (39). MDCK cells were cultured to near confluence in DMEM with 10% FBS in 96-well plates.…”