Title : Development of universal influenza vaccine using M2e conjugated PLGA nanoparticle
Abstract:
To prevent next flu pandemics and to reduce the burden of seasonal flu infections, there is an urgent need to develop vaccines that are broadly protective against different influenza strains. In this regard we investigated polymeric nanoparticles as antigen carriers of a highly conserved epitope, the extracellular domain of M2 membrane protein (M2e) of the influenza type A virus, and compared immunogenicity from simple adsorption versus the chemical conjugations of M2e on to polymeric nanoparticles. We synthesized two types of nanoparticles from similar molecular weight polymers: i) PmNPs: nanoparticles made of poly (lactic-co-glycolic acid)–polyethylene glycol with maleimide linker, ii) and PNPs: nanoparticles made of methoxy-polyethylene glycol-poly (lactic-co-glycolic acid). PmNPs and PNPs were characterized by transmission electron microscopy and dynamic light scattering. We conjugated M2e on the surface of PmNPs, via maleimide-thiol rxn, whereas for PNPs, M2e was physically adsorbed at the same dose. We were immunized mice via intramuscular or intranasal routes on day 0 and 21 using M2e conjugated PmNPs or PNPs with soluble form of CpG as an adjuvant. Anti-M2e-specific IgG, IgG1 and IgG2a responses were determined in serum samples and lungs lavage after day 42 by ELISA. Cellular immune response was determined through cytokine analysis from splenocytes restimulation. Mice were challenged after day 42 with 3xLD50 of various strain of influenza virus and survival and weight loss were monitored daily. We synthesized PmNPs and PNPs of the comparable size (~100 nm). We found that covalently attached M2e at PmNPs with CpG had a more significant immune response and protection with challenge than from physically adsorbed M2e on PNPs. The intramuscular route was identified to be significantly better than the intranasal route in terms of anti-M2e immunoglobulin G (IgG), IgG1 and IgG2a, cellular immune response and protection with challenge. We found full protection in PmNP-M2e with CpG immunized mice against challenged influenza viruses such as A/California/04/2009 (H1N1pdm), A/Victoria/3/75 (H3N2) and A/PR/8/34 (H1N1). We equally found reduced lungs virus titers and histopathological signs at day 5 after challenge in PmNPs-M2e with CpG immunized mice in comparison to other groups. Based on these data, we are successfully demonstrated that the use of PmNPs-M2e with CpG formulation could lead to the development of a universal influenza vaccine.
