Gold nanoparticle-M2e conjugate coformulated with CpG induces protective immunity against influenza A virus

AIM: This study aimed to develop a novel influenza A vaccine by conjugating the highly conserved extracellular region of the matrix 2 protein (M2e) of influenza A virus to gold nanoparticles (AuNPs) and to test the vaccine in a mouse influenza challenge model. MATERIALS & METHODS: Citrate-reduced AuNPs (diameter: 12 nm) were synthesized, and characterized by transmission electron microscopy and dynamic light scattering. M2e was conjugated to AuNPs through thiol-gold interactions to form M2e-AuNP conjugates. Particle stability was confirmed by UV-visible spectra, and M2e conjugation was further characterized by x-ray photoelectron spectroscopy. Mice were immunized with M2e-AuNPs with or without CpG (cytosine-guanine rich oligonucleotide) as an adjuvant with appropriate control groups. Sera was collected and M2e-specific immunoglobulin (IgG) was measured, and immunized mice were challenged with PR8-H1N1 influenza virus. RESULTS: M2e-capped AuNPs could be lyophilized and stably resuspend