Here we investigate the immunogenicity of a combination adjuvant comprising emulsified fine particles (namely PELC) together with LD-indolicidin, a peptiomimetic stereoisomer of the bovine neutrophil peptide indolicidin. We demonstrated that intranasal vaccination with either PELC/LD-indolicidin or Alum enhances protective influenza-specific serological immunity in mice; however, the adjuvant potency of Alum was rather reduced when the mice vaccinated orally with formulated influenza vaccines. The information gathered from this study will enhance our effort in the formulation design as well as the optimization of alternative administration routes for prophylactic vaccines against emerging infectious diseases, in particular pandemic influenza.
