Polysaccharides against viruses: immunostimulatory properties and the delivery of antiviral vaccines and drugs

Because viruses still represent a significant threat to human and animal health worldwide, the development of effective weapons against viral infections remains a top priority for the biopharmaceutical industry. This article reviews the dietary and pharmaceutical applications of polysaccharides (PS), first of all chitosan, in the prevention and treatment of viral diseases, focusing more particularly on solid or gel micro/nanoparticulate systems. The intrinsic antiviral activity of PS and their immunostimulatory effects, implemented in animal and human diets, are first surveyed. Then the review discusses the potential of PS-based particles as carriers of antiviral drugs and vaccines, with emphasis on the adjuvant potency of PS in solid vaccine formulations. The gap between the abundance of academic studies in this area and the lack of actual antiviral formulations dispensed to human patients is underlined, notwithstanding a number of branded products on the market.