Glucan Particles Are a Powerful Adjuvant for the HBsAg, Favoring Antiviral Immunity

The lack of vaccine adjuvants that are able to induce robust T cell responses fosters the search for more powerful options. Pathogen-like particles are a promising approach. The adjuvant activity of pathogen-like particles is highly influenced by size and surface composition. This study aimed to evaluate the adjuvant potential of two different beta-glucan-based particles, blend chitosan/beta-glucan particles (ChiGluPs), which are positively charged and have mean size of 1276 nm, and neutral yeast-derived glucan particles (GPs), with a mean size of 3 mu m. Additionally, chitosan particles (ChiPs) were used to understand the effect of beta-glucan addition (ChiGluPs). Mouse spleen cells responded through the production of either TNF-alpha or RANTES, following in vitro stimulation with particles containing either beta-glucan (ChiGluPs and GPs) or chitosan (ChiGluPs and ChiPs). Human monocytes responded to all particles through TNF-alpha secretion. Subcutaneous vaccination of mice with the hepatitis B surface antigen (HBsAg) showed increased serum IgG for all particles compared to HBsAg alone (435-, 4500-, or 2500-fold increase for either ChiPs, ChiGluPs, or GPs). Interestingly, only GPs elicited the secretion of HBsAg-specific Th1, Th2, Th9, Th17, Th22, and Treg-related cytokines. This study demonstrates, for the first time, that GPs can have a significant role against the hepatitis B virus by favoring antiviral immunity.