Immunoadjuvant capacity of flagellin and mannosamine-coated poly(anhydride) nanoparticles in oral vaccination

Bioadhesive poly(anhydride) nanoparticles coated with mannose (M-NP) or Salmonella Enteritidis derived flagellin (F-NP) were designed to be applied in oral vaccination strategies using ovalbumin (OVA) as antigen model. Nanoparticles formulations (OVA-M-NP, OVA-F-NP and control OVA-NP) were characterized and evaluated in BALB/c mice. OVA-M-NP and OVA-F-NP displayed a size of about 300-400 nm and were efficiently coated with the respective ligand, Systemic and mucosal immune responses reported after S.C. and oral administration, indicated that a single dose of OVA-M-NP and OVA-F-NP, elicited higher and balanced systemic specific antibody responses [IgG1 (Th2-response) and IgG2a (Th1-response)] compared to non-coated ones. In addition, oral immunization using OVA-M-NP or OVAF-NP was able to elicit a higher levels of intestinal secretory IgA compared to S.C. In summary, oral immunization by bioadhesive mannosylated or flagellin nanoparticles demonstrated strong long lasting systemic and mucosal immune responses than the respective non-conjugated vectors.