Immunological evaluation of colonic delivered Hepatitis B surface antigen loaded TLR-4 agonist modified solid fat nanoparticles

• HBsAg entrapped nanoparticles containing MPLA were prepared.
• Prepared nanoparticles were characterized by various bio-physical methods.
• Colon as attractive site for nanoparticulate vaccine uptake was tested.
• Biological studies showed that improved and potent immune response was achieved by those nanoparticles.

Hepatitis B is one of the leading liver diseases and remains a major global health problem. Currently available vaccines provide protection but often results in weaker/minimal mucosal immunity. Thus the present study is devoted to the development and in-vivo exploration of the colonically delivered biomimetic nanoparticles which capably enhance humoral as well as cellular immune response. In present work, Hepatitis B surface antigen (HBsAg) entrapped nanoparticles containing Monophosphoryl lipid A (MPLA) (HB + L-NP) were prepared by solvent evaporation method and characterized for particle size (~ 210 nm), shape, zeta potential (− 24 mV ± 0.68), entrapment efficiency (58.45 ± 1.68%), in-vitro release and antigen integrity. Dose escalation study was done to confirm prophylactic immune response following defined doses of prepared nanoparticulate formulations with or without MPLA. Intramuscular administered alum based marketed HBsAg (Genevac B) was used as standard (10 μg) and were able to induce significant systemic (IgG) but remarkably low mucosal immune (IgA) response. Notably, HB + L-NP (0.5 ml–10 μg) induced strong systemic and robust mucosal immunity (510 and 470 mIU/ml respectively, p < 0.001) from which mucosal was more significant due to the involvement of Common Mucosal Immune System (CMIS). Likewise, significant cellular immune response was elicited by HB + L-NP through T-cell activation (mixed Th1 and Th2) as confirmed by significantly increased cytokines level (IL-2 and Interferon-γ) in spleen homogenates. This study supports that delivery of HBsAg to the colon may open new vista in designing oral vaccines later being one of most accepted route for potential vaccines in future.

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