Nanoparticle delivery of therapeutic vaccine for chronic hepatitis B

The focus of this dissertation is the evaluation of poly(D,L-lactic-co-glycolic acid) (PLGA) nanoparticles as a delivery system for therapeutic vaccines for hepatitis B virus (HBV) chronic infection. PLGA formulations of HBV core antigen with or without an immunomodulator, monophosphoryl lipid A, were characterized with respect to size, surface morphology, antigen loading and release. Immune response studies in mice in vivo showed that co-delivery of core antigen and MPLA in nanoparticles elicited a strong T helper type 1 response with interferon-gamma production by the activated T cells.; Pekin duck (Anas platyrhynchos) is an important preclinical animal model for hepatitis B. The duck MHC class II alpha (DRA) and invariant chain cDNA clones were sequenced and analyzed to facilitate the identification of antigen presenting cells (APCs). The deduced amino acid sequences of duck DRA and invariant chain cDNAs were homologous to human DRA and invariant chain, respectively. The transcripts of these two genes were found in the peripheral blood mononuclear cells (PBMCs) and in great abundance in the spleen.; Characterization of duck APCs was carried out with the adherent PBMCs. Duck monocytes/macrophages were identified based on their physical and functional properties. Analysis of the parameters for particle uptake by the adherent PBMCs revealed that they were able to internalize PLGA nanoparticles (∼600 nm) but not microparticles (∼18 mum). Lipopolysaccharide treatment promoted the phagocytosis of PLGA nanoparticles and production of oxidative metabolites.; A preliminary study was performed in ducks chronically infected with duck hepatitis B virus (DHBV) to determine whether the immune responses elicited by PLGA nanoparticulate vaccines could intervene in a natural viral infection. The results showed the reduction of viral load in the vaccinated ducks was not significantly different from the control. However, a duck hepatitis B core-specific IgY antibody response was induced, suggesting that immune tolerance to the viral antigen can be broken by immunization with the nanoparticle formulation.; This research highlights the potential of PLGA nanoparticles as a vaccine delivery system for the induction of antiviral immune response and their use in studying immune-mediated viral clearance in DHBV model.