Therefore, this review concentrates on recent reports highlighting the most studied antigens and adjuvants in pertinent examples of vaccines, including summaries of veterinary and experimental therapeutic cancer vaccines. Other nanoparticulate vaccines based on lipoplexes, niosomes, virus-like particles, solid lipid nanoparticles and nanoemulsions are selleck product not covered in this review. A key advantage of liposomes, archaeosomes and virosomes in general, and liposome-based delivery systems in particular, is their versatility and plasticity (see Table 1). Liposome composition and preparation can be chosen to achieve desired features such as

lipid composition, charge, size, size distribution, entrapment and location of antigens or adjuvants. Depending on the chemical properties, water-soluble compounds (proteins, peptides, nucleic acids, carbohydrates, haptens) are entrapped within the aqueous inner space, whereas lipophilic compounds (lipopeptides, antigens, adjuvants, linker molecules) are intercalated into the lipid bilayer and antigens can be attached to the liposome surface either by adsorption or stable

chemical linking [Torchilin, 2005; Watson et al. 2012]. Coformulations containing different types of antigens and adjuvants can be combined to tailor liposomal vaccines for individual applications (see Figure 2). Table 1. Characteristics of liposome, archaeosome, and virosome vaccines. Liposome-based antigens Liposome-mediated effects of antigen uptake, trafficking, processing and presentation As the majority of vaccines are administered by intramuscular or subcutaneous injection, liposome properties play a major role in local tissue distribution, retention, trafficking, uptake and processing by APCs. Earlier studies

showed clear size-dependent, but not unambiguous charge or lipid composition dependent effects at the injection site [Oussoren et al. 1997]. Newer studies with the cationic liposome formulation dimethyl dioctadecylammonium (DDA) plus trehalose dibehenate (TDB) (DDA/TDB, CAF01) showed no differences in liposome draining or antigen release from the injection site. However, differences in movement to regional lymph nodes (LNs) were noted [Henriksen-Lacey et al. 2010, 2011]. A cationic liposome pDNA vaccine of 500 nm and 140 Brefeldin_A nm size with encapsulated ovalbumin (OVA) encoding pDNA as antigen showed strongest retention at large vesicle size. Addition of poly(ethyleneglycol) (peg) coating resulted in enhanced lymphatic drainage, without improved immune response [Carstens et al. 2011]. Other pegylated DDA/TDB liposomes reduced the depot effect and altered the immune response, confirming these results [Kaur et al. 2012]. Badiee and colleagues evaluated liposomes of different sizes containing the surface glycoprotein of Leishmania (rgp63). Immunization with small liposomes induced a TH2 response, whereas large liposomes induced a TH1 response, higher interferon γ (IFNγ) levels and immunoglobulin IgG2a/IgG1 ratios [Badiee et al. 2012].