Polymeric Nanoparticles Engineered as a Vaccine Adjuvant-Delivery System

Global immunization saves millions of human lives each year through using vaccines, which include whole microbe-based products and the subunit ones formulated with just the components of antigens able to stimulate immune system to establish specific immunity against diseases. Subunit vaccines show numerous advantages, such as defined components, high safety profile, and production without the use of dangerous pathogens, but also limited capacity in eliciting immunity due to the lack of other components than antigens, including the immunostimulatory elements of pathogen- associated molecular patterns which are able to activate the innate immunoreponses. Recently, nanoparticles (NPs) formulated with polymeric materials, such as poly(lactic- co-glycolic acid), viral proteins, chitosan, hyaluronic acid, and polystyrene, with some bearing intrinsic adjuvanticity, are widely employed as vaccine adjuvant-delivery sys- tems (VADSs) and show great potential in developing subunit vaccines. Particularly, the polymeric NPs engineered with functional materials possess many features, such as targeting delivery, lysosome escape, anti-damaging protection, and ability to guide immune reactions toward a Th1 (T helper type 1) and Th2 pathway, which are crucial for establishing humoral and cellular immunity. This chapter describes polymeric NP-based VADSs designed for developing subunit vaccines able to elicit Ag-specific immunity at both systemic and mucosal levels via different vaccination routes. cell line expression system [28]. The researchers demonstrated that mice vaccinated by intranasal prime followed by two sub-cheek boosts with VLPs adjuvanted with liposomes entrapping TLR3 ligand dsRNA were stimulated to secrete high titers of Abs against the Ags, with predominant IgG2c over IgG and produce a significantly increased germinal center B cells and T follicular cells, suggesting that the VLP-based VADS is superior for induction of a Th1-biased immune response, while prolonging lymph node germinal centers, T follicular cells, and generating neutralizing antibodies, and thus is rather suitable for making HIV vaccines [26].