Authors: P. Subbarayan, V.A. Dennis, C. Lee, E. Nyairo, S.R. Singh
Affilation: Alabama State University, United States
Pages: 348 - 351
Keywords: BSA, encapsulation
Respiratory Syncytial Virus (RSV) is one of the most common causes of severe respiratory tract infections affecting mainly elderly, infants and the immunocompromised worldwide. As yet, a safe and effective vaccine has not been developed to protect humans from RSV. An effective RSV vaccine requires the induction of mucosal immunity. But a major hurdle is the efficient induction of mucosal immune responses when immunogens are administered via the intranasal route. To achieve this, different strategies have been applied to meet this challenge. One such strategy is the development of polymeric nanoparticle delivery systems. Biodegradable poly (lactic-co-glycolic acid) is a copolymer nanoparticle synthesized by means of random ring-opening co-polymerization of two different monomers, the cyclic dimers (1,4-dioxane-2,5-diones) of glycolic acid and lactic acid. Chitosan, a bioadhesive polymer has been suggested to increase the membrane permeability when used as a nasal vaccine delivery agent. Chitosan is a biocompatible and biodegradable polysaccharide comprising, copolymers of glucosamine and N-acetylglocosamine and is available in a range of molecular weights. Chitosan based formulations can greatly improve the absorption of immunogens from the nasal cavity. The objectives of this study were as follows: 1) to first successfully encapsulate and characterize a model protein namely, bovine serum albumin (BSA) in combined PLGA-chitosan nanoparticles and 2) to similarly encapsulate and characterize an RSV multivalent protein in these nanoparticles to serve as a vaccine delivery system for RSV. BSA was encapsulated in PLGA-chitosan nanoparticle using the emulsion method. Encapsulation efficiency was evaluated by incubating the encapsulated protein for 16 h in sodium hydroxide and assaying for the free protein using the BCA assay as well as SDS gel electrophoresis. The encapsulation efficiency of BSA in PLGA-chitosan was determined to be > 89% as assessed by BCA. SDS gel electrophoresis revealed the release of the 67 kDa BSA protein. FTIR (Fourier Infrared Spectroscopy) was performed on nanoparticles, which indicated the presence of different functional groups. Various concentrations (0.75 to 1000 μg/mL) of combined PLGA-chitosan nanoparticle were subjected to cytotoxicity testing on mouse J774 macrophages using the MTT assay. The results show that nanoparticles were nontoxic at all concentration levels with cell viability greater than 95%. Our data shows the successful encapsulation and characterization of BSA in PLGA-chitosan nanoparticles. An RSV multivalent protein has been encapsulated in PLGA-chitosan nanoparticles and is currently being evaluated as a vaccine delivery system for RSV.