Development and biological evaluation of pNIPAM-based nanogels as vaccine carriers

Abstract

“Smart” nanogels are an attractive tool for the development of new strategies of immunization in veterinary medicine. Here, we reported the synthesis and physicochemical characterization of thermoresponsive nanogels based on poly(N-isopropylacrylamide) (pNIPAM) and their in vitro, ex vivo and in vivo (mice model) performance. Smart nanogels of ca. 250 nm, with a transition temperature of 32 °C were obtained by precipitation polymerization. Assays to evaluate pNIPAM nanogels cytotoxicity were performed in different cell lines showing high biocompatibility (>70 %). The efficient internalization of the system was studied by confocal microscopy as well as flow cytometry. The ability to protect and deliver antigens was analyzed using the outer membrane lipoprotein A (OmlA), an important virulence factor of Actinobacillus pleuropneumoniae (App) cause of porcine pleuropneumonia. This lipoprotein was synthesized by recombinant technology and its technique was also described. The biodistribution of pNIPAM nanogels administered intranasally was performed in vivo and ex vivo through Pearl Imaging System, which showed that nanogels were kept mostly in the lungs during the evaluated time. Besides, the efficacy of the proposal nanogel-based vaccine was studied in vivo by measuring the antibody titers of BALB/c mice inoculated with OmlA encapsulated into pNIPAM nanogels compared to OmlA plus aluminum hydroxide adjuvant. The results proved the ability of nanogels to stimulate a humoral immune response. Therefore, we have demonstrated that pNIPAM nanogels can be used as an efficient platform for vaccine nanocarriers.