One of the advanced lipid-based delivery systems is the solid–lipid nanoparticles (SLNs), which can be one of the alternative delivery system to electroporation. SLNs are basically composed of high-melting-point lipids that act as a solid core, covered by surfactants. The use of materials that are generally recognized as safe (i.e. triglycerides, partial glycerides, fatty acids, steroids) [35] leads to an advantageous toxicity profile [36].The SLN production by hot high-pressure homogenization is easy, and no organic solvents are required [37]. Scaling-up is standardized up to 50-kg batches [38], and steam sterilization is possible [39]. The excellent activity and superiority of DOTAP–cetyl palmitate–SLN were reproducible.

The positively charged SLN would bind to polyanionic DNA via electrostatic

force leading Epigenetics inhibitor to SLN–DNA complex that will protect DNA from interaction with small molecules in the environment and will be taken into cell by an endocytosis process [40]. An additional advantage of delivering vaccine candidates by nanoparticles is the potential to enhance their stability during transport, and this is critical in areas that lack reliable cold storage chain (2–8°C) [41]. Our previous results revealed that stable formulation of cSLN was able to protect pDNA in DNase I challenge assay and deliver it to the right immune cells for the proper immune response induction [22]. In this study, we generated a DNA vaccine encoding A2–CPA–CPB−CTE as a trifusion gene and compared the impact of DNA vaccine delivery to immune cells (e.g. physical/electroporation vs. chemical/cSLN formulation) on the development of protective immune response against an infectious Navitoclax purchase L. infantum challenge. The pcDNA–A2–CPA–CPB−CTE was formulated into cationic

lipid particles with nanometre Bay 11-7085 range (~240–250 nm). In our experimental system, the administration of pcDNA–A2–CPA–CPB−CTE in BALB/c mice elicited the induction of specific Th1 and Th2 clones, indicating a mixed immune response and the production of IFN-γ and IL-10, although IFN-γ was much higher than IL-10, especially in G2 using the cSLN formulation. However, a higher amount of IFN-γ was obtained in G1 immunized via electroporation in response to both rA2–rCPA–rCPB and F/T L. infantum antigens at 4 and 8 weeks after challenge. Although IFN-γ secretion at 8 weeks after challenge in G1 was higher than in G2, there were no significant differences in IFN-γ: IL-10 ratio between these two groups. Also, at 8 weeks after challenge, the IFN-γ: IL-10 ratio in splenocytes from mice immunized with pcDNA–A2–CPA–CPB−CTE (G1 and G2) stimulated with rA2–rCPA–rCPB was significantly higher than G3 (~28·25- and 26·5-fold; P < 0·01) and G4 (~8·69- and 8·154-fold; P < 0·01). The same result was obtained with splenocytes stimulated by F/T L. infantum antigen. So, we can conclude that these two delivery strategies elicit the same immune responses with efficient protection.