Hydroxyapatite as Nanoparticle-based Adjuvant: Leishmaniasis Vaccine Candidate

Leishmaniasis caused by Leishmania protozoa can be fatal if left untreated. An effective and safe human vaccine has still not been produced to eradicate the disease. Among vaccine development studies, dead vaccines are still known as the most reliable and cheapest method. The selection of an effective and safe adjuvant is important for killed vaccines. We have not found any studies in which hydroxyapatite particles were used as adjuvants in vaccine research against leishmaniasis. In this study, spherical Hydroxyapatite (HAp) nanoparticles with dimensions of 100nm were synthesized. Then, these particles were combined with autoclaved L. infantum antigens (ALA) to prepare vaccine formulations at different concentrations. To determine the immunogenicity of HAp, MTT cell viability analysis, nitric oxide (NO), and cytokine production abilities were investigated in vitro in J774 macrophage cells. According to the study results, it was determined that the cell viability level was 97 % at a concentration of 200 μg/ml, and there was a 10-fold increase in NO production and an approximately 8.5-fold increase in IL-12 cytokine production ability compared to the control group. Considering the study results and the non-toxic properties of HAp, we have shown that HAp can be used as an adjuvant in the development of new leishmania vaccines.