PLGA Nanospheres Loaded with Autoclaved Leishmania Major (ALM) and CpG-ODN: Preparation and in vitro Characterization

Objective(s) Several antigens, adjuvants and delivery systems have been evaluated for induction of protective immune responses against Leishmaniasis, but most of them have been inefficient. In this study, PLGA nanospheres as antigen delivery system CpG-ODN as an immunoadjuvant for increasing the immune responses against Autoclaved Leishmania major (ALM) were prepared and characterized. Materials and Methods PLGA nanospheres prepared by a double-emulsion (W/O/W) technique. The internal aqueous phase contained ALM and CpG-ODN, while the oily phase contained the solution of PLGA in dichloromethan and the external aqueous phase was PVA ۷.۵% (W/V) solution. Particulate characteristics were studied by scanning electron microscopy and particle size analysis. The encapsulation efficiency was determined by Lowry method for ALM and UV spectroscopy at ۲۶۰ nm for CpG-ODN. The release profiles of antigen and CpG-ODN from nanospheres evaluated for one week. Results Nanospheres were spherical in shape, having smooth surfaces. Mean diameters for blank and ALM + CpG-ODN loaded nanospheres recorded as ۳۰۲±۱۲۹ and ۳۰۰±۱۲۸ nm respectively. Also, the encapsulation efficiencies of ALM and CpG-ODN were ۷۱.۶±۸.۸ and ۴۹.۱±۲.۴%, respectively. Evaluation of the release profiles of ALM and CpG-ODN from nanospheres showed that ۴۴.۸±۰.۸% of ALM and ۲۹.۵±۰.۲% of CpG-ODN released from nanospheres in one week. Conclusion The prepared nanospheres with desirable size, encapsulation efficiency, and slow rate of release, had acceptable features for future in vivo studies.

Keywords:

Leishmania major , CpG-ODN , PLGA nanosphere , Vaccine