The role of LPD-nanoparticles containing recombinant major surface glycoprotein of Leishmania (rgp63) in protection against leishmaniasis in murine model

CONTEXT

Leishmaniasis is a major public health problem. Despite numerous attempts, yet there is no effective vaccine against human leishmaniasis, mainly due to a lack of an effective vaccine delivery system as well as adjuvant.

OBJECTIVE(S)

The aim of this study was to evaluate the ability of recombinant glycoprotein 63 (rgp63) as a model of Leishmania antigen, entrapped in liposome-polycation-DNA (LPD) complexes nanoparticles in inducing cell mediated immune (CMI) response and protecting against L. major in BALB/c mice.

MATERIALS AND METHODS

To this end, the abundant leishmania promastigote cell surface glycoprotein, gp63, was entrapped in nano-sized LPD (CpG) particles, (LPD (CpG)-rgp63), and BALB/c mice were immunized three times with either (LPD (CpG)-rgp63) or rgp63-CpG DNA or LPD (CpG) or free rgp63 and dextrose 5%. Various parameters including footpad thickness, splenic load of L. major parasites, rgp63-binding IgGs and also cytokine levels of rgp63-reactive T lymphocytes were then compared among different vaccinated animals.

RESULTS

The lowest number of parasites in spleen, the higher levels of IgG2a after challenge infection, the minimal footpad swelling and high level of IFN-γ secretion, all indicated that adjuvants and antigen-delivery systems are essential in modifying immune responses; as mice received LPD (CpG)-rgp63 induced immune response stronger than the other groups.

CONCLUSIONS

This study demonstrates that LPD nanoparticle is a promising and adaptable delivery system which could be modified towards specific vaccine targets to induce a more potent immune response in combination with rgp63.