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.

The role of liposome-protamine-DNA nanoparticles containing CpG oligodeoxynucleotides in the course of infection induced by Leishmania major in BALB/c mice.

An inoculation of virulent Leishmania major is known as leishmanization (LZ) which is proven to be the most effective control measure against cutaneous leishmaniasis (CL) and mimic natural infection. However, use of LZ is restricted due to various reasons such as development of uncontrolled lesion. In the present study, the efficacy of coadminstration of live L. major with liposome-protamine-DNA nanoparticles (LPD) containing immunostimulatory CpG oligodeoxynucleotides (CpG ODN) which is an improved adjuvant delivery system is examined to check Leishmania pathology and immune response generated. BALB/c mice were inoculated subcutaneously (SC) with L. major plus LPD (CpG), CpG ODN or PBS buffer. The results showed that group of mice received LPD nanoparticles developed a significantly smaller lesion and the mice in this group showed minimum number of L. major in the spleen and lymph nodes. In addition, using LPD (CpG) resulted in a Th1 type of immune response with a preponderance of IgG2a isotype which is concurrent with the production of LPD induced IFN-γ in the spleen of the mice. Taken together, the results suggested that immune modulation using LPD nanoparticles might be a practical approach to improve the safety of LZ.

Cationic liposomes containing soluble Leishmania antigens (SLA) plus CpG ODNs induce protection against murine model of leishmaniasis.

Development of an effective vaccine against leishmaniasis is possible due to the fact that individuals cured from cutaneous leishmaniasis (CL) are protected from further infection. First generation Leishmania vaccines consisting of whole killed parasites reached to phase 3 clinical trials but failed to show enough efficacies mainly due to the lack of an appropriate adjuvant. In this study, an efficient liposomal protein-based vaccine against Leishmania major infection was developed using soluble Leishmania antigens (SLA) as a first generation vaccine and cytidine phosphate guanosine oligodeoxynucleotides (CpG ODNs) as an immunostimulatory adjuvant. 1, 2-Dioleoyl-3-trimethylammonium-propane was used as a cationic lipid to prepare the liposomes due to its intrinsic adjuvanticity. BALB/c mice were immunized subcutaneously (SC), three times in 2-week intervals, with Lip-SLA-CpG, Lip-SLA, SLA + CpG, SLA, or HEPES buffer. As criteria for protection, footpad swelling at the site of challenge and spleen parasite loads were assessed, and the immune responses were evaluated by determination of IFN-γ and IL-4 levels of cultured splenocytes, and IgG subtypes. The group of mice that received Lip-SLA-CpG showed a significantly smaller footpad swelling, lower spleen parasite burden, higher IgG2a antibody, and lower IL-4 level compared to the control groups. It is concluded that cationic liposomes containing SLA and CpG ODNs are appropriate to induce Th1 type of immune response and protection against leishmaniasis.

Induction of protection against leishmaniasis in susceptible BALB/c mice using simple DOTAP cationic nanoliposomes containing soluble Leishmania antigen (SLA).

A suitable adjuvant and delivery system are needed to develop an effective vaccine against leishmaniasis. To induce a Th1 type of response and protection in BALB/c mice against Leishmania major infection, 1,2-dioleoyl-3-trimethylammonium-propane (DOTAP) nanoliposomes bearing an intrinsic adjuvanticity, were used as an antigen delivery system and immunoadjuvant for soluble Leishmania antigens (SLA). DOTAP liposomes containing different concentrations of SLA were prepared by using lipid film method followed by sonication. The prepared vesicles showed a diameter of about 100nm, a positive zeta potential and approximately 70% encapsulation efficiency of SLA. BALB/c mice were immunized subcutaneously (SC), three times in a 3-week interval with different concentrations of liposomal SLA (12.5, 25, and 50µg of SLA/50µl/mice), free SLA and as well as free liposome. The group of mice received 50µg of SLA in DOTAP-nanoliposomes showed a significantly (p<0.001) smaller footpad swelling and the lowest spleen and footpad parasite burden after the challenge. This group also showed the highest IFN-γ production compared to the other groups, lower IL-4 level and higher IgG2a antibody titer. Taken together, the results indicated that simple DOTAP nanoliposome containing 1µg/µl SLA are appropriate delivery systems to induce a Th1 type of immune response and protection against L. major infection in BALB/c mice.