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Objective(s): Leishmaniasis is a complex parasitic disease that represents a major public health problem. Despite numerous attempts over the past decades, yet there is no effective vaccine against human leishmaniasis probably due to the lack of suitable adjuvants. In this study, a first generation liposomal-based Leishmania vaccine was developed using soluble Leishmania major antigens (SLA) and á, Ü-trehalose6, 6'-dibehenat (TDB) as an immunostimulatory adjuvant. In this liposome structure, the cationic lipid Dimethyldioctadecylammonium (DDA) provides intrinsic adjuvant activity and cholesterol was added as a membrane stabilizer. Liposomes containing SLA were prepared.Materials and Methods: BALB/c mice were subcutaneously (sc) immunized with Lip (DDA/TDB/CHOL)-SLA+, Lip (DDA/TDB)-SLA+, Lip (DDA)-SLA+, Lip (DDA/CHOL)-SLA+, SLA or Tris-HCl buffer. Immunization was done every two weeks for three weeks. The immunized mice were then challenged sc in the left footpad with 1×106 stationary phase L. major promastigotes (50 ìl), at 2 weeks after last booster injection.Results: mice immunized with any of the liposomal formulations containing SLA (Lip-SLA+), substantially increased footpad swelling and parasite loads of foot and spleen with no significant difference compared to Tris-HCl buffer or SLA alone. Lip-SLA+ formulations induced a mixed Th1/Th2 immune response characterized by IFN-ã and IL-4 production as well as high levels of IgG1 anti-Leishmania antibody. Conclusion: immunization with liposomes containing DDA and/or TDB in combination with SLA induces a mixed Th1/Th2 immune response and is not an appropriate strategy for preferential induction of a Th1 response and protection against leishmaniasis.

Objective(s): ISCOMATRIX vaccines have now been shown to induce strong antigen-specific cellular or humoral immune responses to a broad range of antigens of viral, bacterial, parasite or tumor. In the present study, we investigated the role of ISCOMATRIX charge in induction of a Th1 type of immune response and protection against Leishmania major infection in BALB/c mice. Materials and Methods: Positively and negatively charged ISCOMATRIX were prepared. BALB/C mice were immunized subcutaneously, three times with 2-week intervals, with different ISCOMATRIX formulations. Soluble Leishmania antigens (SLA) were mixed with ISCOMATRIX right before injection. The extent of protection and type of immune response were studied in different groups of mice. Results: The group of mice immunized with negatively charged ISCOMATRIX showed smaller footpad swelling upon challenge with L. major and the highest IgG2a production compared with positively charged one. The mice immunized with positively charged ISCOMATRIX showed the lowest splenic parasite burden compared to the other groups. Cytokine assay results indicated that the highest level of IFN- γ and IL-4 secretion was observed in the splenocytes of mice immunized with negatively charged ISCOMATRIX as compared to other groups. Conclusion: The results indicated that ISCOMATRIX formulations generate an immune response with mixed Th1/Th2 response that was not protective against challenge against L. major.

Abstract 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). However, using LZ is restricted due to various side effects such as uncontrolled lesion development. In the present research, the efficacy of cationic nanoliposomes containing CpG oligodeoxynucleotides (CpG ODN) as an improved adjuvant delivery system was studied to diminish the lesion development and infection course of L. major after inoculation into the mice. BALB/c mice were inoculated subcutaneously (SC) with L. major plus empty DSPC, DSPC (CpG ODN), DSPC (Non CpG ODN), empty DMPC, DMPC (CpG ODN), DMPC (Non CpG ODN) or HEPES buffer. The results showed that group of mice received DMPC (CpG ODN) nanoliposomes developed a significantly smaller lesion and showed minimum number of L. major in the spleen and draining lymph nodes. In addition, using DMPC (CpG ODN) liposomes resulted in a Th1 type of immune response with a preponderance of IgG2a isotype which is concurrent with the production of DMPC (CpG) induced IFN-γ in the spleen of the mice. Taken together, the results suggested that immune modulation using DMPC (CpG ODN) nanoliposomes might be a practical approach to improve the safety of LZ

Abstract 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). However, using LZ is restricted due to various side effects such as uncontrolled lesion development. In the present research, the efficacy of cationic nanoliposomes containing CpG oligodeoxynucleotides (CpG ODN) as an improved adjuvant delivery system was studied to diminish the lesion development and infection course of L. major after inoculation into the mice. BALB/c mice were inoculated subcutaneously (SC) with L. major plus empty DSPC, DSPC (CpG ODN), DSPC (Non CpG ODN), empty DMPC, DMPC (CpG ODN), DMPC (Non CpG ODN) or HEPES buffer. The results showed that group of mice received DMPC (CpG ODN) nanoliposomes developed a significantly smaller lesion and showed minimum number of L. major in the spleen and draining lymph nodes. In addition, using DMPC (CpG ODN) liposomes resulted in a Th1 type of immune response with a preponderance of IgG2a isotype which is concurrent with the production of DMPC (CpG) induced IFN-γ in the spleen of the mice. Taken together, the results suggested that immune modulation using DMPC (CpG ODN) nanoliposomes might be a practical approach to improve the safety of LZ