Conclusion
The results demonstrated that liposomal PO CpG ODN could be used instead of PS CpG ODN to overcome the possible drawbacks.
Methods
Soluble Leishmania antigens (SLA) as a model antigen and distearoylphosphatidylcoline (DSPC) as a neutral lipid were employed to prepare liposomes. Susceptible BALB/c mice received buffer, SLA, Lip-SLA, Lip-SLA-PS CpG, Lip-SLA-PO CpG, SLA+PS CpG, or SLA+PO CpG subcutaneously 3 times with 3 weeks intervals and then were challenged with Leishmania major's live promastigotes. Blood and spleen samples were analyzed to determine the level and type of antibodies and cytokines. The number of live parasites in the spleen of immunized mice was determined. Moreover, the lesion size progress was assessed weekly by footpad swelling measurement.
Results
The results showed that mice immunized with Lip-SLA-PS CpG or Lip-SLA-PO CpG developed a significantly smaller footpad swelling, higher level of anti SLA IgG antibodies before and after challenge, and lower spleen parasite burden compared with the control groups. However, there was no significant difference between mice received Lip-SLA-PS CpG and those received Lip-SLA-PO CpG.