Liposomes containing the imiquimod adjuvant as a vaccine in the cutaneous leishmaniasis model

Objective(s): Attempts to produce vaccines for leishmaniasis need adjuvants to trigger the kind of immunereaction required for protection. In this study, we examined the properties of the TLR7 agonist imiquimod,a vaccine adjuvant, making use of a live model of infection where the immune reactions could be identifiedprior to and following the challenge of infection.Materials and Methods: The liposomes of EPC containing the imiquimod adjuvant were prepared andcharacterized for protein concentration, surface charge, and particle size. Vaccination was done using thesoluble Leishmania antigen (SLA) as a first-generation vaccine model in the liposomal state to vaccinateBALB/c mice against the challenge of leishmania major. BALB/c mice were vaccinated subcutaneously, threetimes at a two-week interval. Parasite burden, footpad swelling, IgG isotype, as well as the level of IL-4 andIFN-γ were assessed as the protection criteria.Results: The group of mice vaccinated by Lip+Imiquimod+SLA demonstrated a lower amount of footpadswelling and parasite burden than the buffer group. In addition, the highest level of IFN-γ and the lowestlevel of IL-4 production was noticed in the splenocytes of the mice vaccinated with the formulation ofLip+Imiquimod+SLA.Conclusion: These results imply that imiquimod added to the formulation of liposomes is able to modulatethe immune reaction of the BALB/c mice vaccinated preferably to a Th1 reaction rather than a Th2 reactionwhich can also lead to partial protection against the challenge of Leishmania.