Vaccination with Live Attenuated L. Major and TLR4 Agonist Promotes CXCL-10 against BALB/c mice

Background and Objectives: Leishmaniasis is a skin disease caused by different species of Leishmania. To date, no effective vaccine has been developed to prevent cutaneous leishmaniasis. One of the most effective vaccination methods against cutaneous leishmaniasis is leishmanization with attenuated L. major parasites. In previous studies, the use of some of the TLRs agonist along with Leishmania antigens has led to a protective immune response against leishmaniasis. This study was designed to evaluate the immunological of leishmanization with live attenuated L. major and TLR4 agonist in BALB/c mice. To evaluate the efficacy of vaccination with live attenuated L. major and TLR4 agonist in protection against L. major infection. Methods: Attenuated L. major (MRHO/IR/75/ER) was prepared by continuous sub-culturing (21 times) of the parasite. Sixty 4- to 6-week-old female mice including 60 BALB/c were assigned into 6 groups. BALB/c mice were divided into 6 groups (G1 to G6), where, G1 mice were the control group with no injection, G2 mice were inoculated with wild-type L. major promastigotes, G3 mice were inoculated with attenuated L. major, G4 mice were inoculated with TLR4 agonist, G5 mice were inoculated with wild-type L. major promastigotes along with TLR4 agonist, and G6 mice were inoculated with attenuated L. major promastigotes and TLR4 agonist. Forty-five days post injection, 5 mice were euthanized in each group. The levels of cxcl 10 chemokine in serum of mice was evaluated using cytometric bead-based assay. The chemokine level of cxcl 10 was specified via Flow Cytometry. Results: BALB/c mice which received the wild-type of parasite had the lowest level of cxcl 10 production. Vaccinated mice with a TLR4 agonist or attenuated L. major plus TLR4 agonist produced the highest levels of cxcl 10. Conclusion: Vaccination with the attenuated L. major along with TLR4 agonist promotes a Th1-mediated immune response which leads to the protection of BALB/c mice against L.major infection