Comparison of Protective Potency of DNA and Live Vaccines Expressing A2-CPA-CPB(-CTE) Antigens against Visceral Leishmaniasis in Syrian Hamster as Preliminary Study

BACKGROUND: Visceral leishmaniasis is the most severe form of leishmaniasis caused by Leishmania (L.) donovani complex. Drug-resistant strains have been developed as a consequence of the current chemotherapeutic interventions, which has increased the need for advanced preventive and therapeutic strategies. A2-CPA-CPB(-CTE)-recombinant strain of L. tarentolae, which is non-pathogenic to humans, was shown protective in live vaccine as well as its DNA vaccine counterpart in both murine and canine models. METHODS: We evaluated the effectiveness of these DNA and live vaccination harboring A2-CPA-CPB(-CTE) in protecting hamsters against L. infantum infection using prime-boost regimens, namely DNA/DNA and Live/Live (n=9 hamsters per group). Cationic solid lipid nanoparticles (cSLN) were utilized as an adjuvant for DNA priming and electroporation for boosting DNA. At different time points post-challenge, parasite burden and body weight as well as humoral immune responses were measured. RESULTS: Both immunization strategies partially protect hamsters against L. infantum challenge. This protective immunity is associated with remarkable decrease in parasite load in liver and spleen of vaccinated hamsters eight weeks after challenge compared to control group. CONCLUSION: Both test groups (DNA/DNA and Live/Live) elicited high levels of IgG2 and total IgG as humoral immune responses and lower level of parasite propagation in both liver and spleen.