DNA vaccination with a plasmid encoding LACK-TSA fusion against Leishmania major infection in BALB/c mice

ABSTRACT

Vaccination would be the most important strategy for the prevention and elimination of leishmaniasis.The aim of the present study was to compare the immune responses induced following DNA vaccinationwith LACK (Leishmania analogue of the receptor kinase C), TSA (Thiol-specific-antioxidant) genesalone or LACK-TSA fusion against cutaneous leishmaniasis (CL). Cellular and humoral immuneresponses were evaluated before and after challenge with Leishmania major (L. major). In addition,the mean lesion size was also measured from 3th week post-infection. All immunized mice showed apartial immunity characterized by higher interferon (IFN)-γ and Immunoglobulin G (IgG2a) levelscompared to control groups (p<0.05). IFN-γ/ Interleukin (IL)-4 and IgG2a/IgG1 ratios demonstratedthe highest IFN-γ and IgG2a levels in the group receiving LACK–TSA fusion. Mean lesion sizesreduced significantly in all immunized mice compared with control groups at 7th week post-infection(p<0.05). In addition, there was a significant reduction in mean lesion size of LACK-TSA andTSA groups than LACK group after challenge (p<0.05). In the present study, DNA immunizationpromoted Th1 immune response and confirmed the previous observations on immunogenicity ofLACK and TSA antigens against CL. Furthermore, this study demonstrated that a bivalent vaccinecan induce stronger immune responses and protection against infectious challenge with L. major.