Immunogenicity of cysteine protease leishmania martiniquensis dna based vaccine in mice

Abstract

A DNA vaccine was developed containing a partial consensus cysteine protease B (cpb) gene (pcDNA_cpb) derived from autochthonous L. martiniquensis strains in Thailand. BALB/c mice were intramuscularly immunized three times in two-week intervals with humanized codon cpb plasmid DNA (pcDNA_cpb) or in combination with monoolein (MO) as adjuvant (pcDNA_cpb-MO). The analysis of immune response demonstrated that pcDNA_cpb and pcDNA_cpb-MO could stimulate immune responses. In addition, 3 weeks after L. martiniquensis promastigote challenge, vaccinated mice sera showed significantly increased production of Th1 response; IgG2a and IFN-g and reduced IL-10 levels than the vehicle control mice sera. IFN-g/IL10 ratio was significantly higher in both pcDNA_cpb and pcDNA_cpb-MO with significant differences from control groups indicating potentially protective immune responses in mice. Mice were potentially protected after three weeks of being challenged with L. martiniquensis promastigote , which was demonstrated by a significantly lower parasite burden in the livers and spleens of mice quantitated by qPCR and anti-LPG binding to amastigotes using an immunohistochemical method. Monoolein, as an adjuvant, produced a booster effect to enhance mice Th1 protective immunity. This is the first report of the potential protection of partial cysteine protease B DNA vaccine of L. martiniquensis in a mouse model.

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