Development of leptospirosis vaccine by using the combination of LipL32 and Loa22 antigens and immunization in a heterologous prime-boost regimen

Abstract

Leptospirosis is a zoonotic disease caused by infection with pathogenic leptospira bacteria which comprise more than 250 serovars. This research aimed at developing vaccine by combining two antigens which are LipL32 and Loa22 as a vaccine and using a heterologous prime-boost regimen for immunization. The immunization was performed by priming with DNA vaccine encapsulated in chitosan (CS) nanoparticle which was used as a DNA delivery system and boosting with LipL32 and Loa22 recombinant proteins. CS was able to deliver DNA plasmid harboring lipL32 and loa22 and resulted in the expression of both genes in transfected HEK293T cell line. The study in mice showed that using the DNA vaccine encoding lipL32-loa22 genes in the same plasmid was better in stimulating antibody production than using co-administration of lipL32 and loa22 in different plasmids. Combination of two antigens for immunization provided neither synergistic nor antagonistic effect in induction of immune response including antibodies, lymphoproliferation, and cytokines production, compared with when using a single antigen. Therefore, combination of LipL32 and Loa22 and heterologous prime-boost regimen has potentials for further development which should be tested in an animal model of leptospirosis.