Background:
Leishmaniases are
neglected diseases caused by
infection with Leishmania parasites and there are no human
vaccines in use routinely. The purpose of this study was to examine the immunogenicity of ChimeraT, a novel synthetic
recombinant vaccine against
visceral leishmaniasis (VL), incorporated into a human-compatible
liposome formulation. Methods: BALB/c mice were immunized subcutaneously with ChimeraT/
liposome vaccine, ChimeraT/
saponin adjuvant, or ChimeraT/saline and immune responses examined in vitro and in vivo. Results: Immunization with the ChimeraT/
liposome formulation induced a polarized Th1-type response and significant protection against L. infantum
infection. ChimeraT/
liposome vaccine stimulated significantly high levels of
interferon (IFN)-γ,
interleukin (IL)-12, and
granulocyte macrophage-colony stimulating factor (
GM-CSF)
cytokines by both CD4 and CD8 T-cells, with correspondingly lower levels of
IL-4 and
IL-10 cytokines. Induced
antibodies were predominantly
IgG2a isotype, and homologous
antigen-stimulated spleen cells produced significant
nitrite as a proxy for
nitric oxide (NO). Furthermore, we examined a small number of treated VL patients and found higher levels of circulating anti-ChimeraT
protein IgG2 antibodies, compared to
IgG1 levels. Conclusions: Overall, the liposomal formulation of ChimeraT induced a protective Th1-type immune response and thus could be considered in future studies as a
vaccine candidate against human VL.