Adjuvanticity and protective immunity of Plasmodium yoelii nigeriensis blood-stage soluble antigens encapsulated in fusogenic liposome.

In our previous studies we established fusogenic properties of lipids isolated from edible yeast Saccharomyces cerevisiae (S. cerevisiae). We demonstrated that liposomes prepared from S. cerevisiae membrane lipid (saccharosome) can deliver encapsulated antigen into cytosol of the antigen presenting cells and elicit antigen specific cell mediated as well as humoral immune responses. In this study, we evaluated immunological behavior of saccharosome encapsulated cytosolic proteins (sAg) of Plasmodium yoelii nigeriensis in BALB/c mice. Immunization with antigen (sAg) encapsulated in saccharosome resulted in enhancement of CD4+ and CD8+ T cell populations and also up-regulated the expression of CD80 and CD86 molecules on the surface of antigen presenting cells. Further, immunization with saccharosome-encapsulated sAg-induced elevated levels of both IFN-gamma and IL-4 cytokines in the immunized mice when compared to egg PC liposome encapsulated sAg or its IFA emulsified form. Saccharosome-mediated immunization resulted in induction of high level of total antibody response with preponderance of IgG2a isotype as well. The data of this study suggest that saccharosome-based vehicle can emerge as an effective vaccine in imparting protection against various intracellular pathogens including Plasmodium yoelii nigeriensis.