SLTRiP induces long lasting and protective T-cell memory response

Major developments have been made in the past many years to characterize and explore potential vaccine candidates that can induce host immune responses against parasite. These advances were based on the fact that the induction of host immune responses could effectively target parasite at different stages of its life cycle and thus, abrogate Plasmodium infections. The role of T-cells against malaria comes from initial studies on rodents showing these cells could inhibit parasite development during pre-erythrocytic stages. Since then, the importance of the cellular immune responses against malaria has been increasingly emphasized, especially for vaccine development against pre-erythrocytic stages. Previous work in our laboratory has confirmed that SLTRiP confers protection against the pre-erythrocytic stage of Plasmodium growth in rodents. Here we report that the protection is mainly due to cell mediated immune responses and PbSLTRiP specific cellular memory responses could be efficiently recalled in mice challenged with P. berghei parasites even after a year following immunization. Our results thereby, highlight the role of the T cell response involved in protection. Characterization of T-cells by intracellular cytokine staining (ICS) revealed that the induced T cells were polyfunctional and involved in secretion of pro-inflammatory cytokines which mediate anti-parasitic activity. The findings contribute to our understanding of the immunological mechanisms underlying the protective vaccines.