Immunization of mice with soluble lysate of interferon gamma expressing Plasmodium berghei ANKA induces high IFN-γ production

Abstract

BackgroundEfforts in search of lasting malaria vaccine have led to the development of transgenic rodent malaria parasites. As a result, wild type Plasmodium berghei ANKA (WTPbA) has recently been transformed to express mouse interferon gamma (mIFN-γ). The immunomodulatory effect of this transgenic parasite on WTPbA infection has been demonstrated. However, the protective immune responses after repeated immunization with soluble lysate of this parasite has not been investigated.MethodsSoluble lysate of transgenic PbA (TPbA) was prepared and concentration of IFN-γ in lysate determined by ELISA. Four groups of 20 BALB/c mice each (two treatment groups and two control groups) were setup. Treatment Groups 1 and 2 were primed (at day 0) with lysate of TPbA containing 75 pg/ml IFN-γ and live TPbA parasites respectively. Infection in Group 2 mice was cured with Coartem™ at 450 mg/kg for 3 days. At day 14 post-priming, both groups were boosted twice at day 14 and day 28 with lysate of TPbA containing 75 pg/ml IFN-γ and 35 pg/ml IFN-γ respectively. Blood and spleen samples were collected at day 0, day 14, day 21 and day 28 for preparation of serum and cell cultures respectively. Serum IgG and cytokines (TNF-α and IFN-γ) levels in culture supernatant were measred by ELISA.Survivorship and parasitemia were daily monitored for 21 days. Data were statistically analyzed using ANOVA student’s t test. A p value of <0.05 was considered significant.ResultsAt day 28 post-priming, IFN-γ production in Group 1 was tenfold higher than in RBC control group (p = 0.070) There was significant difference in IFN-γ production among the groups at day 28 (p < 0.0001). TNF-α production in Group 1 mice increased fourfold in Group 2 mice from day 14 to day 28 post-immunization (p = 0.0005). There was no significant effect on serum IgG production. Mice in treatment groups survived 5 to 4 days longer compared to non-immunized group.ConclusionThe study has demonstrated that, repeated immunization with soluble lysate of TPbA induces Th 1 response leading to increased IFN-γ and TNF-γ production.

Functionally competent CD4+ T cells express high levels of T-bet in Plasmodium chabaudi infected young mice

“…5D & G) . To measure functional differences in the effector CD4 + T cell activation, we tested proliferation-inducing (IL-2) and protective (IL-10, IFN-γ and TNF) cytokine production during Plasmodium infection (29–31). Using intracellular cytokine staining, we observed much higher levels of IL-2 in the uninfected pups, which was reduced upon infection (Fig.…”

Model of severe malaria in young mice suggests unique response of CD4 T cells

“…The infected adult mice had significantly higher percentages and number of Teff Late (Figure 4D,G). To measure functional differences in the effector CD4 + T cell activation, we tested proliferation‐inducing (IL‐2) and protective (IL‐10, IFNγ, and TNF) cytokine production during Plasmodium infection 27–29 . Using intracellular cytokine staining and gating strategy as shown in (Figure 5A), we observed a distinct CD4 + T population of double IFNγ/IL‐10 producers that are well‐defined to be protective from severe immunopathology 12 .…”

“…To measure functional differences in the effector CD4 + T cell activation, we tested proliferation-inducing (IL-2) and protective (IL-10, IFNγ, and TNF) cytokine production during Plasmodium infection. [27][28][29] Using intracellular cytokine staining and gating strategy as shown in (Figure 5A), we observed a distinct CD4 + T population of double IFNγ/IL-10 producers that are well-defined to be protective from severe immunopathology. 12 While the IFNγ + and IFNγ/IL-10 double producers were lower in the infected pups compared to infected adults, they did not reach significance difference in both proportions and number (Figure 5B-D).…”

Plasticity in Interferon Responses Modulates T-Cell Immunity in Parasitic Infections: Periphery to Thymus

“…This suggests that IFN-γ production at different stages during infection could alter parasite survival and hence disease outcome. In P. berghei infection, IFN-γ along with TNF-α also plays a protective role by parasite removal activity [49]. The natural resistance to Plasmodium infection is reported in humans from tribes in Mali where resistance was correlated with increased [50], suggesting a protective role for IFN-γ against malaria.…”