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. 2021 Dec 10;12:748387. doi: 10.3389/fimmu.2021.748387

Figure 1.

Figure 1

Adjusted study design. Following experimental infection of mice with S. mansoni cercariae and anti-parasitic treatment with racemic Praziquantel (PZQ), the susceptibility to reinfection with S. mansoni and schistosomiasis-driven pathology was assessed. Briefly, C57BL/6 wild-type and immunocompetent mice (8-10 weeks old to ensure the use of adult mice only) of 20-30g were separated into four experimental groups omitting long term infections without interspersed episodes of PZQ treatments i.e. groups A, B, C and D. Group A for an overall total of 1 infection and no PZQ treatment i.e. -/-/-/-/Sm, group B with a single pretreatment with PZQ and an overall total of 1 infection i.e. -/-/-/PZQ/Sm; group C for a single pretreatment with PZQ, an overall total of two infections intercalated by another treatment with PZQ i.e. -/PZQ/Sm/PZQ/Sm; group D for an overall total of three infections intercalated by two PZQ treatments i.e. Sm/PZQ/Sm/PZQ/Sm, as indicated on the illustration. Practically, mice were infected percutaneously with 35 S. mansoni cercariae (or cercariae water as Mock) and treated 6 weeks later with racemic PZQ (or carrier solution) by administration at 400mg/kg twice by oral gavage. One week following the end of anti-parasitic treatment with PZQ, mice were reinfected percutaneously with 35 S. mansoni cercariae (or cercariae water as Mock) i.e. at week 8. Animals were then treated with racemic PZQ (or carrier solution) 6 weeks later i.e. at week 14 by daily oral administration of PZQ at 400mg/kg by oral gavage for 7 days. Two weeks after the end of this second round of anti-parasitic treatment i.e. at week 17, all mice, including controls from group A and B, were reinfected percutaneously, with 35 S. mansoni cercariae. Animals were sacrificed in part at week 15 p.i. (time point 1 i.e. P1) or week 25 (time point 2, i.e. P2) for assessment of parasitological, immunological and pathological changes between groups. Specifically, biopsies of spleen, liver and blood were done for laboratory analyses of egg burdens, Antibody ELISA, Cytokine ELISA, Histology and Flow cytometry. Two independent experiments were conducted with 4-5 mice per group to be sacrificed at P1 (Group A &B, 4 mice; Group C, 5 mice; Group D, 4 mice) and 5-7 mice per group to be sacrificed at P2 (Group A, 5 mice; Group B, 4 mice; Group C, 6 mice; Group D, 7 mice). A total of 70 mice were used for this scheme.