Ceramide biosynthesis is critical for establishment of the intracellular niche of Toxoplasma gondii

Toxoplasma gondii possesses sphingolipid synthesis capabilities and is equipped to salvage lipids from its host. The contribution of these two routes of lipid acquisition during parasite development is unclear. As part of a complete ceramide synthesis pathway, T. gondii expresses two serine palmitoyltransferases (TgSPT1 and TgSPT2) and a dihydroceramide desaturase. After deletion of these genes, we determine their role in parasite development in vitro and in vivo during acute and chronic infection. Detailed phenotyping through lipidomic approaches reveal a perturbed sphingolipidome in these mutants, characterized by a drastic reduction in ceramides and ceramide phosphoethanolamines but not sphingomyelins. Critically, parasites lacking TgSPT1 display decreased fitness, marked by reduced growth rates and a selective defect in rhoptry discharge in the form of secretory vesicles, causing an invasion defect. Disruption of de novo ceramide synthesis modestly affects acute infection in vivo but severely reduces cyst burden in the brain of chronically infected mice. [Display omitted] •De novo sphingolipid synthesis is active at the ER of Toxoplasma gondii•T. gondii scavenges sphingomyelins but synthesizes ceramide phosphoethanolamines•TgSPT1 is required for establishment of the intracellular niche during invasion•Defects in T. gondii sphingolipid synthesis affect chronic infection in vivo Toxoplasma gondii is known to salvage sphingolipids from its host but has retained a ceramide biosynthesis pathway. Nyonda et al. demonstrate that the parasite’s sphingolipidome differs from that of its host because of active synthesis, which is important for establishment of the intracellular niche in vitro and for chronic infection.