C3 Role of immunity-related GTPases (IRGs) of wild rodents for maintaining virulent T. gondii genotypes in nature (Seeber/Klotz)

Research Group: Parasitology unit of the Robert Koch-Institute
Address: Robert Koch-Institute

Division 16, Mycotic and Parasitic Agents and Mycobacteria
Nordufer 20
13353 Berlin

Supervisors: Professor Frank Seeber / Dr. Christian Klotz
Doctoral Researcher:     Francesca Torelli

Project Description

Wild rodents are important carriers of zoonotic pathogens such as Giardia spp. and T. gondii. The life cycle of T. gondii involves cats as definitive host and mainly small rodents as transmission host. Non-laboratory wild mice (Mus sp.) are resistant to infection with highly virulent (type I) T. gondii strains due to a polymorphic Immunity-Related GTPases (IRG) genotype (in particular IRGb2-b1), which resists vacuolar lysis and thus subsequent parasite death. However, wild rodents like Microtus sp. and Apodemus sp. rather than Mus sp. constitute the majority of cat prey in Europe. Therefore, we hypothesize that these wild rodents are a reservoir for virulent T. gondii genotypes due to a "resistant" IRGb2-b1 phenotype.

A key approach in the framework of this project will build upon the recent possibility to establish murine stem cell-derived intestinal organoids (IOs). This technique will be applied to generate such IOs from various wild rodents. The entry point for infection is the small intestine but the role of IRGs in the gut during T. gondii infection is unknown. Thus, IOs can serve as a unique in vitro-model for the early infection events to study innate immune responses in this organ. They also serve as a permanent source for genetic and transcriptomic experiments.

Main experimental approaches to test the hypotheses are:

  • Cloning of resistance-determining IRGb2-b1 of wild rodents and their expression in IFNγ-responsive cells to determine their resistance phenotype upon infection with virulent T. gondii.
  • Establishment of intestinal organoids from various mice & wild rodents.
  • Comparative analyses of early infection events of different T. gondii strains and stages in the established IOs (e.g., by life cell imaging, transcriptomics).
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