Institute of Animal Pathology

Host pathogen interaction of intracellular parasites

Multinucleated Theileria schizont infecting macrophage (parasite in green, nuclei in blue)

Single-celled parasites of the phylum Apicomplexa are important pathogens responsible for various human and animal diseases, including toxoplasmosis, cryptosporidiosis, and theileriosis. In our group, we are interested in the molecular mechanisms as to how these intracellular parasites interact with their host cell and cause disease. In the lab we focus on the zoonotic parasites Toxoplasma gondii, Cryptosporidium parvum, as well as the tick-transmitted pathogens Theileria annulata and Theileria parva. A better understanding of the molecular processes involved in parasite-host interaction may enable the development of novel therapeutics that reduce the devastating effects of these pathogens.

Cryptosporidiosis is a debilitating diarrheal disease of humans affecting mostly children and immunosuppressed individuals. Cryptosporidium parasites are a leading diarrheal pathogen in children, resulting in a substantial child mortality in the Global South. Cryptosporidium parasites are also the leading cause of diarrhea in calves in Switzerland. To survive in the host cell, Cryptosporidium parasites have established a unique niche for replication: intracellularly in the enterocyte but extracytoplasmic.

Theileria dividing — Continuously proliferating Theileria schizont-infected macrophages (parasite schizont in green). Huber et al. 2018 Cellular Microbiology

Theileriosis is a disease of cattle with a high socio-economic impact in sub-Saharan Africa and Southern Asia. Theileria parasites are widely recognized as the only eukaryotic pathogen able to entirely transform its host. Its transformative capacity is believed to be enabled by the interference with multiple host signaling pathways, thereby turning host cells into a proliferative and immortalized, cancer-like state. We are particularly interested in identifying parasite virulence effectors responsible for this transformation, and to better understand their mode of action.

For our research we also employ the highly amenable model apicomplexan Toxoplasma gondii, a widespread parasite of animals that causes zoonotic infection in humans. A quarter of the world’s human population is life-long infected with the parasite, which can lead to a variety of severe clinical outcomes such as encephalitis and congenital toxoplasmosis during pregnancy.