Modeling Toxoplasma gondii-gut early interactions using a human microphysiological system.

Oral transmission of parasites via environmentally resistant cyst stages in contaminated food or water is a common route of human infection, but there are no effective vaccines available for any enteric parasitic infection. Our knowledge of parasite cyst stage conversion and interaction with the intestinal tract is limited. Here, we investigate infection dynamics of Toxoplasma gondii cyst-stage in murine jejunum and human intestinal microphysiological systems. We focus on parasite ingress, replication, and conversion of the cyst stage to the rapidly replicating dissemination stage. In vivo bioluminescent imaging of mice fed cysts revealed spots of infection throughout the jejunum and ileum, which were selected for further analyses. Immunostaining showed parasite migration and replication predominantly in the stroma, with minimal replication in enterocytes. We recapitulated bradyzoite infection in human intestinal microphysiological systems and showed stage conversation and migration through collagen. This integrated approach elucidates complex host-parasite interactions, highlighting the value of microphysiological systems in advancing understanding and identifying potential therapeutics.