Two- and three-dimensional in vitro models for investigating TBEV-induced neuropathogenesis and discovering therapeutic drugs
Résumé
Tick-Borne Encephalitis Virus (TBEV), a member of the Flavivirus genus, is the major arbovirus of health interest in Central/Northern Europe and North-Eastern Asia. Although it is responsible for neurological manifestations that may cause permanent disability or death, there is currently no therapeutic treatment for the disease. Many neuropathological and drug discovery studies have been conducted using murine models but there is a lack of more physiologically relevant in vitro human models. In an attempt to develop such models, we used 2-dimensional cultures of neuronal/glial cells derived from human fetal neural progenitor cells (hNPCs) and previously showed that TBEV infection induces preferential neuronal tropism, astrogliosis and neuronal death, three major hallmarks of TBEV infection in the human brain. We further investigated the mechanisms of neuronal death using transcriptomic approaches and showed that genes involved in different types of cell death (pyroptosis and apoptosis) were upregulated, suggesting the occurrence of at least two different mechanisms leading to cell death in TBEV-infected human brain cells. To improve the physiological relevance of our in vitro models, we now developed human cerebral organoids from induced pluripotent stem cells and showed that TBEV infects and replicates in these 3-dimensional structures. In parallel, 2D TBEV-infected human neuronal/glial cells have also been used to develop an image-based screen for antiviral drugs. Selected drugs will next be tested for their efficiency and toxicity on 3D-cerebral organoids. We hope that, using these highly relevant models, we will select compounds with high probability to be efficient and non-toxic in the human brain.