Bacillus thuringiensis is a bacterium increasingly used as microbial insecticide to fight lepidopteran larvae, a major crop pest. Recently, this bacterium has also been involved in food poisoning and systemic infections, affecting humans, wildlife and the environment indiscriminately. As part of the “One Health” concept, our project tackles the mechanism of virulence of this bacterium using insects, mice and human cell culture and combining medicine, immunology, cell biology, genetics and bioinformatics. It contributes to the topic “Assessment and detection of anthropogenic risks to human health”.