Phage therapy, i.e. the use of bacteriophage viruses (or phages) to treat human bacterial infections, was discovered in the 1920s but has been eclipsed by the massive rise of antibiotics from the 1940s onward. In the context of the rise in anti-microbial resistance, there is a renewed interest in France in phagotherapy, which is not without encountering a certain number of obstacles and difficulties in its development. Indeed, phages are highly specific: each bacterial infection requires particular phages, making phage therapy a tailor-made medicine difficult to scale-up. However, for nearly fifteen years, a French start-up has been trying to industrially produce phage therapy and to make viruses emerge as drugs, which has never before been achieved. Based on a multi-sited ethnography within the start-up and with researchers, doctors, pharmacists and representatives of regulatory agencies, this communication proposes to question the material and regulatory conditions necessary for the industrial production of phages. By looking at the difficulties encountered by the firm in making phages an umpteenth antibiotic and in rendering the production of phages scalable, this contribution aims to highlight the disruptive nature of the phage, which as a living entity is not easily domesticated. This is evidenced by continuous adaptations and adjustments that the industrial process requires on a daily basis to the staff, their tasks, spaces and location.< Réduire