Bacteriophages (or phages) are viruses that have bacteria as their hosts. Discovered a century ago, and rapidly used as therapeutic agents to treat bacterial infections, they were nevertheless eclipsed by the massive rise of antibiotics from the 1940s onward. Faced with the major public health scourge of antimicrobial resistance, some scientists and physicians are attempting to rekindle and develop therapeutic phages, encountering considerable difficulties along the way. Indeed, phages are highly specific: each bacterial infection requires particular phages, making phage therapy a precision medicine. Based on a multi-sited ethnography conducted in France and Belgium with researchers, doctors, hospital staff, patients, and representatives of regulatory agencies, the aim will be to document and analyze how new knowledge communities are being built and how they develop regulatory strategies to make viruses emerge as drugs. Phage therapy poses a number of challenges because the way phages work is not easily adapted to the standard evaluation procedures defined in the EBM (particularly RCTs). The aim will be to show how scientific, regulatory and economic logics are articulated in the development of this innovation. Finally, we will show how phages, through their applications in human and animal health, but also their use in agriculture, make it possible to think about the development of another type of medicine and to develop a different narrative on human/microbial relations than that of a spectrum oscillating between war and peace.< Leer menos