Because of the success of germ theory, developed first by Pasteur and then by Koch, our relations with microbes are most often not only presented, but also considered and analyzed through warlike metaphors. Eradicating, fighting, rejecting viruses are the conditions to maintain or restore the body integrity. Biosecurity policies, plans for eradication or preparedness for epidemics are thus striking examples of the political manifestation of the scientific knowledge produced on viruses.While the idea that bacteria can be grasp as something other than dangerous pathogens is becoming increasingly widespread, in particular through emphasis on microbiota work in recent years, viruses continue to suffer from a certain form of ignorance which limits them to the role of mortal and disruptive entities. However, viruses perform many functions, and are the most widely represented biological entities on earth, of which only a tiny fraction represents a threat to the human species. Based partly on the existing work in life sciences, partly on ethnographic data from my research on HIV clinical trials in sub-Saharan Africa, I propose to show how the interactions between humans and viruses entangle different scales and enact particular ways of belonging, and are in fact most often seized in terms of coevolution and coexistence. Taking three specific examples, smallpox, human endogenous retroviruses, and HIV, it is then possible to think, with Donna Haraway, of viruses as companion species (2008). Far from the hygienic framings, this paper presents a way to think our “becoming with” viruses.< Réduire