Mobile DNAs as ecologically and evolutionarily independent units of life

Mobile DNAs drive the spread of virulence and antibiotic-resistance determinants across diverse bacterial lineages. However, they have been largely overlooked as therapeutic targets, limiting our ability to prevent the spread of their clinically relevant cargo genes. Mobile DNAs adopt various behavioural, evolutionary, and ecological strategies to enhance their diversification, transmission, and replicative fitness. They can do this even at the expense of their host bacterium. Here, we explore evidence that mobile DNAs are inherently selfish, and resemble endoparasites. Viewing them as such helps us to better understand their dynamics, and ultimately, could identify ways to limit their role in the spread of resistance. Shifting our therapeutic focus towards targeting the transmission of mobile DNAs could help us to manage the resistance crisis.