Rapid activation of dormant type IV pili enables a dispersal–infection tradeoff in environments with fluctuating nutrients

to minimize exposure to phages during starvation while remaining poised for rapid reactivation. Importantly, T4P promote resistance to opsonization and phagocytosis by macrophages and neutrophils. Upon nutrient upshift, full T4P activity therefore supports dispersal and host colonization while conferring immune protection, revealing a fundamental dispersal-infection tradeoff at the host- microbe interface in fluctuating environments such as the lung and gut.