From host to population: Bridging the viral immuno-evolutionary gap.

The ability of viruses to adapt and evolve as they spread through a population remains a global concern. Immune responses drive viral evolution, but our understanding of how specific selective pressures from distinct mediators of innate and adaptive immune responses within individual hosts influence long-term pathogen evolutionary trajectories is limited. Here, we argue that there is a critical need for experiments that bridge individual host studies on the one hand and population-level epi-evolutionary studies on the other. Current frameworks that investigate how immune parameters individually affect viral abundance or clearance need to be more frequently coupled with sequencing data across viral genomes. Such integration would enable the identification of potentially distinct immune-mediated selection pressures on viruses, thereby better informing the design of future cross-scale experimental models. Resolving how immune factors influence the emergence of novel viral variants will be essential to better predict and effectively manage viral evolution.