Figure 1.

Characteristics of phage-host dynamics in the healthy infant and adult gut. During the first 2-3 years of life, there are drastic changes in the bacterial and phage communities in the healthy gut. Kill the Winner dynamics dominate during childhood, resulting in lytic replication and high phage abundance and diversity, particularly within the phage order Caudovirales (red). Piggyback the Winner dynamics are hypothesized to be prevalent in the healthy adult gut, where an increase in lysogenic replication coincides with a decrease in overall phage abundance and diversity. The abundance of Microviridae (blue) increases, and the phage community remains relatively stable over time. An absence of phage predation may lead to the expansion of bacterial abundance and diversity observed in the adult gut. Image created using BioRender.