CD4 and infection: In terms of HIV infection/AIDS‐relevant events, host changes in different tissues are captured.[4, 146, 147, 148, 149, 150, 151, 152, 153, 154, 155, 156, 157, 158, 159, 160, 161, 162, 163, 164, 165, 166, 167, 168, 169, 170, 171, 172, 173, 174, 175, 176, 177, 178, 179, 180, 181] For instance, during infection, the abundance of CD8+ effector memory T cells is increased,[147] while the amount of CD101‐expressing CD4+ T cells is reduced.[158] Indeed, T cell abundance changes are a typical feature of HIV infection.