For example, in one infected individual (CH505), a CD4‐binding site‐directed bnAb developed24 that was aided in its evolution by a cooperating antibody lineage also directed at the CD4 binding site but that did not initially have neutralization breadth.23 During ongoing infection, this cooperating antibody lineage further evolved, developing bnAb activity.22 The latter example suggests that the development of neutralization breadth is a dynamic process and that conditions favorable to the evolution of bnAbs may persist during chronic infection in some individuals. This evidence concerns the gene CD4 and infection.