Figure 5

Hypothetical model of the evolutionary dynamics of CXCR4 usage in relation to the age of each HIV-1 subtype epidemic. Recent data suggest that the proportion of patients with detectable emergence of CXCR4-using HIV-1 variants varies in relation to the age of the different subtype epidemics, with subtype D (high CXCR4 switch rate) being the oldest and subtype C (low CXCR4 switch rate) the youngest.