CD4 and infection: In a Kaplan-Meier survival analysis, in which we defined the endpoint as having a CD4+ T cell count >350 cells/mm3 (WHO recommendation for initiation of anti-retroviral therapy [71]), we observed a statistically significant difference in the number of individuals that maintain CD4+ counts >350 cells/mm3 between those infected with viruses that replicate very poorly (RC<1) and those infected with highly replicating viruses (RC>2), within the first 3 years of infection (Figure 7B, Mantel-Cox test p = 0.029).