Viral load and CD4+ T cell count in SHIV
–infected macaques with (A) and without (B) coreceptor switch. (A) Macaque DE86 was infected by the intravenous route and DG08 was inoculated intrarectally. Dashed line designates the time of dual-tropic and X4 virus emergence in these animals. (B) Macaques BT78, CC39 were infected intravenously while DN57 was challenged intrarectally. Time to euthanasia for the five RPs is: w12 (DE86), w20 (DG08), w13 (BT78), w12 (CC39) and w30 (DN57).