Figure 1.

The effect of combination antiretroviral therapy on HIV-1 coreceptor usage over time in representative study subjects. Patients 1, 2, 6, 8, and 10 received new combination therapy and patient 13 remained untreated. Arrows note the first time during the study period that a new combination of antiretroviral drugs was initiated. Two arrows appear if a patient received a two-drug regimen first, then HAART. The duration of treatment with each agent is indicated. PT., patient; AZT, zidovudine; 3TC, lamivudine; Rit, ritonavir; Ind, indinavir; Saq, saquinavir; d4T, stavudine; Nel, nelfinavir; ddI, didanosine; ddC, zalcitabine; Nev, nevirapine.