Arm A: Patients receive treatment as in Arm D of Step 1. Arm B: Patients receive treatment as in Arm C of Step 1. Arm C: Patients receive treatment as in Arm B of Step 1. Arm D: Patients receive treatment as in Arm A of Step 1. Arms A, B, C, and D: Patients who fail Step 2 treatment proceed to Step 3. Arms E and F: Patients with virologic failure on Step 1 proceed immediately to Step 3.