Anti-HIV treatment history of Patient 1. Viral load (black square) and CD4+ T-cell counts (grey circle) are plotted against the days of anti-HIV treatment. A, B, ... O indicate sampling time points. DC (Drug Combinations) 1, 2, ... 5 represent five periods, respectively, in which different drug combinations were administered, with the drugs used indicated below. NNRTIs: non-nucleotide reverse transcriptase inhibitors; NRTIs: nucleotide reverse transcriptase inhibitors; PIs: protease inhibitors.