Figure 3

Pharmacodynamics of HIV-1. The effect of the antiretroviral treatment is to suppress viremia below the level of detection. This occurs in the first weeks after start of therapy. In particular, within two/three weeks there is an exponential decline of viremia of about two orders of magnitude. This rapid ablation of initial viremia reflects the decay of productively infected cells due to the action of reverse transcripatase inhibitors. The decline then gets slower and slower. This is mainly due to the action of the protease inhibitors on infected cells. Finally, the viral decline levels off, as a result of sub-optimal drug effectiveness, reservoirs of virus-producing cells that are unaffected by the drug, or the emergence of resistant virus strains. Solid line represents the average behavior of hundreds in silico patients, whereas colored dots correspond to selected in vivo patients.