A mechanistic theory to explain the efficacy of antiretroviral therapy.

In the early years of the AIDS epidemic, a diagnosis of HIV-1 infection was equivalent to a death sentence. The development of combination antiretroviral therapy (cART) in the 1990s to combat HIV-1 infection was one of the most impressive achievements of medical science. Today, patients who are treated early with cART can expect a near-normal lifespan. In this Opinion article, we propose a fundamental theory to explain the mechanistic basis of cART and why it works so well, including a model to assess and predict the efficacy of antiretroviral drugs alone or in combination.