Summary: Global stability is analyzed for a general mathematical model of HIV-1 pathogenesis proposed by

*P.W. Nelson* and

*A.S. Perelson* [Math. Biosci. 179, No. 1, 73–94 (2002;

Zbl 0992.92035)]. The general model includes two distributed intracellular delays and a combination therapy with a reverse transcriptase inhibitor and a protease inhibitor. It is shown that the model exhibits a threshold dynamics: if the basic reproduction number is less than or equal to one, then the HIV-1 infection is cleared from the T-cell population; whereas if the basic reproduction number is larger than one, then the HIV-1 infection persists and the viral concentration maintains at a constant level.