What is the significance of posttreatment control of HIV infection vis-à-vis functional cure?

An important challenge of HIV research today is ‘functional cure’ or HIV remission, that is interventions to keep viral load at low or undetectable level after interrupting combined antiretroviral treatment (cART). It has been suggested that so-called ‘elite controllers’ may provide important clues in this quest [1]. By definition elite controllers are able to maintain their viral loads below the clinical level of detection (<50 copies of viral RNA/ml) ‘spontaneously’ that is without ever being treated [2,3]. During the last few years reports have emerged on patients who were first treated with cART and who kept control over the virus after treatment interruption. These patients have been called ‘secondary controllers’ [4] or ‘posttreatment controllers’ (PTC) [5]. This PTC status may provide additional information to develop a functional cure.