Quality of T-cell responses versus reduction in viral load: results from an exploratory phase II clinical study of Vacc-4x, a therapeutic HIV vaccine by Ellefsen-Lavoie K, Rockstroh J, Pollard R, Pantaleo G, Podzamczer D, Asmuth D, van Lunzen J, Arastéh K, Schürmann D, Peters B, Clotet B, Hardy D, Lazzarin A, Gatell J, Sommerfelt MA, Baksaas I, Wendel-Hansen V, Sørensen B