NFKB1 and infection: Our patient-derived Vpus, however, were able to reduce NF-κB activation even at lower levels of expression, with a complete ablation of signalling occurring at higher Vpu concentrations, suggesting that this may indeed be an important role of Vpu in vivo. Furthermore, the observation of a significant decline in signal-suppressive function over time in several individuals, in contrast to the other two functions examined, as well as the high activity observed in founder virus-derived Vpus, may be indiciative of this activity being most important in early stages of infection.