This is an open-label, randomized, single-dose, crossover trial in healthy volunteers. Crossover means that participants may receive different interventions sequentially during the trial. Randomized means that you will be assigned to a treatment sequence by chance, like flipping a coin. Open-label means that you and your physician will know what treatment you will receive. The study will consist of 3 phases: a screening phase, a treatment phase and a follow-up phase. Total study duration for an individual participant will be approximately 11 weeks. Once found eligible after the screening phase, participants will take part in one of the two parts of the treatment phase. In the first part, a group of 16 participants will receive two treatment sessions, A and B. The order in which the treatments are given will be determined by chance. In treatment A, 200 mg (2 tablets) ETR (etravirine) will be given twice a day from day 1 to 10 with a morning dose only on day 11. In treatment B, 750 mg (2 tablets) TVR (telaprevir) will be given from day 1 to 17 every 8 hours with a morning and afternoon dose only on day 18 and 200 mg ETR will be given twice a day from day 8 to 17 with a morning dose on day 18. In between the 2 sessions, there will be at least 14 days. In the second part, another group of 16 participants will receive 2 treatment sessions, C and D. The order in which these treatments are given will be determined by chance. In treatment C, 25 mg (1 tablet) TMC278 will be given once a day from day 1 to 11. In treatment D, 750 mg (2 tablets) TVR (telaprevir) will be given from day 1 to 18 every 8 hours and 25 mg TMC278 will be given once a day from day 8 to 18. In between the 2 sessions, there will be at least 14 days. All treatments will be taken food. In treatments A and C, participants will come to the unit the day before dosing and in the mornings of day 1, 9 and 10 and for a whole day on day 11. Only in treatment C, overnight stay from day 11 to day 12 is foreseen. In treatment B, participants will come to the unit the day before dosing and in the mornings of days 1, 5, 6, 8, 16 and 17 and for a whole day on days 7 and 18. In treatment D, participants will come to the unit the day before dosing and in the mornings of days 1, 5, 6, 8, 12, 16 and 17 and for a whole day on days 7 and 18 with overnight stay from day 18 to 19. Five to 7 days after last dosing, participants will have a last follow-up visit at the unit (follow-up phase). During the study, safety will be monitored, and during the treatment phase, at specified timepoints, blood samples will be taken for pharmacokinetic evalutions (effect of the body on the drugs). In treatment A, 2 tablets ETR will be given twice a day from day 1 to 10 with a morning dose on day 11. In treatment B, 2 tablets TVR will be given every 8 hours from day 1 to17 with only 2 doses on day 18 and 2 tablets ETR twice a day from day 8 to 17 with a morning dose only on day 18. In treatment C, 1 tablet TMC278 will be given oncy a day from day 1 to 11. In treatment D, 2 tablets of TVR will be given every 8 hours from day 1 to 18 and 1 tablet TMC278 once a day from day 8 to 18.