This study will enroll healthy adults who are not infected with HIV or TB. Participants will be enrolled into one of three arms, with Arms 1 and 2 each consisting of two groups. Participants in Arm 1 will be randomly assigned to receive PA-824 alone or EFV alone followed by EFV plus PA-824 in one of two sequences. Participants in Arm 2 will be randomly assigned to receive PA-824 alone or LPV/r alone followed by LPV/r plus PA-824 in one of two sequences. For participants in Arms 1 and 2, there will be a 14-day washout period between treatments, where participants will not receive any medication. Participants in Arm 3 will receive PA-824 alone, followed by RIF alone, and then RIF plus PA-824. Participants in Arms 1 and 2 will attend outpatient study visits at study entry and either Days 3, 22, and 29 or Days 7, 36, and 39, depending on which group they are in. Participants in Arm 3 will attend outpatient study visits at study entry and Days 3, 10, and 15. At most study visits, participants will undergo a physical examination, vital sign measurements, medication and medical history review, and blood collection. Participants will complete a medication and symptom diary throughout the study.