 This study investigates the safety, tolerability and PKs of GSK2838232 with and without Ritonavir, and to evaluate different formulations of GSK2838232 in healthy subjects. This study will evaluate higher single and RTV boosted doses to support continued clinical development of GSK2838232 at clinically relevant doses, and subsequently in those infected with HIV in a dose ranging phase 2 study. The study is conducted in 2 parts: Part A and Part B, study Part A and Part B may be conducted in parallel. Approximately 20 healthy subjects will be enrolled into the study, 8 in Part A and 12 in Part B. Part A is a double-blind, randomized, placebo-controlled, 4-period, single dose escalation design. Subjects will be randomized 3:1 to receive GSK2838232 or placebo. Subjects randomized to placebo will receive placebo in all four periods. Following completion of Period 2 PK assessments at 96hr post-dose, subjects will begin daily dosing of RTV 100mg for a total of 26 days. 