This clinical trial is focused on studying the effects of two new medications, GSK4004280 and GSK4011499, in adults who are newly diagnosed with HIV-1 infection and have not yet received treatment. The purpose of the study is to evaluate how these medications, taken as tablets, can help reduce the amount of the virus in the body over a period of 10 days. Participants will be randomly assigned to receive either one of the medications or a placebo, which looks like the medication but does not contain the active substance.

During the study, participants will take the medication or placebo orally, meaning by mouth, for up to 10 days. The study will monitor the safety and tolerability of the medications, which means checking for any side effects and how well participants can handle the treatment. The study will also look at how the body processes the medications, known as pharmacokinetics, to understand how the drugs are absorbed, distributed, and eliminated from the body.

Participants will have regular check-ups to measure the change in the level of HIV-1 in their blood from the start of the study to the end. The study will also track any adverse events, which are any unwanted effects that occur during the trial. After the 10-day treatment period, participants will begin a standard combination antiretroviral therapy, which is a common treatment for HIV-1 infection, to continue managing their condition.