Proof of Concept Treatment Study of Orally Administered VH4004280 or VH4011499 in HIV-1 Infected Adults (CINNAMON)

Inclusion Criteria: Participants who are overtly healthy (other than HIV-1 infection). Screening cluster of differentiation-4 (CD4+) T-cell count greater than or equal to (≥)200 cells/microliter (µL). Documented HIV-1 infection and Screening plasma HIV-1 RNA ≥3000 copies/milliliter (mL). Treatment-naïve: Defined as no antiretroviral therapy received after the diagnosis of HIV-1 infection. Prior use of oral pre-exposure prophylaxis (PreP) is permitted. Prior use of parenteral PreP is exclusionary. Has body mass index (BMI) within the range of 18.5-31.0 kilograms per meter square (kg/m^2). Participants male at birth must use male condoms and participants female at birth who are of childbearing potential must be using acceptable forms of birth control. Participants capable of giving signed informed consent. Participant must be willing and able to start locally accessible and commercially available combination antiretroviral therapy after the monotherapy period. Exclusion Criteria: Women who are breastfeeding or plan to become pregnant or breast feed during the study. Participants with acute HIV infection. Any evidence of an active Centers for Disease Control and Prevention (CDC) Stage 3 disease. Untreated syphilis infection. Ongoing malignancy other than certain localised malignancies. Treatment with immunomodulating agents or any agent with known anti-HIV activity. Has exclusionary psychiatric, hepatic, cardiovascular gastrointestinal, renal condition. Participant having any condition which, in the opinion of the investigator, may interfere with the absorption, distribution, metabolism or excretion of the study drugs or render the participant unable to take oral medication. Participants having exclusionary electrocardiogram (ECG) findings. Participants who have been exposed to any prohibited medication or vaccine. Participant positive for hepatitis B or hepatitis C. Participants with exclusionary safety laboratory (e.g Grade 3 or greater abnormality). Participants who have positive results for illicit drug use, regular use of drugs of abuse and/or excessive alcohol use.