Study to Evaluate the Safety and How the Body Handles a Single Dose of Subcutaneous (SC) and Intravenous (IV) Budigalimab in Adult Participants Living With Human Immunodeficiency Virus (HIV)

* Condition of generally good health, body mass index ≥ 18.0 to \< 35.0 kg/m2. * Laboratory values must meet acceptable criteria. * Human Immunodeficiency Virus (HIV-1) infected on antiretroviral therapy (ART) for at least 12 months prior to screening and on current ART regimen for at least 8 weeks prior to screening. * CD4 cell count ≥ 450 cells/μL at Screening and during the 12 months prior to Screening. * Plasma HIV-1 RNA below the lower limit of quantification at Screening and at least 6 months prior to Screening. * Participants agreeing to use an effective barrier method of protection (male and/or female condom) during sexual activity from Study Day 1 through last study visit for the purposes of prevention of HIV transmission.

* Participants with signs/symptoms associated with SARS-CoV-2 infection OR Current SARS-CoV-2 infection by any viral nucleic acid test completed within 7 days prior to the Day 1 dose. * Participants having history or ongoing diagnosis of acquired immunodeficiency syndrome (AIDS)-defining illness. * Participants having history of or active immunodeficiency (other than HIV). * Participants having active autoimmune disease or history of autoimmune disease that has required systemic treatment. * Prior therapy/exposure to budigalimab or any other immune checkpoint inhibitor \[e.g., anti-programmed cell death protein 1(PD-1), anti-PD-L1, anti-PD-L2, anti-CTLA4\]. * Participants having clinically significant medical disorders that might expose the subjects to undue risk of harm, confound study outcomes, or prevent the subject from completing the study. * Participants having active or suspected malignancy or history of malignancy (other than basal cell skin cancer or cervical carcinoma in situ) in the past 5 years. * Participants with history of or active tuberculosis (TB) at screening. * Participants having known psychiatric or substance abuse disorders that would interfere with adherence to study requirements. * Participants who have received immunomodulatory or immunosuppressive (including IV/orally administered \[PO\] steroids at any dose, but excluding steroids that are inhaled, topical or via local injection) therapy within 24 weeks prior to the first dose of study drug.