• Confirmed HIV-1, documented by any licensed rapid HIV test or HIV enzyme or chemiluminescence immunoassay (E/CIA) test kit at any time prior to study Step 1 entry AND Confirmed by one of the following:

‣ A second antibody test from different manufacturers or based on different principles and epitopes (combination antigen-antibody-based rapid tests may be used)

⁃ HIV-1 antigen

⁃ Plasma HIV-1 RNA viral load or

⁃ A licensed Western blot

∙ NOTE: The term licensed refers to a US FDA or DAIDS Clinical Laboratory Oversight (DCLOT) approved test.

∙ WHO (World Health Organization) and CDC (Centers for Disease Control and Prevention) guidelines mandate that confirmation of the initial test result must use a test that is different from the one used for the initial assessment. A reactive initial rapid test should be confirmed by either another type of rapid assay or an E/CIA that is based on a different antigen preparation and/or different test principle (e.g., indirect versus competitive), or a Western blot or a plasma HIV-1 RNA viral load.

• ART-naïve \[NOTE: Prior use of PrEP or PEP is allowed, except use of long-acting ARVs (e.g., cabotegravir, rilpivirine) within the last 24 months.\]

• CD4+ T cell count \>200 cells/mm3 obtained within 28 days prior to study entry at any Network-approved non-US laboratory that is (IQA) certified.

• Plasma HIV-1 RNA \>1000 copies/mL obtained within 28 days prior to study entry performed at any Network-approved non-US laboratory that operates in accordance with Good Clinical Laboratory Practices (GCLP) and participates in appropriate external quality assurance (EQA) programs.

• For study candidates of child-bearing potential, negative urine or serum pregnancy test within 72 hours prior to study entry by any Network-approved non-US laboratory or clinic that operates in accordance with GCLP and participates in appropriate EQA programs.

∙ \[NOTE A: Persons who are of child-bearing potential are individuals who have not been post-menopausal for at least 24 consecutive months, who have had menses within the preceding 24 months, and who have not undergone surgical sterilization, specifically hysterectomy and/or bilateral oophorectomy, tubal ligation, or bilateral salpingectomy.\] \[NOTE B: Acceptable documentation of hysterectomy and bilateral oophorectomy, tubal ligation, and tubal micro-inserts are written documentation or oral communication from a clinician or clinician's staff documented in source documents (physician report/letter, operative report or other source documentation in the patient record, discharge summary, laboratory report, etc.). Participant-reported history is acceptable for documentation of menopause.\]

• Persons of child-bearing potential who are able to become pregnant must agree to use two methods of contraception, if participating in sexual activity that could lead to pregnancy. One contraceptive method must be from the list of highly effective methods listed below. The second method of contraception must be a barrier method or abstinence. Both methods of contraception must be used during Step 1. The two effective forms of birth control have to be used for 10 days before receiving the first study drug infusion, for at least 12 months after the product infusion, and until ART is reinitiated and viral suppression is achieved.

∙ Acceptable methods of contraception include:

• Contraceptive subdermal implant

• Intrauterine device or intrauterine system

• Combined estrogen and progestogen oral contraceptive

• Injectable progestogen

• Contraceptive vaginal ring

• Percutaneous contraceptive patches

• Partner sterilization with documentation of azoospermia prior to the participant's entry into the study, and this individual is the sole partner for that participant.

∙ \[NOTE: Documentation of partner sterility can come from the site personnel's review of participant's medical records, medical examination and/or semen analysis, or medical history interview provided by the participant or the partner. Self-reported documentation of reproductive potential should be entered in the source documents.\]

• Individuals engaging in sexual activity that could lead to their partner becoming pregnant must agree to use a barrier method of contraception to avoid pregnancy in a spouse or partner of reproductive potential. The barrier method must be used to prevent partner pregnancy during Step 1 and for at least 12 months after the product infusion.

• Ability and willingness to use a barrier protection or abstinence from sexual intercourse during Step 1 until viral suppression is achieved, during the ATI period (Steps 2-3), and until plasma HIV-1 RNA is less than limit of detection after ART restart (Step 4) with partners without HIV or whose HIV serostatus is unknown in order to prevent HIV transmission to sexual partners.

• Ability and willingness to initiate ART at enrollment.

• Ability and willingness to participate in scheduled study visits, including ATI per the SOE.

• Ability and willingness to provide informed consent.

• Documented negative hepatitis B virus (HBV) surface antigen (HBsAg) obtained within 16 weeks prior to Step 2 registration by any Network-approved non-US laboratory that operates in accordance with GCLP and participates in appropriate EQA programs.

• Documented negative HCV antibody (anti-HCV), negative HCV RNA PCR, or negative HCV antigen obtained within 16 weeks prior to Step 2 registration by any Network-approved non-US laboratory that operates in accordance with Good Clinical Laboratory Practices (GCLP) and participates in appropriate EQA programs.

• Participants diagnosed with a bacterial sexually transmitted infection (STI) must have initiated treatment prior to Step 2 entry.

• Receipt of both bNAb infusions or placebo infusions during Step 1.

• HIV-1 RNA \<200 copies/mL obtained within 6 weeks prior to Step 2 registration at any Network-approved non-US laboratory that is VQA certified.

• CD4+ T cell count ≥450 cells/mm3 obtained within 6 weeks prior to Step 2 registration at any Network-approved non-US laboratory that is IQA certified.

• For participants of child-bearing potential, negative serum or urine pregnancy test within 48 hours prior to Step 2 entry at any Network-approved non-US laboratory or clinic that operates in accordance with GCLP and participates in appropriate EQA programs.

• Ability and willingness to use a barrier method of contraception or abstinence from sexual intercourse during Steps 2 and 3, and until plasma HIV-1 RNA is less than limit of detection, with all partners who are without HIV or whose serostatus is unknown in order to prevent HIV transmission to sexual partners.

• Ability and willingness to stop ART.

• Has not met ART restart criteria.

• Completion of protocol Step 2.

• Willing to continue ATI.

• Met ART restart criteria (section 3.0) during Step 2 or Step 3 OR Completed Step 3 and is not enrolling to ACTG A5385.