Baseline pharmacokinetic (PK) assessments will be performed before the start of the first infusion. Peak PK sampling for 3BNC117 will occur following the completion of the 3BNC117 infusion prior to the start of the 10-1074 infusion. Peak PK sampling for 10-1074 will occur following the completion of the 10-1074 infusion. Additional PK assessments will occur at multiple time points during study follow up. Study participants will be followed for a total of 24 weeks following the final antibody infusion.