Fig 4. A representative AMP simulation using the initial model (serum PK and in vitro PD).

For each dosing arm in the trial (placebo, 10 mg/kg, and 30 mg/kg, respectively), we simulated 40 functional exposures (based on a 3% incidence rate per year) and plotted viral load data: colored solid lines are simulated viral loads and open circles represent viral load measurements given the sampling frequency of the AMP trials. Dashed black line indicates a limit of detection at 30 copies/mL. Each exposure is initialized with a single infected cell carrying a randomly drawn viral strain (IC50) and a VRC01 concentration which follows randomly drawn participant PK kinetics. To normalize correctly, we account for the fact that in the placebo model (A), some functionally exposed participants naturally clear the infection due to variability in host immune parameters and stochastic simulation. Many functional exposures are blocked by VRC01. The trial admits excellent prevention efficacy: PE = 1 − 6/36, or 83%, in B) the low dose arm and PE = 1 − 3/36, or 92%, in C) the high dose arm.