Fig 6. Simplified model showing the interplay between Env dynamics and drug neutralization.

All Env displays some degree of transience due to low barriers of energy between prefusion conformations; however, propensity for structural rearrangement determines neutralization by molecules that recognize the open state. Highly dynamic gp120 allows transient access to open state epitopes, while less dynamic strains are less sensitive to neutralization by open state recognizing molecules.