Predicted that for the antibody to be effective in neutralizing HIV-1, the time it takes to disable an epitope must be shorter than the time the epitope remains in the long-lived conformation induced by antibody binding. For 4E10 and 2F5, whose dissociation rate constants for the breakup of the long-lived complex k{d 10{3 s21 (Table 1 and [4,17]), the time to disable an epitope must be about five