Identification of epitope specificity of macaque Fabs by competition ELISA with mouse monoclonal antibodies of defined specificity. Competition for binding of mouse monoclonal antibodies with a dilution series of Fab 102 (a) and Fab 202 (b) as the competitor. (c) Competition of Fabs 101, 102, 103, and 104 with V3 loop-specific monoclonal antibody KK45 as measured by the binding of the mouse monoclonal antibody. (d) Competition of Fabs 201, 202, 203, and 204 with antibody 201-IgG1 as measured by binding of the whole macaque antibody. OD, optical density.