Antibody-genes undergo molecular events that produce unique binding-sites that recognize specific epitopes, thus, leading to B-cell clonal variation. As a result, different binding-site structures (paratope internal images) are produced even when two distinct B-cells bind one and the same epitope. Paratope structural variation can be exploited to enable one to evaluate antibody-diversity in a single polyclonal serum sample. This is accomplished through the selection of antibody-specific peptides isolated from combinatorial phage displayed peptide libraries. As an example, we demonstrate the analysis of macaque sera containing passively administered antibodies, given as a therapeutic vaccine and antibodies actively produced by the virus-infected monkeys.