Results of linear antibody epitope mapping. For each group, the sera from mice in the same group were combined together in equal volume and mixed. The mixed serum was then assayed in duplicated wells. The averages of duplicated original OD values from vaccination groups were graphed into figures. The straight-scatter lines in the figures indicate the threshold value, which is 2-fold of the OD values from mock vector controls against each corresponding peptide(2-fold of sv1.0 is the cutoff value for groups immunized with DNA only; 2-fold of sv1.0+wild type TTV is the cutoff value for groups immunized DNA plus rTTV). Though vaccination stimulated no significant responses to the majority of peptides, several highly reactive epitopes were identified across the full amino acid sequences of HIV-1rl42 gp145, including p22~p27 of C1, P76/p77 of V3, p86/p87 of C3, p116~p119 of C5 and p145/146 between the 2 HR (heptad repeat) regions.