Figure 7. (A) Structure of the hybrid protein used for immunisation. The hybrids were generated as described in Figure 6. For abbreviation see Figures 4 and 6. The origin of the fusion peptide (FP) and the membrane spanning domain (MSD), either from gp41 of HIV-1 or from p15E of PERV are indicated. Hybrid 3 and 4 lack the FPPR and MSD, in hybrid 4 the FPPR region was shifted. (B) Localization of the epitopes recognized by sera from animals immunised with the different hybrid proteins. The first part of the sequence corresponds to the FP/FPPR sequence, the second part to the MPER. The sequences of the epitopes of 2F5 and 4E10 are in bold, the sequences of the peptides shown to enhance the binding of 2F5 and 4E10 to their epitopes when interacting are underlined.