Figure 4

The anti-PfRH5 mAb 5A08 specifically recognizes the affinity-selected VLP. (A) ELISA performed with different mAbs against with the 5A08-VLP, and a MCA-5792-VLP, show that the 5A08-VLP reacts with the anti-PfRH5 5A08 mAb, but not with the two other anti-PfRH5 mAbs, 2E11 and 5A03, nor with MCA-5792 used here as a control, which reacts well with its own selectant. MCA-5792 recognizes Staphylococcus aureus peptidoglycan; St8 is a VLP affinity-selected for its ability to interact with MCA-5792. (B) The 5A08-selected VLP elicits antibodies that recognize the synthetic SAIKKPVTGGGC peptide. ELISA assay shows the anti-peptide antibody titers of sera from mice immunized with the synthetic VLP bearing the SAIKKPVTGGGC peptide. The synthetic peptide was bound to the plates by chemical cross-linking. Pooled pre-immune sera from the immunized mice show negligible anti-VLP peptide antibody titers in naïve animals. Pooled sera from mice immunized with MS2 itself also showed some reaction with the peptide, but it was much lower and decreased quickly with dilution. However, sera from all three mice immunized (indicated as 1, 2 and 3) showed high anti-VLP peptide antibody titers, two of the three giving signals well above background levels beyond the 1:5,120 dilution point.