High titer response against a malarial antigen depends on the flanking sequence of the immunizing peptide conjugate

The immunogenicity of peptides conjugates containing the epitope STNS, recognized by inhibitory monoclonal antibodies directed against the Plasmodium falciparum merozoite surface antigen MSA2, was investigated. The sequence of the flanking regions was critical in determining the response against the central epitope. In the best immunogen tested, this flanking sequence was not related to the sequence of the surface antigen itself but nevertheless gave rise to a strong anti-MSA2 protein response as judged by Western blotting and immunofluorescence. This finding illustrates the importance of defining such flanking sequences in optimizing peptide based vaccines.