Small peptides induce antibodies with a sequence and structural requirement for binding antigen comparable to antibodies raised against the native protein.

Abstract

Antisera were raised against the chemically synthesized peptide corresponding to each epitope of three foot-and-mouth disease virus strains. Peptide synthesis was further used to determine which amino acid residues in each epitope are important for the specificity of antisera raised against the whole virus. The specificity of the antibody paratope for its epitope was shown to depend on structure as well as sequence. Anti-virus sera demonstrated a greater specificity for the homologous peptide than did the anti-peptide sera. Two of the three peptides were able to induce neutralizing antibodies against the homologous virus. The specificities of the antibodies present in the anti-peptide sera were also inferred from the reactions of each with related sets of peptides. The cross-reactions observed for the anti-peptide sera were readily explained in terms of the antibody specificities determined to be present. The findings also suggest that the diversity of antibodies raised against small peptides is limited and is determined by the immune system. A similar limited response to the native protein was observed, which may account for the high frequency with which anti-peptide sera react with the native homologous protein.Antibodies to protein epitopes are usually highly specific and able to distinguish between proteins differing by only a single amino acid in the region of antibody binding (1-3). Structural changes induced by denaturation or chemical modification of a protein may result in the complete loss of binding by antisera against the native conformation (4, 5). These observations have led to the conclusion that antibody specificity is determined by both the sequence of amino acids and the conformation at the region of binding. In contrast to the relatively stable structure of a protein in solution, small peptides are thought to exist in a multiplicity of transient conformational states in dynamic equilibrium (6, 7). Antibodies raised against short peptides often react well with the native protein at the region of sequence homology, when this region is located at the surface of the molecule (8-10). It may also be necessary to restrict the conformational freedom of immunizing peptides in order to obtain antibodies of the same specificity as those induced by the proteins themselves.To compare the specificity of the anti-protein response with the anti-peptide response, peptides were synthesized corresponding to an equivalent epitope of three foot-andmouth disease virus (FMDV) strains, each belonging to a different serotype of the virus. It was assumed that anti-virus sera raised against different viral serotypes would not crossreact at a neutralization epitope. The diversity of antibodies directed to a single epitope was compared for each pair of antisera (anti-peptide and anti-virus). The specificity of each of the anti-peptide sera was inferred from the relative reactivity for the homologous compared to the heterologous peptide.A replacement set was synthesized consisting of all of the peptides derived by ...

Neutralizing activity of anti-peptide antibodies against the principal neutralization domain of human immunodeficiency virus type 1

“…Peptides were synthesized on polyethylene rods and tested with MAbs in an ELISA according to established procedures (Geysen et al, 1984(Geysen et al, , 1985. A set of overlapping peptides of between two and 18 residues with sequences derived from the region between amino acids 296 and 331, and a set of nonapeptides IQRGPGRAF and RGPGRAFVT, in which each amino acid was substituted by the other 19 naturally occurring amino acids, were synthesized.…”

Specificity and Function of the Individual Amino Acids of an Important Determinant of Human Immunodeficiency Virus Type 1 that Induces Neutralizing Activity

“…Peptides were synthesized on solid supports and tested as described previously (Geysen et al, 1984(Geysen et al, , 1985. To prepare a set of replacement peptides (RNET) for RGPGRAFVT, IQRGPGRAF or ITKGPGRVI [these peptides start at positions 312 and 310 of gpl20 of strain HTLV-IIIB (molecular clone BH10) and at position 320 of gp120 of strain HTLV-IIIRF], each of the nine amino acids in the appropriate peptide was replaced, one at a time, by the other 19 natural amino acids, while the rest of the sequence remained the same.…”

“…This determinant resides on the C-terminal portion of the external envelope glycoprotein (gpl20) (Putney et al, 1986;Rusche et al, 1987Rusche et al, , 1988Goudsmit et al, 1988a, d). Using sera from HIV-l-infected humans 0000-8570© 1989 SGM and chimpanzees we identified reactive nonapeptides between amino acids 307 and 320 of strain HTLV-IIIB (molecular clone BH10) and between amino acids 320 and 330 of strain HTLV-IIIRF with the PEPSCAN method (Geysen et aL, 1984(Geysen et aL, , 1985. Polyclonal and monoclonal antibodies raised against whole or parts of gp 120 or raised against gp 160 reacted also with these nonapeptides.…”

A phage-displayed peptide can inhibit infection by white spot syndrome virus of shrimp

“…Short peptides from combinatorial libraries can act as 'surrogate' ligands of proteins that interact with other proteins if they possess the required critical residues. This is because the number of residues critical for binding may be rather small, even though the two interacting proteins can be fairly large (Geysen et al, 1985;Ruoslahti & Pierschbacher, 1986;Wells, 1996). The coat proteins of a virus may interact with other structural proteins resulting in changes to virus morphology that may affect cell surface receptors.…”