Epitopes of the 44-68 human parathyroid hormone fragments: the importance of specific hydrophilic peptide sequences.

International audienceSeveral pentapeptides included in the 44-68 sequence of human parathyroid hormone (hPTH) were synthesized simultaneously on benzhydrylamine and m-nitrobenzhydrylamine resins. The first polymer gave the free peptide and the second the peptidyl-resin complex. An ELISA test carried out with each peptidyl-resin complex showed that all the anti-44-68 hPTH antibodies raised in different animal species are directed against the same hPTH pentapeptidic sequence. This sequence is very hydrophilic and is specific to the hormone. This study demonstrates the importance of specific peptide chains in an epitope

Repetitive BOP coupling (REBOP) in solid phase peptide synthesis

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Synthesis of a new carrier for immunization: polytuftsin. Two examples of its use with peptides selected in the hepatitis B surface antigen.

International audienceSequential poly(Arg-Thr-Lys-Pro) consisting mainly of the repeat of tuftsin Thr-Lys-Pro-Arg was synthesized by condensing the p-nitrophenyl ester of Arg(HCl)-Thr-Lys-(2-Cl-Z)-Pro in the presence of HOBt. Two haptenic sequences of the Pre-S region of hepatitis B virus antigen (10-26 and 39-55) were prepared by solid phase and coupled to polytuftsin via glutaraldehyde. The peptides, either free or coupled to polytuftsin, were administrated to mice and the antisera were assayed by ELISA. Coupling the peptides to the polypeptide significantly improved the anti-peptide antibody titer in Freund complete adjuvant or in NaCl 0.9%. Cross-reaction between antibodies induced by the peptides and the native protein was also improved. Polytuftsin alone is very poorly immunogenic

Neutralization of cholera toxin by rat IgA secretory antibodies induced by a free synthetic peptide.

International audienceSecretory immunoglobulin A (sIgA) is the major immunoglobulin in the bile of several species. They contribute to local immune defences of the gut. The protection against cholera toxin (CT) is due to the presence of specific sIgA in the bile and in the gut. We have already reported that oral administration of the peptide corresponding to the sequence 50-75 of cholera toxin B subunit elicits serum antibodies neutralizing CT activity, and that IgA and local protection are observed in the intestine of P50-75 orally immunized mice. In this study, we demonstrate the potential of this synthetic peptide as immunogen without carrier or adjuvant, not only in a strain known to be sensitive to CT, but also in an outbred one. Furthermore, this peptide stimulates the mucosal immunity, since we show that P50-75 induced-sIgA purified from rats bile and serum, are capable of neutralizing CT activity in the in vivo intestinal ligated loop test

Solid phase synthesis of two cholera toxin B subunit antigens.

International audienceThe 30-50 and 50-75 sequences of the cholera toxin beta chain including the amino-acids that are thought to be involved in toxin-receptor binding have been synthesized using the solid phase method. They were then purified by gel permeation and ion exchange chromatography. Both these free peptides induced serum antibodies recognising the native toxin after oral or intraperitoneal administration. Only the antibodies raised against the 50-75 peptide, however, were able to neutralize toxin activity

Oral immunization with a synthetic peptide of cholera toxin B subunit. Obtention of neutralizing antibodies.

International audienceThe ability of free synthetic fragments of the cholera toxin (CT), administered by parenteral or oral route, without adjuvant, to induce antibodies cross-reacting with CT was tested. Two peptides corresponding to the sequences 30-50 and 50-75 of the CT beta chain were selected and synthesized. Both free peptides, given intraperitoneally or orally, without adjuvant, elicited seric antibodies cross-reacting with CT. The anti-(P50-75) antibodies were able to neutralize the CT activity. Our results show that protection against a toxin at the systemic level can be obtained with a synthetic peptide even when administered by an oral route