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P Rivaille

Publications and source records attributed to P Rivaille.

At least 19 recordsLinked to original sources
PubMed1993

Immune response related to the molecular structure of a peptide from the cholera toxin B subunit.

Three forms of a peptide P50-75 from the cholera toxin B subunit in the absence of carrier or adjuvant were administered orally or intraperitoneally to C57Bl/6J mice. Mice were given P50-75 as the free monomer, as an octamer synthesized on the seven polylysine core proposed by Tam (S), or as an octamer synthesized on the epsilon-amino groups of a chain of eight Lys-Gly-Gly units (C). P50-75, presented to the immune system, as monomer or polymers, generated similar serum titres of anti-cholera toxin (CT) antibodies. However, mice immunized orally with the polymers S and C were better protected against the intestinal effects of the toxin than mice immunized with the free monomer P50-75. S and C are more effective than P50-75 or the B subunit in increasing the amounts of total IgA secreted into the intestine and, moreover, the anti-CT IgA neutralized toxin activity. The amounts of anti-CT subclasses (IgG1, IgG2a, IgG2b, and IgG3 plus IgM) produced by the antigens depended on how the peptide P50-75 was presented for priming to the mice boosted thereafter with the B subunit.

Administration, Oral↗
PubMed1991

A novel calcitonin carboxyl-terminal peptide produced in medullary thyroid carcinoma by alternative RNA processing of the calcitonin/calcitonin gene-related peptide gene.

The calcitonin/calcitonin gene-related peptide gene expresses two different mRNAs by tissue-specific alternative processing. The calcitonin mRNA is produced in thyroid C cells by splicing of the first three exons to the fourth polyadenylated exon. It encodes a protein precursor containing an amino-terminal peptide, calcitonin, and a carboxyl-terminal peptide (CCP I). Calcitonin gene-related peptide (CGRP) mRNA is produced in neuronal cells by splicing of the three common exons to the fifth exon and the polyadenylated sixth exon, leading to the production of a CGRP precursor. Our studies concerning the expression of the calcitonin/CGRP gene in human medullary thyroid carcinoma revealed the presence of a new RNA transcript. Amplification by polymerase chain reaction and direct sequencing showed that the novel transcript is composed of exons 1, 2, and 3, part of exon 4, exon 5, and a polyadenylated exon 6. This transcript contains an open reading frame coding for the known amino-terminal and calcitonin peptides, as well as for a novel calcitonin carboxyl-terminal peptide, CCP II. This third alternative pathway utilizes an internal donor site within the exon coding for calcitonin. The presence of CCP II was demonstrated in plasma and thyroidal tissues of medullary thyroid carcinoma patients, implying that this novel mRNA is actively translated in medullary thyroid carcinoma.

Amino Acid Sequence↗
PubMed1990

Repetitive BOP coupling (REBOP) in solid phase peptide synthesis. Luliberin synthesis as model.

The coupling reagent (benzotriazol-1-yloxy)tris-(dimethylamino)phosphonium (BOP) hexafluorophosphate was tested in the synthesis of luliberin (LH-RH) with inexpensive classically protected Boc-amino acids, in slight excess, and benzhydryl amino resin, without any other additive. The good solubility of this reagent and its by-products is of particular interest for automated peptide synthesis. [D-His2]LH-RH was also synthesized and compared with LH-RH by proton nuclear magnetic resonance spectroscopy. As shown by the biological tests and the high performance liquid chromatography study, unprotected pyroGlu and Boc-His can be used without any significant racemization but Boc-His(Boc) was found to be preferable since it gave no detectable racemization and no by-products. The difficult isolation of the minority D-derivative from the crude preparation of LH-RH was resolved by a recycling procedure in reversed phase HPLC.

Amino Acid Sequence↗
PubMed1989

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

Secretory 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.

Animals↗
PubMed1989

Oral immunization with a free peptide from cholera toxin: local protection and IgA production.

It is frequently of great benefit for good protection against pathogens to elicit a local immunization. For example the importance of antibacterial as well as antitoxin local secretory IgA, for protection against cholera, has been underlined in several studies. We have already reported that oral administration of the peptide corresponding to the 50-75 sequence of cholera toxin (CT) B subunit elicits serum antibodies neutralizing CT activity. In this study we demonstrate that IgA with specificity to CT are present in intestinal secretions of mice immunized orally with the P50-75 or P30-50 peptides of CT B subunit. In addition local protection is observed in the intestine of P50-75 orally immunized mice. These results point out the potential of synthetic peptides as immunogens at the mucosal level.

Administration, Oral↗
PubMed1987

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

Sequential 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.

Animals↗
PubMed1986

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

The 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.

Administration, Oral↗
PubMed1985

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

Several 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.

Amino Acid Sequence↗
PubMed1985

Solid phase synthesis of two cholera toxin B subunit antigens.

The 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.

Animals↗
PubMed1982

Characteristics of guinea-pig immune sera elicited by a synthetic diphtheria toxin oligopeptide.

Several oligopeptides of different lengths contained within the Cys 186-Cys 201 first disulfide loop of the diphtheria toxin molecule have been synthesized by a solid-phase method. 125I-labeled rabbit antibodies raised against diphtheria toxin reacted specifically with oligopeptides linked to m-nitrobenzhydrylamine resin when the amino acid chain length was equal to or greater than 10 residues. The synthetic tetradecapeptide (STDP) corresponding to the sequence Gly 188-Cys 201 was used to immunize guinea-pigs. The immune sera obtained reacted with the whole diphtheria toxin molecule as judged by an antigen-linked immunosorbent assay. Anti-STDP sera exhibited a clear, albeit limited, neutralizing effect against the lethal action of diphtheria toxin on cultivated Vero cells. The anti-STDP sera were also able to partially block the ADP-ribosylation of elongation factor 2 mediated by whole diphtheria toxin. In contrast, anti-STDP sera were almost inactive on the enzymic activities of either toxin fragment A or crm 45, a mutant protein which lacks the 15,000 mol. wt C-terminal sequence of the toxin molecule. On the basis of the results obtained, a possible localization of the Cys 188-Cys 201 loop region on the toxin molecule is proposed.

Animals↗
PubMed1981

Active antitoxic immunization by a diphtheria toxin synthetic oligopeptide.

Diphtheria toxin (DT) is a single polypeptide chain of molecular weight 62,000 with two disulphide bridges. Immunization against diphtheria rests on the stimulation of antibodies against detoxified toxin which also combine with the native toxin. Because the antibodies differ functionally from each other, however, only some of them are able to neutralize toxicity. We have therefore set out to synthesize part of the amino acid sequence of the toxin whose function as a stimulator of antibodies might be less ambiguous, and have chosen the loop of 14 amino acids subtended by the disulphide bridge nearer the NH2 terminus of the molecule (Fig. 1). There is reason to think that this loop may be involved in the toxicity and immunological specificity of the molecule. We report here our finding that the tetradecapeptide (residues 188-201), when linked covalently with two different carriers, will elicit in guinea pigs antibodies which not only bind specifically with the toxin but neutralize its dermonecrotic and lethal effects. To our knowledge these results constitute the first example of successful active immunization against a lethal bacterial toxin using a synthetic antigen.

Amino Acid Sequence↗
PubMed1981

[Preparation of antisera against some sequences of somatostatin synthetized on resin. Application to the immunological detection of somatostatin systems: preliminary results (author's transl)].

Specific SRIF(1-14) fragments were synthetized on resin using conventional procedures. Rabbits received subcutaneously peptidyl resins in complete Freund adjuvant emulsion. The presence of antibodies was assessed by immunocytochemical and radioimmunological assays. 1. Peptidyl resins lead to antibodies production; their specificity depends on sequence and molecular configuration of the peptide on the resin. Anti-resin antibodies were not detected. 2. In the brain, SRIF(1-4) (in rat) and SRIF(10-13) (in garden-dormouse) can be demonstrated in neurophysins--positive cells of both paraventricular and supraoptic nucleus, but never in hypothalamic or extrahypothalamic SRIF(1-14)--positive neurophysin negative cells. 3. Endocrine cells of pancreatic islets contain SRIF(6-9) (in man) or SRIF(10-13) (in rat, mouse, garden-dormouse); generally, these cells are not detected by SRIF(1-14) anti-serum. Moreover, SRIF(10-13) positive cells are also detected by specific glucagon antibodies. However, it cannot be concluded that SRIF(10-13) antibodies reveal the common Thr-Phe-Thr-Ser fragment in the entire glucagon molecule. It is postulated that antibodies to several SRIF tetrapeptides reveal molecular fragments provided by the functional cleavage of an hypothetical prohormone or by the inactivation of SRIF(1-14) molecule in target cells.

Animals↗
PubMed1976

Comparative in vitro biological activity of 1-34 N-terminal synthetic fragments of human parathyroid hormone on bovine and porcine kidney membranes.

1-34 N-terminal fragments of human parathyroid hormone with sequences according to Brewer et al (hPTHB) and to Niall et al (hPTHN) were synthesized and compared for their ability to activate bovine and porcine kidney cortex membrane adenylate cyclase. Results show that these two hormone sequences are able to activate these membranes but at least in this in vitro assay, hPTHN is about 10 times more active than hPTHB on bovine as well as on porcine membranes. These "apparent potencies" with respect to the potency of bPTH 1-34 in bovine and porcine membrane assay systems are respectively 4% and 11% for hPTHB and 39% and 156% for hPTHN. These relative potencies may be interpreted as corresponding to species specificity of the hormone receptor structural relationships.

Adenylyl Cyclases↗