Biomedical subjects

M Bossus

Publications and source records attributed to M Bossus.

25 records · Page 2Linked to original sources

PubMed1992

Analysis of antigenicity and immunogenicity of five different chemically defined constructs of a peptide.

The aim of this study was to compare the antigenicity and the immunogenicity of five constructs of a peptide, including the peptide in single copy, a tandem repeat containing three copies, a copolymer with glutaraldehyde and two constructs based on the MAP (Multiple Antigenic Peptide) model, one containing two copies (MAP-2) and the other, eight copies of the peptide (MAP-8). The peptide used in this test was the 115-131 sequence derived from the rSm28-GST antigen of Schistosoma mansoni. All constructs were recognized by rSm28-GST specific antibodies in solid phase immunoassays. However, the binding was higher when the MAP-8 was used as antigen at least partly because of its better coating on the microtiter plates. In vitro lymphoproliferative assays showed that polymer was mitogenic, repeat and MAP-2 did not stimulate rSm28-GST specific T cells while MAP-8 induced a slight response. The injection of MAP-8 to rats led to important antibody and T cell responses higher than those obtained with the other constructs. The IgG2a (cytotoxic antibody in schistosomiasis)/IgG2c (blocking antibody) ratio was independent of the immunogen. Taken together these results demonstrate that both the antigenicity and the immunogenicity of a peptide containing T and B cell epitope(s) are strongly related to the molecular form whereby it is presented and that the MAP-8 construct can be useful in serodiagnosis or in vaccination trials using synthetic peptides.

Amino Acid Sequence↗

PubMed1992

Diagnostic value of a synthetic peptide derived from Echinococcus granulosus recombinant protein.

A specific monoclonal antibody (MAb; EG 02 154/12) directed against a protein epitope of Echinococcus granulosus antigen 5 was used to screen a cDNA library constructed from E. granulosus protoscoleces RNA. One clone designated Eg14 was selected and shown to code for an amino acid sequence partially homologous to that of the clone Eg6 previously identified with the same MAb. Hydrophobic cluster analysis showed that both recombinant antigens may adopt a similar alpha-helical organization and share a common conformational epitope. A synthetic peptide (89-122) mimicking the conformational site of Eg6 and Eg14 was constructed and demonstrated to be able to inhibit binding of the MAb and human hydatid sera to the Eg6 fusion protein (FP6) or to native hydatid antigens. To assess the diagnostic value of the peptide 89-122, we tested sera from patients infected with different parasites for their antibody reactivity with this peptide in ELISA. A high binding sensitivity and specificity of IgG-A-M antibodies were obtained with E. granulosus-infected patient sera. Moreover, the peptide 89-122 was found to be specifically recognized by IgE antibodies from patients with hydatid disease. These results indicate the particular interest of this synthetic peptide as a standardized antigen in diagnosis and treatment surveillance of hydatidosis.

Amino Acid Sequence↗

PubMed1992

Immunogenicity and antigenicity of the N-term repeat amino acid sequence of the Plasmodium falciparum P126 antigen.

The P126 protein, a parasitophorus vacuole antigen of Plasmodium falciparum has been shown to induce protective immunity in Saimiri and Aotus monkeys. In the present work we investigated its immunogenicity. Our results suggest that the N-term of P126 is poorly immunogenic and the antibody response against the P126 could be under a MHC restricted control in C57BL/6(H-2b) mice, which could be problematic in terms of a use of the P126 in a vaccine program. However, we observed that a synthetic peptide, copying the 6 octapeptide repeat corresponding to the N-term of the P126, induces an antibody response to the native molecule in C57BL/6 non-responder mice. Moreover, the vaccine-P126 recombinant induced antibodies against the N-term of the molecule in rabbits while the unprocessed P126 did not.

Amino Acid Sequence↗

PubMed1991

Antigenicity and immunogenicity of a multiple peptidic construction of the Schistosoma mansoni Sm-28 GST antigen in rat, mouse, and monkey. 1. Partial protection of Fischer rat after active immunization.

Among the schistosome proteins characterized as vaccine candidates, an Ag of 28 kDa (Sm-28-GST) has received considerable attention. It was shown to be antigenic in humans and protective in mice, rats, hamsters, and baboons. Synthetic peptides derived from its sequence have been used to characterize the immune response to the molecule and one of these, comprising aminoacids 115-131 has been shown to incorporate both T and B cell recognition sites in a variety of experimental models. An octameric ("octopus") construction of the 115-131 peptide has been synthesized and its antigenicity and immunogenicity have been examined. The octopus construct is immunogenic in rats, mice and baboons in the presence of CFA (for rodents) and Bacille-Calmette-Guérin vaccine (for primates) as adjuvants. This clearly indicates that the construction allowed the conservation of the immune sites of the cognate protein. Moreover, anti-octopus sera from immunized Fischer rats were able to mediate platelet-, macrophage-, and eosinophil-dependent cytotoxicity toward schistosomula. Rats immunized with the 115-131 octopus were partially protected against a challenge infection with Schistosoma mansoni cercariae and this was paralleled by an increased level of IgG and more importantly, of IgE Sm-28-GST-specific antibodies.

Amino Acid Sequence↗

PubMedDate not supplied

Improved detection of human antibodies to a Plasmodium antigen using a peptide modified with Aib residues.

A 17-mer sequence was selected as a model to study the influence of modifications of terminal ends both on the conformational of a peptide and on its antigenicity towards naturally developing antibodies. This sequence corresponded to a tandemly repeated motif, found in a long repetitive region, with high helical propensity, of a Plasmodium falciparum liver-stage antigen (LSA-1), immunogenic in man. Our model peptide was synthesized with ionizable or non-ionizable ends, or modified in both extremities by introduction of the helix-promoting residue alpha-aminoisobutyric acid (Aib). Helical contribution, absent in the 17 amino-acid sequence possessing ionizable ends, was detectable when non-ionizable ends were introduced, and dramatically increased in the Aib-modified analogue. The presence of ionizable ends totally abolished reactivity towards human sera, otherwise detectable with the peptide possessing non-ionizable ends. While modification by Aib residues was neither detrimental nor beneficial to antigenicity in solution, it clearly resulted in an improved sensitivity of the specific antibody detection when used as solid-phase antigen in ELISA.

Amino Acid Sequence↗

PubMedDate not supplied

Synthetic vaccines and HIV-1 hypervariability: a "mixotope" approach.

The hypervariability of the gp120 envelope protein principal neutralizing domain, the V3 loop, represents a major problem in the design of vaccines against HIV-1. We have designed a mixed V3 loop peptide, termed "mixotope," obtained in a unique synthesis, and containing around 7.5 x 10(5) different sequences of 22 to 25 residues, organized around the conserved GPGR tetrapeptide. Free or coupled to a carrier protein, the "mixotope" induced in rabbits broadly specific antibodies, which recognized different individual V3 loop sequences, and the native gp120 protein. The "mixotope" approach may allow researchers to focus vaccine strategy against hypervariable functional epitopes of various pathogens.

AIDS Vaccines↗

PubMedDate not supplied

Induction of antibodies against the Plasmodium falciparum p126 antigen in non-responder H-2b and partial-responder H-2d mice using synthetic peptides.

The p126 Plasmodium falciparum antigen is processed into two fragments, p50 and p73, the latter one containing the subfragments p47 and p18 when the schizonts rupture. An absence of antibody response against the p126 antigen has been reported recently in H-2b mice and limited to the p73 processed fragment in H-2d mice. Synthetic peptides corresponding to various domains of the molecule have been used to immunize mice in order to overcome the absence of an immune response. Synthetic peptides corresponding to the N-terminus of p50 or p18 as well as to the C-terminus of p47 were unable to induce anti-peptide antibodies when injected carrier-free or coupled to ovalbumin. Synthetic peptides corresponding to the C-terminus of p18 or composed of 6 or 9 serines were able to induce anti-peptide antibodies when injected coupled to a carrier protein. However, none of these antibodies was able to recognize the native p126 molecule. Various synthetic peptides corresponding to the 6-octapeptide [Nt47 (6 x 8)] or the 4-octapeptide [Nt47(4 x 8)] repeat sequence localized at the N-terminus of the p47 have also been used to immunize mice. No antibodies were generated using a carrier-free [Nt47(6 x 8)-Cys]2 or [Nt47 (4 x 8)-Cys]2 peptide, an octameric multiple antigen peptide construct [Nt47(6 x 8)]-MAP or the [Nt47(6 x 8)] coupled to one or two palmitic acids. In contrast, [Nt47(6 x 8)]-Cys coupled to either tetanus toxoid (TT) or ovalbumin (OVA) and [Nt47(4 x 8)]-Cys coupled to OVA induced antibodies against the synthetic peptide and the native p126 molecule in both H-2d and H-2b mice. A multiple antigen peptide construct [Nt47(4 x 8)-MSP-3b]-MAP containing 4 [Nt47(4 x 8)] and 4 [MSP-3b] also induced antibodies against the synthetic peptide [Nt47(4 x 8)-Cys]2 and the native p126 molecule in both H-2d and H-2b mice.

Amino Acid Sequence↗