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We have previously shown that a mAb that inhibits the enzymatic activity of the Schistosoma mansoni 28-kDa glutathione S-transferase (Sm28 GST) also reduces female worm fecundity and egg viability in vivo and in vitro. By peptidic epitope mapping and an activity reconstitution assay, the carboxyl terminus (CT) amino acid residues 190-211 and to a lesser extent the truncated amino terminus (NT) residues 10-43 of the enzyme were identified as mAb recognition sites. Sera from rats immunized with the NT (10-43) and CT (190-211) peptides showed a partial inhibitory effect on Sm28 GST activity in a late phase (6 to 7 wk) but not in an early phase (2 to 4 wk) after immunization. Passive transfer of Sm28 GST-inhibiting anti-N- and C-terminal sera, but not of the noninhibitory sera, protected the infected mice by reducing tissue egg deposition and the ability of eggs to hatch. In active immunization experiments, the CT peptide significantly decreased the worm burden (37 to 40%) in mice as did the rSm28 GST (28 to 52%). In terms of tissue egg deposition and egg-hatching ability, immunization with both the NT and CT peptides reproduced the reduction observed after immunization with rSm28 GST. A constant reduction in egg numbers was noted in the small intestines and the livers of the immunized mice. A clear reduction in the ability of intestinal or hepatic eggs to hatch was observed. The results are discussed in terms of the conformational participation of the NT and CT of Sm28 in the expression of GST activity.

In vivo priming of CTL requires the association with MHC class I molecules of peptides derived from the processing of endogenously produced proteins. Immunization with exogenous proteins or peptides rarely induces MHC class I-restricted CTL unless they are associated with lipidic compounds. The capacity to induce CTL was compared in synthetic peptides and simple lipopeptides containing the Immunodominant MHC class I H-2Dd-restricted T-cell epitope of HIV-1 gp160. In contrast with free peptides in saline, lipopeptides induced strong primary CTL responses in vivo. These CTL were able to lyse cells infected with a recombinant vaccinia virus expressing the HIV-1 env gene. Priming of CTL was also successful when using 16-amino acid lipopeptides as 34-amino acid lipopeptides, suggesting that several epitopes might be included in a single construct. In vivo priming of CTL also requires CD4+ T cell help. We therefore searched for Th cell activation after priming with lipopeptides. Our results show that, as with CTL induction, Th cell activation with lipopeptides did not require mixing with adjuvant. In addition, lipopeptides were also efficient at stimulating antibody-mediated responses. Our results show that a single lipopeptidic construct can induce a total immune response, which is of importance in vaccine development.

We describe the isolation of a synthetic agonist of IFN-gamma (L-mIFN-gamma-CT) active on mouse and human cells. Its biological activity is the result of the ability of the C-terminal extremity of murine IFN-gamma to interact with the intracellular part of IFNgamma-R and the observation that the modification of peptides by a palmitic acid enables their cytoplasmic delivery. L-mIFN-gamma-CT stimulated murine cells exhibited an increase in MHC class II molecules and FcgammaRII/III expression and conferred protection against viral lysis. Unresponsiveness to L-mIFN-gamma-CT of cells recovered from IFNgamma-R alpha-chain knockout mice indicated the involvement of IFNgamma-R in the biological activities observed. Induction of VCAM-1, ICAM-1, and HLA-DR expression on human cells stimulated with L-mIFN-gamma-CT demonstrated an abrogation of species specificity. These results describe the development of a new synthetic agonist of IFN-gamma, which substitutes for the native cytokine in any IFN-gamma responsive cells, by acting intracellularly on IFN-gammaR.We describe the isolation of a synthetic agonist of IFN-gamma (L-mIFN-gamma-CT) active on mouse and human cells. Its biological activity is the result of the ability of the C-terminal extremity of murine IFN-gamma to interact with the intracellular part of IFNgamma-R and the observation that the modification of peptides by a palmitic acid enables their cytoplasmic delivery. L-mIFN-gamma-CT stimulated murine cells exhibited an increase in MHC class II molecules and FcgammaRII/III expression and conferred protection against viral lysis. Unresponsiveness to L-mIFN-gamma-CT of cells recovered from IFNgamma-R alpha-chain knockout mice indicated the involvement of IFNgamma-R in the biological activities observed. Induction of VCAM-1, ICAM-1, and HLA-DR expression on human cells stimulated with L-mIFN-gamma-CT demonstrated an abrogation of species specificity. These results describe the development of a new synthetic agonist of IFN-gamma, which substitutes for the native cytokine in any IFN-gamma responsive cells, by acting intracellularly on IFN-gammaR.

The disulfide-bridge-closed cyclic peptide corresponding to the whole V3 loop of the RF HIV-1 strain was examined by proton two-dimensional NMR spectroscopy in water and water/trifluoroethanol solutions. Although most of the peptide is conformationally averaged in water, the NOE data support a beta-turn conformation for the central conservative GPGR region and the presence of nascent helix. Upon addition of trifluoroethanol, helix formation in the C-terminal part becomes apparent. This is confirmed by CD data. NOEs indicative of multiple and transient beta-turns around the Asn6 glycosylation site and NOEs fitting X-ray data on a linear V3 peptide-Fab complex also emerge. The C-terminal helix is shown to have amphipathic character and might thus assist in the infection process.

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.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.

The P28 antigen of Schistosoma mansoni has been shown to induce protective immunity against schistomiasis in rodents and primates. The analysis of the primary structure of the P28 molecule using various predictive algorithms led to the synthesis of seven peptides which were used to localize the major T cell epitopes of the P28. Two of these synthetic peptides (amino acids 24-43 and 115-131) were found to contain major T cell sites of the P28 antigen. Indeed, both 24-43 and 115-131 peptides stimulate T lymphocytes from Fischer rats and Balb/c mice immunized with the recombinant P28. Moreover, these localized moieties are exposed to the host's immune system during natural S. mansoni infection since they activate T cell populations of infected rats, mice and chronically infected Kenyan children. A multiple antigen peptide containing eight copies of peptide (MAP 115-131) has been prepared and used as immunogen in rats, mice and baboons. In all these models, the MAP 115-131 induces both humoral and cellular responses towards the P28. Preimmunization with the MAP 115-131 before a challenge with the whole P28 molecule increases T cell proliferation and antibody production. The active immunization of rats with the MAP 115-131 before a challenge with the whole P28 molecule increases the T cell proliferation and the antibody production. The active immunization of rats with the MAP 115-131 before challenge infection with the parasite achieved significant protection.