Long-Term Multiepitopic Cytotoxic-T-Lymphocyte Responses Induced in Chimpanzees by Combinations ofPlasmodium falciparumLiver-Stage Peptides and Lipopeptides

Abstract

Preclinical immunogenicity studies of 12 malaria peptides, selected from four Plasmodium falciparum antigens (Ags), namely, LSA1, LSA3, SALSA, and STARP, that are expressed at the pre-erythrocytic (sporozoite and liver) stages of the human parasite were carried out in chimpanzees. To strengthen their immunogenicity, six of these synthetic peptides were modified by the C-terminal addition of a single palmitoyl chain (lipopeptides) and delivered without adjuvant, whereas the remaining six unmodified peptides were emulsified and delivered by using Montanide ISA51 adjuvant. We have previously reported that these peptides and lipopeptides induce high B-cell and CD4؉ -T-helper responses in chimpanzees. In this report, we show their ability to induce multiepitopic and long-lasting antigen-specific CD8؉ cytotoxic-T-lymphocyte (CTL) responses. The magnitude, consistency, and memory of CTL responses generated by LSA3 peptides point to the strong immunogenicity of this liver-stage Ag. These findings support the screening strategy used to select the four P. falciparum pre-erythrocytic Ags and emphasize their valuable immunogenic properties. The successful immunization of nonhuman primates with combinations of corresponding peptides in a mineral oil emulsion (ISA51) and lipopeptides in saline provide a vaccine formulation that can be tested in humans.

Th-Cytotoxic T-Lymphocyte Chimeric Epitopes Extended by N ε -Palmitoyl Lysines Induce Herpes Simplex Virus Type 1-Specific Effector CD8 + Tc 1 Responses and Protect against Ocular Infection

“…Construction of these chimeric lipopeptides was carried out using a modified version of the newly described chemoselective ligation method that allows synthesis of high-yield, molecularly pure, and water-soluble molecules (12,18). Unlike the "first generation of lipopeptides" synthesized using classic solid-phase methods which introduce the fatty acyl moiety onto the crude peptide backbone before its purification (4,7,8,13), the lipopeptides employed in this study were constructed in two steps (12,18,43). The first step of synthesis and purification of the peptide backbone was followed by a second step of ligation of the lipid moiety, site-specifically introduced in solution (12,18,43).…”

“…Spleen-derived immune CD8 ϩ T cells were restimulated in vitro with HSV-gB 498-505 target peptide (5 g/ml)-pulsed syngeneic irradiated T-depleted splenocytes as we described previously (2,8). Irradiated EL-4 cells (3,000 rad from a 137 Cs source) were added to the coculture as APC.…”

“…Irradiated EL-4 cells (3,000 rad from a 137 Cs source) were added to the coculture as APC. CTL activity was assessed by a standard 4-h 51 Cr release assay against EL4 target cells loaded with 10 M HSV-gB 498-505 target peptide or infected with heat-inactivated HSV-1 (multiplicity of infection ϭ 3) as described previously (6,8). After 5 days of culture, effector CD8 ϩ cells were mixed at 1, 3, 10, 30, and 100 effector/target (E/T) ratios with 51 Cr-labeled EL4 cells for 4 h. Maximum release of 51 Cr was determined by adding 5% Triton X-100 to 51 Cr-labeled EL4 cells.…”

HLA-A*0201-Restricted CD8+ Cytotoxic T Lymphocyte Epitopes Identified from Herpes Simplex Virus Glycoprotein D

“…Lymphoblastoid cell lines (LCLs) were generated as we (26,29,38) and others have previously described (39). Briefly, LCLs were derived by stimulating PBMCs with PHA (4 g/ml) in RPMI 1640 plus 10% FCS for 3 days.…”

Asymptomatic Human CD4+Cytotoxic T-Cell Epitopes Identified from Herpes Simplex Virus Glycoprotein B

“…Although the high degree of HLA polymorphism is often pointed out as a major hindrance to the use of high-affinity epitope-based vaccines, this constraint can be dealt with through the inclusion of multiple supertype-restricted epitopes, recognized in the context of diverse related HLA alleles, and by designing vaccines with higher epitope densities (5,8,56,80). Thus, an effective vaccine could include multiple "asymptomatic" T-cell epitopes present in diverse herpesvirus protein Ags, chosen to represent at least the HLA-DR supertypes, known to provide recognition in up to 95% of the global population, regardless of race and ethnicity (2,4,6,56).…”