Epitope polarity and adjuvants influence the fine specificity of the humoral response against Semliki Forest virus specific peptide vaccines (original) (raw)
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Journal of virology, 1993
The antibody response to a previously defined B-cell epitope of Semliki Forest virus (SFV) was investigated in male BALB/c (H-2d) mice. The B-cell epitope, located at amino acid positions 240 to 255 of the E2 protein, was linked to an H-2d-restricted T-helper cell epitope of SFV located at positions 137 to 151 of the E2 protein. Colinearly synthesized peptides, of either T-B or B-T polarity, mixed with different adjuvants (the nonionic block copolymer L 180.5, a water-oil-water [W/O/W] emulsion of L 180.5, Montanide, and Q VAC) were used for immunization. Generally, after one booster immunization, high serum antibody titers were measured against either peptide. With Q VAC and W/O/W L 180.5 as adjuvants, the titers of SFV-reactive (nonneutralizing) antibodies were consistently much higher after immunization with the T-B peptide than with the B-T peptide, which was reflected in a higher vaccine efficacy. With these two adjuvants, the survival ratio in T-B peptide-immunized mice was 82...
Journal of General Virology, 1992
A synthetic peptide that contains a Semliki Forest virus (SFV) B cell epitope, located at amino acid positions 240 to 255 of the E2 protein, and an SFV T helper (Th) cell epitope, located at positions 137 to 151 of the E2 protein, evoked high titres of SFV-reactive antibodies in H-2 d mice. Although the peptide-induced antibodies did not neutralize SFV in vitro, 70 to 100% of the peptide-immunized mice were protected against SFV, even when viral challenge was presented 4 months after immunization. The protection could be transferred by anti-peptide serum, indicating that antibodies were responsible for the protection. When the Th cell epitope of this protective peptide was replaced by an influenza virus Th cell epitope or by another SFV Th cell epitope, the resulting peptides induced lower non-neutralizing SFV-reactive antibody titres and protected a correspondingly lower percentage of mice (50% and 30%, respectively). A peptide with the same Th cell epitope as the best protective peptide but with a less effective SFV B cell epitope protected only 33% of the mice. These results indicate that protection against SFV by a synthetic peptide is primarily dependent on its ability to induce adequate amounts of antibodies with relevant specificity and sufficient affinity; the ability to induce a relevant (SFV-specific) T memory response played only a minor role in protection.
Journal of General Virology, 1991
Semliki Forest virus (SFV) infection of mice was used as a model to study the applicability of synthetic peptides containing only linear epitopes as viral vaccines. The identification of linear epitopes with vaccine potential on the E2 membrane protein of SFV was based on the binding of SFV-specific antibodies to a set of overlapping synthetic hexapeptides (Pepscan) representing the whole E2 amino acid sequence. The 14 available E2-specific monoclonal antibodies which were protective in vivo proved to be unsuitable for the identification of linear epitopes because they recognized only conformational epitopes, as indicated by their lack of reactivity with unfolded, reduced E2 protein on immunoblots. Three epitopes were detected with polyclonal anti-SFV serum at amino acid posi-tions 135 to 141,177 to 185 and 240 to 246 of the E2 protein. Synthetic peptides containing these epitopes were coupled to a carrier protein and tested as a vaccine. Mice immunized with the peptide containing amino acids 240 to 255 of protein E2 were protected against a challenge with virulent SFV but protection of mice immunized with the peptides containing amino acids 126 to 141 or 178 to 186 was only marginally better than that of controls. The prechallenge sera of most peptide-immunized mice reacted with SFVinfected cells but none of these sera neutralized the virus in vitro. However, protection of mice correlated well with SFV-specific antibody titre, suggesting antibody-mediated protection.
Immunology, 1992
The rational development of peptide vaccines requires the identification of both B- and T-cell epitopes. In this study, potential T-helper cell epitopes of Semliki Forest virus (SFV) were identified on the basis of their ability to induce delayed-type hypersensitivity (DTH) in mice using recombinant SFV fragments produced as hybrid proteins with beta-galactosidase in Escherichia coli and synthetic peptides coupled to beta-galactosidase. Although the tested fragments spanned almost the entire amino acid sequence of the structural proteins of SFV, only one DTH-inducing region (located between amino acid 137 and 151 of the SFV E2 membrane protein) was identified. Peptides containing this E2 region stimulated lymph node cells from SFV-primed mice in vitro. The ability of the identified T-cell epitope to induce a specific T-helper response in mice was evaluated using synthetic peptides that contained combinations of the DTH-inducing region and different previously identified linear B-cel...
Delineation of protective epitopes on the E2-envelope glycoprotein of Semliki Forest virus
Vaccine, 1991
Two short linear peptides, 17 and 14 amino acids long, on the Semliki Forest virus (SFV) E2-envelope polypeptide are shown to be involved in the protection of mice against lethal challenge with SFV. Peptides corresponding to these two regions, designated H and L, were selected for study on the basis of our model for prediction of protective epitopes on E2 polypeptide of alphaviruses. These peptides were produced in Escherichia coli as recombinant proteins fused to the amino terminus of fl-galactosidase. Both the H epitope (amino acid positions 227-243 on E2) and L epitope (amino acid positions 297-310) are recognized by antibodies raised against SFV, and both trigger antibodies that interact with native SFV-E2. Vaccination of mice with the H-fl-galactosidase polypeptide confers 64-87% protection against a lethal viral challenge (250 LDso), and immunization with L-fl-galactosidase leads to 23-66% protection of challenged mice. The efficacy of the L-based synthetic vaccine could be improved further (up to 100% protection) by presentation of this epitope as a dimer fused to fl-galactosidase. These results provide evidence that the algorithm and the methodology proposed by us previously I"2 are effective tools for identification of linear protective epitopes on E2-envelope of SFV.
Mechanisms of monoclonal antibody-mediated protection against virulent Semliki Forest virus
Journal of virology, 1985
Both neutralizing and nonneutralizing immunoglobulin G2a monoclonal antibodies (MAs) directed against the E2 glycoprotein of Semliki Forest virus (SFV) protected mice prophylactically and therapeutically against virulent SFV infection. The neutralizing MAs, however, conferred protection to mice at lower doses than did nonneutralizing MAs. The antibody-dependent, complement-mediated cytolysis of SFV-infected L cells was effectuated by both kinds of antibodies, but again neutralizing MAs were more effective. Removal of the Fc part of the neutralizing MA UM 5.1 by pepsin digestion resulted in a 100-fold reduction of the neutralization titer (10(4) versus 10(6)) and a complete loss of its capacity to mediate antibody-dependent, complement-mediated cytolysis. Passive protection of infected mice occurred only after administration of relatively high doses of F(ab')2 of MA UM 5.1 (30.0 micrograms versus 0.1 microgram). F(ab')2 fragments prepared from the nonneutralizing MA UM 4.2 ha...
Serologically defined linear epitopes in the E2 envelope glycoprotein of Semliki Forest virus
Archives of Virology, 1990
A set of 41 overlapping peptides, representing the complete sequence of SFV-E2 protein were synthesized and analyzed in the ELISA test against murine anti-SFV sera. No single peptide was recognized by all antisera. Eight peptides were found to be highly reactive with hyperimmune anti-SFV sera. Six out of the eight peptide sequences coincide with the most hydrophilic regions of SFV-E2. Out of these, four peptides (amino acid positions 16-35, 61-80, 166-185, 286-305) that contain the least number of alphavirus conserved residues were selected. This panel constitutes the minimal number of peptides necessary and sufficient for specific recognition of hyperimmune mouse anti-SFV sera.
Journal of virology, 1984
Fifteen monoclonal antibodies (MAs) directed against either the E1 or E2 glycoprotein of Semliki Forest virus (SFV) were characterized by immunoglobulin subclass, pI traject, hemagglutination inhibition, neutralization of infectious virus, and protection against virulent infection in mice. All MAs except UM8.4 (immunoglobulin M [IgM]) belonged to various subclasses of IgG and predominantly to IgG2a, but all were unique as indicated by their banding patterns in isoelectric focusing. Competitive binding assays with these MAs revealed the presence of at least six distinct antigenic determinants (epitopes) on the E1 glycoprotein and five epitopes on the E2 glycoprotein. Two of the epitopes on E1, as defined by the properties of the MAs, were associated with hemagglutination inhibition (E1c and E1d), three were associated with neutralization (E1a, E1b, and E1f), and five were associated in various degrees with protection (E1a, E1b, E1c, E1e, and E1f) of mice against virulent SFV infectio...
Vaccine, 1998
A colinearly synthesized peptide consisting of a H-2d restricted T-helper cell epitope of Semliki Forest virus (SFV) and triple repeats of sequence GPGRAF, derived from the V3 domain of HIV-1 strains, was used to immunize BALB/c (H-2d) mice. Pepscan analysis of sera from peptide-immunized mice revealed that the chimaeric peptide GREKFTIRPHYGKEIGPGRAFGPGRAFGPGRAF contains three distinct antibody-reactive sequences GREKFTIR, PHYGKEI and GPGRAF. The chimaeric peptide evoked HIV-1 IIIb neutralizing antibodies in serum as measured in vitro by reduction of syncytia formation and reduction of p24 production as well. So, the T-helper cell epitope of SFV provided help to a small linear neutralization epitope of HIV-1 strains. Interestingly, the T-helper cell epitope alone might induce antibodies cross-reactive with HIV-1 IIIb specific peptide GPGRAFVTIGK which shows some homology (residues underlined) with the antibody-reactive sequence GREKTIR of SFV.