Anti-influenza response achieved by immunization with a synthetic conjugate.

Abstract

The peptide corresponding to sequence 91-108 of the hemagglutinin of type A H3N2 influenza virus has been synthesized by the solid-phase peptide synthesis method and covalently attached to several macromolecular carriers. The conjugate with tetanus toxoid was used for immunization ofrabbits and mice. The immunoglobulin fraction of the rabbit antiserum showed the presence of antipeptide antibodies by both agar gel diffusion and radioimmunoassay. In the latter assay, the antibodies showed marked crossreactivity with the intact virus of the A/Texas/77 strain. The antibodies were also capable of inhibiting the hemagglutination of chicken erythrocytes by the virus; the highest hemagglutination inhibition titer (1:32) was achieved with a serumresistant strain of A/Texas/77. When the in vitro virus plaque formation assay was used with monolayers of Madin-Darby canine kidney (MDCK) cells, the number of plaques was reduced on interaction with the immunoglobulin fraction of the antiserum, which was effective up to a dilution of 1:32. Preliminary results indicate that C3H/DiSn mice immunized with the peptide-tetanus toxoid conjugate are partially protected against a further challenge with A/Texas mouse-adapted influenza virus. The results are thus indicative of the efficacy of the synthetic material in eliciting antiinfluenza immune response.The idea of using synthetic materials to replace the vaccines currently used against viruses was put forth several years ago (1, 2). According to this approach, the chemically defined vaccine should contain a unique synthetic antigenic determinant(s) capable of provoking antibodies with neutralizing efficacy against the virus. Although this issue, as discussed recently (3), raises several problems, it also offers many potential advantages and its feasibility for a model virus has been proven. Thus, early studies by Anderer (4) have shown that, by immunizing with a conjugate containing the COOH-terminal hexapeptide of tobacco mosaic virus protein, it is possible to obtain antibodies that interact to some extent with the intact virus. In a more recent study (5), an immunologically active synthetic peptide analogous to a fragment of the coat protein of another virus, MS-2 coliphage, was described. A conjugate containing this peptide provoked antibodies capable of efficiently inactivating the native bacteriophage. It seemed of interest to test this chemical approach in an animal virus system.The influenza virus provides a suitable model for an animal virus for this purpose for the following reasons. (i) Detailed information is available on the structure and function ofthis virus, as well as on its serological specificities and genetic variations.(ii) Various reliable assays of the virus are available (6-9) for evaluating the effect of the immune response on the different viral functions. (iii) Sufficient information is available on the amino acid sequence of the influenza hemagglutinin (10) and on its immunochemical properties (11) to allow the synthesis of a peptide fragment(s) t...

Towards an Epitope-Based Human Vaccine for Influenza

“…The B cell epitope, as mentioned above, comprises the 18-residue peptide corresponding to the sequence HA91-108, which is common to all H3 strains, 35 and is derived from an inner, conserved region of the protein. In earlier studies, this epitope by itself, either conjugated to a macromolecular carrier 36 or expressed in flagella 50 induced partial protection against infection. The amino acids sequence of the T helper epitope that is derived from the viral Nucleoprotein (residues 55-69) is shared by the human infective strains H1N1, H2N2, H3N2 and also by swine (H9N2) specific viruses.…”

“…Moreover, immunization of mice with this conjugate, elicited an in-vivo anti-viral immune response against challenge infection, as observed by the reduced viral load in their lungs. 36,37 In a complementary study, this peptide, that represents a B cell epitope, was either expressed within a carrier protein or anchored to an outer membrane protein proteosome vesicle and used for local (nasal) immunization of mice. When administered without the aid of an adjuvant, it led to a partial in vivo protection.…”

Immunodominant epitopes defined by a yeast-expressed library of random fragments of the rabies virus glycoprotein map outside major antigenic sites

“…This suggests that the corresponding linear epitope, which was characterized with synthetic peptides (Van der Heijden et al, 1993) also belongs to minor antigenic site c. Therefore the peptide strategy indicates as highly immunodominant a region of the G protein which is only recognized by half of our WB + MAbs, a category which represents only 2% of our MAbs. Should this observation be generalized, it would mean that the peptide approach, although it has been successfully used to map some neutralizing epitopes of viral antigens (Muller et al, 1982;Parry et al, 1989;Rini et al, 1993) is not suitable for the characterization of complex major antigenic sites as those of rabies virus G protein.…”

A call to cellular & humoral arms: Enlisting cognate T cell help to develop broad-spectrum vaccines against influenza A

“…Anti-HA antibodies have also been raised to linear determinants: several groups have synthesized short peptides corresponding to sequences in the HA molecule and have tested the ability of these peptides to induce antibodies. [69][70][71] Most antibodies raised to the peptides did not cross-react with antigenic sites on the HA; those that did cross-react did not reduce viral titers or mitigate disease in vivo. 70,71 HA1, the membrane-interacting domain of hemagglutinin, is highly conserved at the sequence level, thus antibodies to this region have been shown to cross react between some subtypes.…”