Characterization of the humoral response induced by a synthetic peptide of the major outer membrane protein of Chlamydia trachomatis serovar B.
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Abstract
The major outer membrane protein of Chlamydia trachomatis has been extensively studied and is still considered one of the most promising candidates for development of a synthetic vaccine. Neutralizing epitopes in variable domains I, II, and IV have already been reported. In variable domain I, residues 69 to 78 have been identified as a neutralizing epitope for some of the C- and C-related complex serovars (A, C, I, J, L3, and K). It is not known whether epitopes located at the same position in B-complex serovars are neutralizing. To clarify this point, rabbit polyclonal antibodies directed against the peptide 69TTTGNAVAPS78 from the B serovar were produced. Rabbit antisera were further rendered peptide specific by purification on a peptide-bovine serum albumin-Sepharose affinity column. Peptide-specific rabbit immunoglobulin reacted with five of the B-complex serovars (B, Ba, E, L1, and L2) by immunoblot and by direct-binding enzyme-linked immunosorbent assay. Furthermore, this peptide-specific rabbit immunoglobulin neutralized the chlamydial infectivity of both serovars B and E for HaK cells in a complement-independent in vitro assay. The importance of these results stems from the fact that peptide 69TTTGNAVAPS78 was able to induce an antibody response directed against B- and B-related complex serovars, including serovar E, which is responsible for a high proportion of genital infections. This peptide could therefore be considered for the construction of a multivalent synthetic vaccine.