Exploiting antigenic diversity for vaccine design: The chlamydia ArtJ paradigm

Marco Soriani, Pierre Petit, Renata Grifantini, Roberto Petracca, Giovanni Gancitano, Elisabetta Frigimelica, Filomena Nardelli, Christel Garcia, Silvia Spinelli, Guido Scarabelli, Sebastien Fiorucci, Roman Affentranger, Mario Ferrer-Navarro, Martin Zacharias, Giorgio Colombo, Laurent Vuillard, Xavier Daura, Guido Grandi

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33 Citations (Scopus)

Abstract

We present an interdisciplinary approach that, by incorporating a range of experimental and computational techniques, allows the identification and characterization of functional/immunogenic domains. This approach has been applied to ArtJ, an arginine-binding protein whose orthologs in Chlamydiae trachomatis (CT ArtJ) and pneumoniae (CPn ArtJ) are shown to have different immunogenic properties despite a high sequence similarity (60% identity). We have solved the crystallographic structures of CT ArtJ and CPn ArtJ, which are found to display a type II transporter fold organized in two α-β domains with the arginine-binding region at their interface. Although ArtJ is considered to belong to the periplasm, we found that both domains contain regions exposed on the bacterial surface. Moreover, we show that recombinant ArtJ binds to epithelial cells in vitro, suggesting a role for ArtJ in host-cell adhesion during Chlamydia infection. Experimental epitope mapping and computational analysis of physicochemical determinants of antibody recognition revealed that immunogenic epitopes reside mainly in the terminal (D1) domain of both CPn and CT ArtJ, whereas the surface properties of the respective binding-prone regions appear sufficiently different to assume divergent immunogenic behavior. Neutralization assays revealed that sera raised against CPn ArtJ D1 partially reduce both CPn and CT infectivity in vitro, suggesting that functional antibodies directed against this domain may potentially impair chlamydial infectivity. These findings suggest that the approach presented here, combining functional and structure-based analyses of evolutionary-related antigens can be a valuable tool for the identification of cross-species immunogenic epitopes for vaccine development. © 2010 by The American Society for Biochemistry and Molecular Biology, Inc.
Original languageEnglish
Pages (from-to)30126-30138
JournalJournal of Biological Chemistry
Volume285
DOIs
Publication statusPublished - 24 Sep 2010

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