Profiling of Human Antibody Responses toChlamydia trachomatisUrogenital Tract Infection Using Microplates Arrayed with 156 Chlamydial Fusion Proteins

Abstract

The available chlamydial genome sequences have made it possible to comprehensively analyze host responses to all chlamydial proteins, which is essential for further understanding of chlamydial pathogenesis and development of effective chlamydial vaccines. Microplates arrayed with 156 Chlamydia trachomatis fusion proteins were used to evaluate antibody responses in women urogenitally infected with C. trachomatis. Based on both the antibody recognition frequency and titer, seven chlamydial antigens encoded by open reading frames (ORFs) CT089, CT147, CT226, CT681, CT694, CT795, and CT858, respectively, were identified as relatively immunodominant; six of these are encoded by hypothetical ORFs. Antibody binding to these chlamydial fusion proteins was blocked by C. trachomatis-infected but not by normal HeLa cell lysates or irrelevant bacterial lysates. These results have revealed novel immune-reactive chlamydial antigens, not only indicating that the hypothetical ORF-encoded proteins are expressed during chlamydial infection in humans but also providing the proof of principle that the fusion protein-based approach can be used to profile human immune responses to chlamydial infection at the whole-genome scale.

Approach to discover T- and B-cell antigens of intracellular pathogens applied to the design of Chlamydia trachomatis vaccines

“…Genome/proteome-based highthroughput technologies have been exploited recently to study Chlamydia immunogenic antigens (17)(18)(19)(20)(21)(22)(23)(24)(25)(26). Although the data are not always easily comparable because of the use of different strains, assays, and infected hosts (mice and humans), a Chlamydia immunome atlas can be compiled (Table S3) if one takes as reference the genome annotation of C. trachomatis and combines both mouse and human immunogenic antigens.…”

“…A large body of evidence derived from our understanding of Chlamydia immunity in animal models (13)(14)(15)(16) and in humans (14,17) indicates that both IFN-γ-producing, Chlamydia-specific CD4 + type 1 T helper (Th1) cells and antiChlamydia antibodies are required to mount a protective immune response. A number of chlamydial proteins eliciting CD4 + T cells and/or antibodies have been described (17)(18)(19)(20)(21)(22)(23)(24)(25)(26). However, with few exceptions, they provide only partial protection in animal models, and, in any case, their protective activity is not comparable with the protective immunity induced by infection.…”

“…1 A and B): YebL (CT415), IncA (CT119), YscJ (CT559), EF-Tu (CT322), RplL (CT316), ArtJ (CT381) and the hypothetical proteins CT049, CT355, and CT589. Among the 23 antigens identified as antibody inducers, 15 had never been described before as immunodominant antigens (Tables S1, S2, and S3) (19,20,23,25,26).…”

A Genome-Wide Profiling of the Humoral Immune Response to Chlamydia trachomatis Infection Reveals Vaccine Candidate Antigens Expressed in Humans

“…This vector system allows the protein of interest to be expressed as a fusion protein with the GST fused to the N terminus of the chlamydial proteins (18,30,31). The fusion protein expression was induced with isopropyl-b-Dthiogalactoside (Invitrogen, Carlsbad, CA).…”

CPAF selectively degrades chlamydial T cell antigens for inhibiting antigen presentation

“…GST-fusion recombinant proteins of D111, D628, D622, D702, D509, and D694 were expressed in a pGEX expression system (GST was fused to the N terminus of the chlamydial proteins) and purified by glutathione-conjugated agarose beads (Amersham Biosciences, Pittsburgh, USA) as described previously [41][42][43]. To monitor the processing of chlamydia T cell antigens by CPAF, a cell-free pre-incubation assay was used as described elsewhere [36].…”