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

ABSTRACT: Natural immunity against obligate and/or facultative intracellular pathogens is usually mediated by both humoral and cellular immunity. The identification of those antigens stimulating both arms of the immune system is instrumental for vaccine discovery. Although high-throughput technologies have been applied for the discovery of antibody-inducing antigens, few examples of their application for T-cell antigens have been reported. We describe how the compilation of the immunome, here defined as the pool of immunogenic antigens inducing T- and B-cell responses in vivo, can lead to vaccine candidates against Chlamydia trachomatis. We selected 120 C. trachomatis proteins and assessed their immunogenicity using two parallel high-throughput approaches. Protein arrays were generated and screened with sera from C. trachomatis-infected patients to identify antibody-inducing antigens. Splenocytes from C. trachomatis-infected mice were stimulated with 79 proteins, and the frequency of antigen-specific CD4(+)/IFN-?(+) T cells was analyzed by flow cytometry. We identified 21 antibody-inducing antigens, 16 CD4(+)/IFN-?(+)-inducing antigens, and five antigens eliciting both types of responses. Assessment of their protective activity in a mouse model of Chlamydia muridarum lung infection led to the identification of seven antigens conferring partial protection when administered with LTK63/CpG adjuvant. Protection was largely the result of cellular immunity as assessed by CD4(+) T-cell depletion. The seven antigens provided robust additive protection when combined in four-antigen combinations. This study paves the way for the development of an effective anti-Chlamydia vaccine and provides a general approach for the discovery of vaccines against other intracellular pathogens.

SUBMITTER: Finco O

PROVIDER: S-EPMC3116399 | biostudies-literature | 2011 Jun

REPOSITORIES: biostudies-literature

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

Finco Oretta O Frigimelica Elisabetta E Buricchi Francesca F Petracca Roberto R Galli Giuliano G Faenzi Elisa E Meoni Eva E Bonci Alessandra A Agnusdei Mauro M Nardelli Filomena F Bartolini Erika E Scarselli Maria M Caproni Elena E Laera Donatello D Zedda Luisanna L Skibinski David D Giovinazzi Serena S Bastone Riccardo R Ianni Elvira E Cevenini Roberto R Grandi Guido G Grifantini Renata R

Proceedings of the National Academy of Sciences of the United States of America 20110531 24

Natural immunity against obligate and/or facultative intracellular pathogens is usually mediated by both humoral and cellular immunity. The identification of those antigens stimulating both arms of the immune system is instrumental for vaccine discovery. Although high-throughput technologies have been applied for the discovery of antibody-inducing antigens, few examples of their application for T-cell antigens have been reported. We describe how the compilation of the immunome, here defined as t ...[more]

PMID: 21628568

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Project description:Background: Chlamydia trachomatis is a prolific human pathogen that can cause serious long-term conditions if left untreated. Recent developments in Chlamydia genetics have opened the door to conducting targeted and random mutagenesis experiments to identify gene function. In the present study, an inducible transposon mutagenesis approach was developed for C. trachomatis using a self-replicating vector to deliver the transposon-transposase cassette - a significant step towards our ultimate aim of achieving saturation mutagenesis of the Chlamydia genome. Methods: The low transformation efficiency of C. trachomatis necessitated the design of a self-replicating vector carrying the transposon mutagenesis cassette (i.e. the Himar-1 transposon containing the beta lactamase gene as well as a hyperactive transposase gene under inducible control of the tet promoter system with the addition of a riboswitch). Chlamydia transformed with this vector (pSW2-RiboA-C9Q) were induced at 24 hours post-infection. Through dual control of transcription and translation, basal expression of transposase was tightly regulated to stabilise the plasmid prior to transposition. Results: Here we present the preliminary sequencing results of transposon mutant pools of both C. trachomatis biovars, using two plasmid-free representatives: urogenital strain C. trachomatis SWFP- and the lymphogranuloma venereum isolate L2(25667R). DNA sequencing libraries were generated and analysed using Oxford Nanopore Technologies' MinION technology. This enabled 'proof of concept' for the methods as an initial low-throughput screen of mutant libraries; the next step is to employ high throughput sequencing to assess saturation mutagenesis. Conclusions: This significant advance provides an efficient method for assaying C. trachomatis gene function and will enable the identification of the essential gene set of C. trachomatis. In the long-term, the methods described herein will add to the growing knowledge of chlamydial infection biology leading to the discovery of novel drug or vaccine targets.

Project description:PurposeChlamydia trachomatis is the leading infectious cause of blindness. The goal of the current study was to search for biomarkers associated with C. trachomatis-induced ocular pathologies.MethodsWe used a whole genome scale proteome array to systematically profile antigen specificities of antibody responses to C. trachomatis infection in individuals from trachoma-endemic communities with or without end-stage trachoma (trichiasis) in The Gambia.ResultsWhen 61 trichiasis patients were compared with their control counterparts for overall antibody reactivity with organisms of different chlamydial species, no statistically significant difference was found. Both groups developed significantly higher titers of antibodies against C. trachomatis ocular serovars A and B than ocular serovar C, genital serovar D, or Chlamydia psittaci, whereas the titers of anti-Chlamydia pneumoniae antibodies were the highest. When antisera from 33 trichiasis and 26 control patients (with relatively high titers of antibodies to C. trachomatis ocular serovars) were reacted with 908 C. trachomatis proteins, 447 antigens were recognized by at least 1 of the 59 antisera, and 10 antigens by 50% or more antisera, the latter being designated as immunodominant antigens. More importantly, four antigens were preferentially recognized by the trichiasis group, with antigens CT414, CT667, and CT706 collectively reacting with 30% of trichiasis antisera but none from the normal group, and antigen CT695 reacting with 61% of trichiasis but only 31% of normal antisera. On the other hand, eight antigens were preferentially recognized by the control group, with antigens CT019, CT117, CT301, CT553, CT556, CT571, and CT709 together reacting with 46% of normal antisera and none from the trichiasis group, whereas antigen CT442 reacted with 35% of normal and 19% of trichiasis antisera respectively.ConclusionsThe current study, by mapping immunodominant C. trachomatis antigens and identifying antigens associated with both ocular pathology and protection, has provided important information for further understanding chlamydial pathogenesis and the development of subunit vaccines.

Project description:Background/aimChlamydia pneumoniae (C. pneumoniae) is implicated in the pathogenesis of Alzheimer's disease (AD). Chlamydial elementary and reticulate bodies have been identified in tissues from afflicted AD brain regions by electron and immunoelectron microscopy, whereas similar tests of non-AD brains were negative for the bacterium. Studies in mice have shown that C. pneumoniae can rapidly penetrate the central nervous system by entering glia and causing beta amyloid deposition via the nerves between the nasal cavity and the brain, which serve as invasion pathways.Materials and methodsWe used data from the UK Biobank (UKBB) to assess the relationship of chlamydia and AD. Circulating C. pneumoniae antigen measurements were not available, but UKBB data field 23037 held measurements of PorB antigen for Chlamydia trachomatis (C. trachomatis). We used C. trachomatis as a surrogate for C. pneumoniae since serum cross-reactivity to C. trachomatis and C. pneumoniae antigens occurs in patients with documented infection and in healthy children as revealed by microimmunofluorescence and immunoblotting techniques. Single nucleotide polymorphism (SNP) data for rs429358 and rs7412 were used to impute ApoE genotypes.ResultsPorB antigen levels for C. trachomatis were significantly higher in subjects with AD (p=0.007). PorB antigen levels were not related to ApoE genotype (e3e3, e3e4, e4e4) p=0.783. To control for the effects of age, sex, educational level, and apoE genotype, logistic regression analysis was performed. AD was the dependent variable. Independent variables were sqrt PorB antigen for C. trachomatis, age, sex, educational level, apoE genotype. AD odds ratio (OR) increased 1.156 for each unit increase of sqrt PorB antigen for C. trachomatis and the effect was significant (p=0.004).ConclusionPorB antigens for C. trachomatis being significantly higher in subjects with AD, corroborates previous studies demonstrating that C. pneumoniae inflammation appears to play a role in AD development. AD may result from the reactivation of embryologic processes and pathways silenced at birth. A trigger for the reactivation may be bacterial or viral infections. Further studies are warranted.

Dataset Information

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

Publications

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

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