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Protective Effect of Vaccine Promoted Neutralizing Antibodies against the Intracellular Pathogen Chlamydia trachomatis.

ABSTRACT: There is an unmet need for a vaccine to control Chlamydia trachomatis (C.t.) infections. We have recently designed a multivalent heterologous immuno-repeat 1 (Hirep1) vaccine construct based on major outer membrane protein variable domain (VD) 4 regions from C.t. serovars (Svs) D-F. Hirep1 administered in the Cationic Adjuvant Formulation no. 1 (CAF01) promoted neutralizing antibodies in concert with CD4⁺ T cells and protected against genital infection. In the current study, we examined the protective role of the antibody (Ab) response in detail. Mice were vaccinated with either Hirep1 or a vaccine construct based on a homologous multivalent construct of extended VD4's from SvF (extVD4^F*4), adjuvanted in CAF01. Hirep1 and extVD4^F*4 induced similar levels of Ab and cell-mediated immune responses but differed in the fine specificity of the B cell epitopes targeted in the VD4 region. Hirep1 induced a strong response toward a neutralizing epitope (LNPTIAG) and the importance of this epitope for neutralization was demonstrated by competitive inhibition with the corresponding peptide. Immunization with extVD4^F*4 skewed the response to a non-neutralizing epitope slightly upstream in the sequence. Vaccination with Hirep1 as opposed to extVD4^F*4 induced significant protection against infection in mice both in short- and long-term vaccination experiments, signifying a key role for Hirep1 neutralizing antibodies during protection against C.t. Finally, we show that passive immunization of Rag1 knockout mice with Hirep1 antibodies completely prevented the establishment of infection in 48% of the mice, demonstrating an isolated role for neutralizing antibodies in controlling infection. Our data emphasize the role of antibodies in early protection against C.t. and support the inclusion of neutralizing targets in chlamydia vaccines.

SUBMITTER: Olsen AW

PROVIDER: S-EPMC5732375 | biostudies-literature | 2017

REPOSITORIES: biostudies-literature

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Protective Effect of Vaccine Promoted Neutralizing Antibodies against the Intracellular Pathogen Chlamydia trachomatis.

Olsen Anja Weinreich AW Lorenzen Emma Kathrine EK Rosenkrands Ida I Follmann Frank F Andersen Peter P

Frontiers in immunology 20171211

There is an unmet need for a vaccine to control Chlamydia trachomatis (C.t.) infections. We have recently designed a multivalent heterologous immuno-repeat 1 (Hirep1) vaccine construct based on major outer membrane protein variable domain (VD) 4 regions from C.t. serovars (Svs) D-F. Hirep1 administered in the Cationic Adjuvant Formulation no. 1 (CAF01) promoted neutralizing antibodies in concert with CD4+ T cells and protected against genital infection. In the cur ...[more]

PMID: 29312283

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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.

Dataset Information

Protective Effect of Vaccine Promoted Neutralizing Antibodies against the Intracellular Pathogen Chlamydia trachomatis.

Publications

Protective Effect of Vaccine Promoted Neutralizing Antibodies against the Intracellular Pathogen <i>Chlamydia trachomatis</i>.

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