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Lu C, Wang J, Zhong G. Preclinical screen for protection efficacy of chlamydial antigens that are immunogenic in humans. Infect Immun 2023; 91:e0034923. [PMID: 37889004 PMCID: PMC10652899 DOI: 10.1128/iai.00349-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2023] [Accepted: 10/02/2023] [Indexed: 10/28/2023] Open
Abstract
To search for subunit vaccine candidates, immunogenic chlamydial antigens identified in humans were evaluated for protection against both infection and pathology in a mouse genital tract infection model under three different immunization regimens. The intramuscular immunization regimen was first used to evaluate 106 chlamydial antigens, which revealed that two antigens significantly reduced while 11 increased genital chlamydial burden. The two infection-reducing antigens failed to prevent pathology and 23 additional antigens even exacerbated pathology. Thus, intranasal mucosal immunization was tested next since intranasal inoculation with live Chlamydia muridarum prevented both genital infection and pathology. Two of the 29 chlamydial antigens evaluated were found to prevent genital infection but not pathology and three exacerbate pathology. To further improve protection efficacy, a combinational regimen (intranasal priming + intramuscular boosting + a third intraperitoneal/subcutaneous boost) was tested. This regimen identified four infection-reducing antigens, but only one of them prevented pathology. Unfortunately, this protective antigen was not advanced further due to its amino acid sequence homology with several human molecules. Two pathology-exacerbating antigens were also found. Nevertheless, intranasal mucosal priming with viable C. muridarum in control groups consistently prevented both genital infection and pathology regardless of the subsequent boosters. Thus, screening 140 different chlamydial antigens with 21 repeated multiple times in 17 experiments failed to identify a subunit vaccine candidate but demonstrated the superiority of viable chlamydial organisms in inducing immunity against both genital infection and pathology, laying the foundation for developing a live-attenuated Chlamydia vaccine.
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Affiliation(s)
- Chunxue Lu
- Institute of Pathogenic Biology, Hengyang Medical College, University of South China, Hengyang, Hunan, China
- Department of Microbiology, Immunology and Molecular Genetics, University of Texas Health Science Center, San Antonio, Texas, USA
| | - Jie Wang
- Department of Microbiology, Immunology and Molecular Genetics, University of Texas Health Science Center, San Antonio, Texas, USA
- Department of Immunology, Xiangya School of Medicine, Central South University, Changsha, Hunan, China
| | - Guangming Zhong
- Department of Microbiology, Immunology and Molecular Genetics, University of Texas Health Science Center, San Antonio, Texas, USA
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A primary Chlamydia trachomatis genital infection of rhesus macaques identifies new immunodominant B-cell antigens. PLoS One 2021; 16:e0250317. [PMID: 33886668 PMCID: PMC8061917 DOI: 10.1371/journal.pone.0250317] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2019] [Accepted: 04/05/2021] [Indexed: 01/09/2023] Open
Abstract
To identify immunodominant antigens that elicit a humoral immune response following a primary and a secondary genital infection, rhesus monkeys were inoculated cervically with Chlamydia trachomatis serovar D. Serum samples were collected and probed with a protein microarray expressing 864/894 (96.4%) of the open reading frames of the C. trachomatis serovar D genome. The antibody response to the primary infection was analyzed in 72 serum samples from 12 inoculated monkeys. The following criteria were utilized to identify immunodominant antigens: proteins found to be recognized by at least 75% (9/12) of the infected monkeys with at least 15% elevations in signal intensity from week 0 to week 8 post infection. All infected monkeys developed Chlamydia specific serum antibodies. Eight proteins satisfied the selection criteria for immunodominant antigens: CT242 (OmpH-like protein), CT541 (mip), CT681 (ompA), CT381 (artJ), CT443 (omcB), CT119 (incA), CT486 (fliY), and CT110 (groEL). Of these, three antigens, CT119, CT486 and CT381, were not previously identified as immunodominant antigens using non-human primate sera. Following the secondary infection, the antibody responses to the eight immunodominant antigens were analyzed and found to be quite different in intensity and duration to the primary infection. In conclusion, these eight immunodominant antigens can now be tested for their ability to identify individuals with a primary C. trachomatis genital infection and to design vaccine strategies to protect against a primary infection with this pathogen.
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Mo J, Li G, Huang G, Wang H, Shi J, Zhou R, Cai G, Wu Z, Zhang X. Adaptation of Gut Microbiome to Transgenic Pigs Secreting β-Glucanase, Xylanase, and Phytase. Front Genet 2021; 12:631071. [PMID: 33747047 PMCID: PMC7971306 DOI: 10.3389/fgene.2021.631071] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2020] [Accepted: 02/10/2021] [Indexed: 11/29/2022] Open
Abstract
We previously generated transgenic pigs with enhanced growth rate and reduced nutrient loss. However, the composition of their gut microbiome is unknown. In this study, we successfully generated EGFP marker-free transgenic (MF-TG) pigs with high expression levels of microbial β-glucanase, xylanase, and phytase in the parotid gland. We collected intestinal contents from the ileum, cecum and colon of five MF-TG and five wild-type (WT) sows and investigated the gut microbiome of the transgenic pigs via metagenomic analysis. Results showed that the levels of probiotics, such as Lactobacillus reuteri and Streptococcus, were more abundant in the cecum of the MF-TG pigs and higher than those of WT pigs. By contrast, the levels of harmful microorganisms, such as Campylobacter, Chlamydia trachomatis, and Campylobacter fetus, and various unidentified viruses, were higher in the cecum of the WT pigs than those of the MF-TG pigs. By comparing unigenes and the eggNOG database, we found that the microorganisms in the colon of the MF-TG pigs had high fractional abundance in DNA (cytosine-5)-methyltransferase 1 and serine-type D-Ala-D-Ala carboxypeptidase, whereas the aspartate carbamoyltransferase regulatory subunit and outer membrane protein pathways were enriched in the WT pigs. Moreover, the microorganisms in the cecum of the MF-TG pigs were active in GlycosylTransferase Family 8 (GT8), Glycoside Hydrolase Family 13 (GH13), and Glycoside Hydrolase Family 32 (GH32). Furthermore, the levels of numerous carbohydrases, such as glucan 1,3-beta-glucosidase, xylan 1,4-beta-xylosidase and exo-1,3-1,4-glucanase, were higher in the cecum of the MF-TG pigs than those of the WT pigs. The results indicated that intestinal microbes can change adaptively to the secretion of transgenic enzymes, thereby forming a benign cooperation with their host. This cooperation could be beneficial for improving feed efficiency.
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Affiliation(s)
- Jianxin Mo
- National Engineering Research Center for Breeding Swine Industry, Wens Foodstuff Group Co., Ltd., Yunfu, China
| | - Guoling Li
- College of Animal Science, South China Agricultural University, Guangzhou, China
| | - Guangyan Huang
- College of Animal Science, South China Agricultural University, Guangzhou, China
| | - Haoqiang Wang
- National Engineering Research Center for Breeding Swine Industry, Wens Foodstuff Group Co., Ltd., Yunfu, China
| | - Junsong Shi
- National Engineering Research Center for Breeding Swine Industry, Wens Foodstuff Group Co., Ltd., Yunfu, China
| | - Rong Zhou
- National Engineering Research Center for Breeding Swine Industry, Wens Foodstuff Group Co., Ltd., Yunfu, China
| | - Gengyuan Cai
- National Engineering Research Center for Breeding Swine Industry, Wens Foodstuff Group Co., Ltd., Yunfu, China.,College of Animal Science, South China Agricultural University, Guangzhou, China
| | - Zhenfang Wu
- National Engineering Research Center for Breeding Swine Industry, Wens Foodstuff Group Co., Ltd., Yunfu, China.,College of Animal Science, South China Agricultural University, Guangzhou, China
| | - Xianwei Zhang
- National Engineering Research Center for Breeding Swine Industry, Wens Foodstuff Group Co., Ltd., Yunfu, China
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Lu C, Sun Z, Chen H, Chen L, Zhu C, Chen C, Li C, Peng B, Zhong G. Proteome array of antibody responses to Chlamydia trachomatis infection in nonhuman primates. Life Sci 2020; 248:117444. [PMID: 32084433 DOI: 10.1016/j.lfs.2020.117444] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2019] [Revised: 02/09/2020] [Accepted: 02/17/2020] [Indexed: 11/29/2022]
Abstract
AIMS Nonhuman primates have been used to investigate pathogenic mechanisms and evaluate immune responses following Chlamydia trachomatis inoculation. This study aimed to systemically profile antibody responses to C. trachomatis infection in nonhuman primates. MATERIALS AND METHODS Sera were obtained from 4 pig-tailed and 8 long-tailed macaques which were intravaginally or ocularly infected with live C. trachomatis organisms, and analyzed by C. trachomatis proteome array of antigens. KEY FINDINGS The sera from 12 macaques recognized total 172 C. trachomatis antigens. While 84 antigens were recognized by pig-tailed macaques intravaginally infected with serovar D strain, 125 antigens were recognized by long-tailed macaques ocularly infected with serovar A, and 37 antigens were recognized by both. Ocular inoculation with virulent A2497 strain induced antibodies to more antigens. Among the antigens uniquely recognized by A2497 strain infected macaques, outer membrane complex B antigen (OmcB) induced robust antibody response. Although macaques infected by less virulent A/HAR-13 strain failed to develop antibodies to OmcB, reinfection by A2497 strain induced high levels of antibodies to OmcB. SIGNIFICANCE Proteome array has revealed a correlation of chlamydial infection invasiveness with chlamydial antigen immunogenicity, and identified antibody responses to OmcB potentially as biomarkers for invasive infection with C. trachomatis.
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Affiliation(s)
- Chunxue Lu
- Institute of Pathogenic Biology, Hengyang Medical College, Hunan Provincial Key Laboratory for Special Pathogens Prevention and Control, University of South China, Hengyang, Hunan 421001, China
| | - Zhenjie Sun
- Institute of Pathogenic Biology, Hengyang Medical College, Hunan Provincial Key Laboratory for Special Pathogens Prevention and Control, University of South China, Hengyang, Hunan 421001, China
| | - Hui Chen
- Institute of Pathogenic Biology, Hengyang Medical College, Hunan Provincial Key Laboratory for Special Pathogens Prevention and Control, University of South China, Hengyang, Hunan 421001, China
| | - Lili Chen
- Institute of Pathogenic Biology, Hengyang Medical College, Hunan Provincial Key Laboratory for Special Pathogens Prevention and Control, University of South China, Hengyang, Hunan 421001, China
| | - Cuiming Zhu
- Institute of Pathogenic Biology, Hengyang Medical College, Hunan Provincial Key Laboratory for Special Pathogens Prevention and Control, University of South China, Hengyang, Hunan 421001, China
| | - Chaoqun Chen
- Institute of Pathogenic Biology, Hengyang Medical College, Hunan Provincial Key Laboratory for Special Pathogens Prevention and Control, University of South China, Hengyang, Hunan 421001, China
| | - Changqing Li
- Nanyue Biopharmaceutical Co. Ltd., Hunan Province Innovative Training Base for Postgraduates, University of South China and Nanyue Biopharmaceutical Co. Ltd., Hengyang, Hunan 421001, China
| | - Bo Peng
- Institute of Pathogenic Biology, Hengyang Medical College, Hunan Provincial Key Laboratory for Special Pathogens Prevention and Control, University of South China, Hengyang, Hunan 421001, China; Department of Pathology, Hengyang Medical College, University of South China, Hengyang, Hunan 421001, China.
| | - Guangming Zhong
- Department of Microbiology, Immunology & Molecular Genetics, University of Texas Health Science Center at San Antonio, San Antonio, TX 78229, USA.
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The Plasmid-Encoded pGP3 Promotes Chlamydia Evasion of Acidic Barriers in Both Stomach and Vagina. Infect Immun 2019; 87:IAI.00844-18. [PMID: 30858342 DOI: 10.1128/iai.00844-18] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2018] [Accepted: 03/06/2019] [Indexed: 02/06/2023] Open
Abstract
Although Chlamydia trachomatis is a human genital tract pathogen, chlamydial organisms have frequently been detected in both vaginal and rectal swab samples of animals and humans. The plasmid-encoded pGP3, a genital tract virulence factor, is essential for Chlamydia muridarum to colonize the mouse gastrointestinal tract. However, intracolon inoculation to bypass the gastric barrier rescued the colonization ability of a pGP3-deficient C. muridarum mutant, suggesting that pGP3 is required for C. muridarum to reach but not to colonize the large intestine. The pGP3-deficient mutant was rapidly cleared in the stomach and was 100-fold more susceptible to gastric killing. In mice genetically deficient in gastrin, a key regulator for gastric acid production, or pharmacologically treated with a proton pump inhibitor, the ability of pGP3-deficient C. muridarum to colonize the gastrointestinal tract was rescued. The pGP3-dependent resistance was further recapitulated in vitro with treatments with HCl, pepsin, or sarkosyl. In the genital tract, deficiency in pGP3 significantly reduced C. muridarum survival in the mouse vagina and increased C. muridarum susceptibility to vaginal killing by ∼8 times. The pGP3-deficient C. muridarum was more susceptible to lactic acid killing, and the pGP3 deficiency also significantly increased C. trachomatis susceptibility to lactic acid. The above-described observations together suggest that Chlamydia may have acquired the plasmid-encoded pGP3 to overcome the gastric barrier during its adaptation to the gastrointestinal tract and the pGP3-dependent resistance may enable chlamydial evasion of the female lower genital tract barrier during sexual transmission.
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Mixed Chlamydia trachomatis Peptide Antigens Provide a Specific and Sensitive Single-Well Colorimetric Enzyme-Linked Immunosorbent Assay for Detection of Human Anti -C. trachomatis Antibodies. mSphere 2018; 3:3/6/e00484-18. [PMID: 30404936 PMCID: PMC6222056 DOI: 10.1128/msphere.00484-18] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
For detection of anti-C. trachomatis antibodies by serological assays, use of classical chlamydial antigens results in high cross-reactivity and poor sensitivity. Previously, we discovered 48 strongly reactive peptide antigens of C. trachomatis-specific B-cell epitopes from 21 immunodominant proteins, and individual testing and combined scoring of 5 to 11 peptide antigens provided highly sensitive and specific detection of anti-C. trachomatis antibodies in chemiluminescent ELISAs. To simplify this method, this study established a single-well labor-saving colorimetric ELISA using a mixture of 12 strongly reactive C. trachomatis peptide antigens (Ctr Mix1) for detection of anti-C. trachomatis antibodies. This Ctr Mix1 ELISA (94% sensitivity and 98% specificity) outperformed 4 commercial ELISAs (49% to 79% sensitivity and 98% specificity). This ELISA can be easily implemented and commercialized, with convenient setup for use in nonspecialized laboratories. Thus, this mixed peptide assay with superior specificity and sensitivity will improve serodiagnosis of C. trachomatis infections. Sensitive and specific detection of anti-Chlamydia trachomatis antibodies in standard enzyme-linked immunosorbent assays (ELISAs) is compromised by cross-reactivity and poor sensitivity of classical C. trachomatis antigens. Previously, we discovered 48 strongly reactive peptide antigens of C. trachomatis-specific B-cell epitopes from 21 immunodominant proteins. By comprehensive individual testing of 11 top-ranked peptide antigens, we found very high sensitivity and specificity for detection of anti-C. trachomatis antibodies in chemiluminescent ELISAs. The current study established a labor-saving colorimetric ELISA by using a mixture of 12 strongly reactive C. trachomatis peptide antigens (Ctr Mix1) in a single well/serum rather than assaying reactivity to each individual peptide. For performance evaluation, we used a simulated population of 212 anti-C. trachomatis antibody-positive and -negative sera from 125 women with NAAT-confirmed active C. trachomatis infection and from 87 healthy women at low risk for C. trachomatis infection. In comparison to a composite reference standard (CRS) for anti-C. trachomatis antibody status, the Ctr Mix1 IgG ELISA achieved 93.9% sensitivity, significantly superior to the 49% to 79% sensitivities of four commercial anti-C. trachomatis IgG ELISAs, and 98% specificity of all tested assays. Compared to the labor-intensive individual peptide testing, this mixed peptide ELISA retained high specificity with only marginal, ∼5% sensitivity loss. By ROC-AUC, likelihood ratio, and predictive value analyses, the Ctr Mix1 ELISA performed satisfactorily at 10% to 75% prevalence range of anti-C. trachomatis antibodies but significantly better than commercial ELISAs. Thus, the labor-saving mixed peptide colorimetric ELISA format provides simultaneously high specificity and sensitivity for detection of anti-C. trachomatis antibodies. IMPORTANCE For detection of anti-C. trachomatis antibodies by serological assays, use of classical chlamydial antigens results in high cross-reactivity and poor sensitivity. Previously, we discovered 48 strongly reactive peptide antigens of C. trachomatis-specific B-cell epitopes from 21 immunodominant proteins, and individual testing and combined scoring of 5 to 11 peptide antigens provided highly sensitive and specific detection of anti-C. trachomatis antibodies in chemiluminescent ELISAs. To simplify this method, this study established a single-well labor-saving colorimetric ELISA using a mixture of 12 strongly reactive C. trachomatis peptide antigens (Ctr Mix1) for detection of anti-C. trachomatis antibodies. This Ctr Mix1 ELISA (94% sensitivity and 98% specificity) outperformed 4 commercial ELISAs (49% to 79% sensitivity and 98% specificity). This ELISA can be easily implemented and commercialized, with convenient setup for use in nonspecialized laboratories. Thus, this mixed peptide assay with superior specificity and sensitivity will improve serodiagnosis of C. trachomatis infections.
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Comprehensive Molecular Serology of Human Chlamydia trachomatis Infections by Peptide Enzyme-Linked Immunosorbent Assays. mSphere 2018; 3:3/4/e00253-18. [PMID: 30068559 PMCID: PMC6070734 DOI: 10.1128/msphere.00253-18] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
For detection of anti-Chlamydia trachomatis antibodies by serological assays, use of classical whole-organism chlamydial antigens results in high cross-reactivity. These antigens bind mainly antibodies against the major outer membrane protein (OmpA) and bind antibodies against other immunodominant non-OmpA proteins to a lesser extent, resulting in poor assay sensitivity. The specificity of C. trachomatis serology is also compromised by the high prevalence of cross-reactive anti-C. pneumoniae antibodies in human populations. We previously identified 48 highly specific C. trachomatis B cell epitope peptide antigens of 21 immunodominant proteins. This study validated peptide antigen-based novel ELISAs that provide highly specific and sensitive detection of anti-C. trachomatis antibodies. Compared to four commercial ELISAs that achieved only poor sensitivities (51.5% to 64.8%), the combined signals of 5 to 11 peptides provided high sensitivity (86.5% to 91.8%) at the same 98% specificity. Thus, by using multiple peptide antigens of immunodominant proteins, we created simple ELISAs with specificity and sensitivity superior to standard C. trachomatis serodiagnosis. Sensitive species-specific detection of anti-Chlamydia trachomatis antibodies is compromised by cross-reactivity of the C. trachomatis antigens used in standard microimmunofluorescence (MIF) testing and enzyme-linked immunosorbent assays (ELISAs). Previously, we discovered 48 strongly reactive C. trachomatis-specific B cell epitope peptides from 21 immunodominant proteins. Here we comprehensively evaluated the 11 top-ranked C. trachomatis-specific peptide antigens from 8 proteins for use in C. trachomatis serology. Sera from 125 women with nucleic acid amplification test (NAAT)-confirmed active C. trachomatis infection and from 49 healthy women with a low risk of C. trachomatis infection were used as anti-C. trachomatis antibody-positive and -negative sera. Results obtained for detection of IgG1, IgG3, and IgA1 antibodies against the 11 C. trachomatis peptide antigens were compared to results from 4 commercial anti-C. trachomatis IgG ELISAs. Using composite reference standards (CRS) of all assays for anti-C. trachomatis antibody status, commercial ELISAs detected antibodies in antibody-positive women with sensitivities of 51.5% to 64.8%. In contrast, a combination of the results of all 11 peptides detected IgG (IgG1 and IgG3) antibodies with 91.8% sensitivity, and a labor-saving combination of the 5 optimal peptides still detected antibodies in antibody-positive women with 86.5% sensitivity (all at 98% specificity). The superior performance of the combined peptide ELISAs was confirmed by area under the receiver operating characteristic curve (ROC-AUC), likelihood ratio, and predictive value analyses. The higher sensitivity of the peptide assays results from using multiple B cell epitopes of several C. trachomatis immunodominant proteins, including OmpA, compared to exclusively using the OmpA antigens used in commercial ELISAs. Thus, ELISAs with combined use of synthetic peptide antigens for C. trachomatis antibody detection have the advantage of simultaneous high sensitivity and high specificity. IMPORTANCE For detection of anti-Chlamydia trachomatis antibodies by serological assays, use of classical whole-organism chlamydial antigens results in high cross-reactivity. These antigens bind mainly antibodies against the major outer membrane protein (OmpA) and bind antibodies against other immunodominant non-OmpA proteins to a lesser extent, resulting in poor assay sensitivity. The specificity of C. trachomatis serology is also compromised by the high prevalence of cross-reactive anti-C. pneumoniae antibodies in human populations. We previously identified 48 highly specific C. trachomatis B cell epitope peptide antigens of 21 immunodominant proteins. This study validated peptide antigen-based novel ELISAs that provide highly specific and sensitive detection of anti-C. trachomatis antibodies. Compared to four commercial ELISAs that achieved only poor sensitivities (51.5% to 64.8%), the combined signals of 5 to 11 peptides provided high sensitivity (86.5% to 91.8%) at the same 98% specificity. Thus, by using multiple peptide antigens of immunodominant proteins, we created simple ELISAs with specificity and sensitivity superior to standard C. trachomatis serodiagnosis.
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Woodhall SC, Gorwitz RJ, Migchelsen SJ, Gottlieb SL, Horner PJ, Geisler WM, Winstanley C, Hufnagel K, Waterboer T, Martin DL, Huston WM, Gaydos CA, Deal C, Unemo M, Dunbar JK, Bernstein K. Advancing the public health applications of Chlamydia trachomatis serology. THE LANCET. INFECTIOUS DISEASES 2018; 18:e399-e407. [PMID: 29983342 DOI: 10.1016/s1473-3099(18)30159-2] [Citation(s) in RCA: 45] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/05/2017] [Revised: 02/04/2018] [Accepted: 02/09/2018] [Indexed: 12/22/2022]
Abstract
Genital Chlamydia trachomatis infection is the most commonly diagnosed sexually transmitted infection. Trachoma is caused by ocular infection with C trachomatis and is the leading infectious cause of blindness worldwide. New serological assays for C trachomatis could facilitate improved understanding of C trachomatis epidemiology and prevention. C trachomatis serology offers a means of investigating the incidence of chlamydia infection and might be developed as a biomarker of scarring sequelae, such as pelvic inflammatory disease. Therefore, serological assays have potential as epidemiological tools to quantify unmet need, inform service planning, evaluate interventions including screening and treatment, and to assess new vaccine candidates. However, questions about the performance characteristics and interpretation of C trachomatis serological assays remain, which must be addressed to advance development within this field. In this Personal View, we explore the available information about C trachomatis serology and propose several priority actions. These actions involve development of target product profiles to guide assay selection and assessment across multiple applications and populations, establishment of a serum bank to facilitate assay development and evaluation, and development of technical and statistical methods for assay evaluation and analysis of serological findings. The field of C trachomatis serology will benefit from collaboration across the public health community to align technological developments with their potential applications.
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Affiliation(s)
- Sarah C Woodhall
- Blood Safety, Hepatitis, Sexually Transmitted Infections (STI) and HIV Service, Public Health England, London, UK; National Institute for Health Research Health Protection Research Unit in Evaluation of Interventions, University of Bristol, Bristol, UK; National Institute for Health Research Health Protection Research Unit in Blood Borne and Sexually Transmitted Infections, University College London, London, UK.
| | - Rachel J Gorwitz
- Division of STD Prevention, US Centers for Disease Control and Prevention, Atlanta, GA, USA
| | - Stephanie J Migchelsen
- Blood Safety, Hepatitis, Sexually Transmitted Infections (STI) and HIV Service, Public Health England, London, UK; Clinical Research Department, London School of Hygiene & Tropical Medicine, London, UK
| | - Sami L Gottlieb
- Department of Reproductive Health and Research, World Health Organization, Geneva, Switzerland
| | - Patrick J Horner
- National Institute for Health Research Health Protection Research Unit in Evaluation of Interventions, University of Bristol, Bristol, UK; Population Health Sciences, University of Bristol, Bristol, UK
| | - William M Geisler
- Division of Infectious Diseases, University of Alabama at Birmingham, Birmingham, AL, USA
| | | | - Katrin Hufnagel
- Division of Molecular Diagnostics of Oncogenic Infections, German Cancer Research Center (DKFZ), Heidelberg, Germany
| | - Tim Waterboer
- Division of Molecular Diagnostics of Oncogenic Infections, German Cancer Research Center (DKFZ), Heidelberg, Germany
| | - Diana L Martin
- Division of Parasitic Diseases and Malaria, US Centers for Disease Control and Prevention, Atlanta, GA, USA
| | - Wilhelmina M Huston
- School of Life Sciences, University of Technology Sydney, Sydney, NSW, Australia
| | - Charlotte A Gaydos
- Division of Infectious Diseases, Johns Hopkins University, Baltimore, MD, USA
| | - Carolyn Deal
- Division of Microbiology and Infectious Diseases, National Institute of Health, Bethesda, MD, USA
| | - Magnus Unemo
- WHO Collaborating Centre for Gonorrhoea and Other Sexually Transmitted Infections, Örebro University, Örebro, Sweden
| | - J Kevin Dunbar
- Blood Safety, Hepatitis, Sexually Transmitted Infections (STI) and HIV Service, Public Health England, London, UK; National Institute for Health Research Health Protection Research Unit in Evaluation of Interventions, University of Bristol, Bristol, UK; National Institute for Health Research Health Protection Research Unit in Blood Borne and Sexually Transmitted Infections, University College London, London, UK
| | - Kyle Bernstein
- Division of STD Prevention, US Centers for Disease Control and Prevention, Atlanta, GA, USA
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Update on Chlamydia trachomatis Vaccinology. CLINICAL AND VACCINE IMMUNOLOGY : CVI 2017; 24:CVI.00543-16. [PMID: 28228394 DOI: 10.1128/cvi.00543-16] [Citation(s) in RCA: 71] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Attempts to produce a vaccine to protect against Chlamydia trachomatis-induced trachoma were initiated more than 100 years ago and continued for several decades. Using whole organisms, protective responses were obtained. However, upon exposure to C. trachomatis, disease exacerbation developed in some immunized individuals, precluding the implementation of the vaccine. Evidence of the role of C. trachomatis as a sexually transmitted pathogen started to emerge in the 1960s, and it soon became evident that it can cause acute infections and long-term sequelae in women, men, and newborns. The main focus of this minireview is to summarize recent findings and discuss formulations, including antigens, adjuvants, routes, and delivery systems for immunization, primarily explored in the female mouse model, with the goal of implementing a vaccine against C. trachomatis genital infections.
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Pickering H, Burr SE, Derrick T, Makalo P, Joof H, Hayward RD, Holland MJ. Profiling and validation of individual and patterns of Chlamydia trachomatis-specific antibody responses in trachomatous trichiasis. Parasit Vectors 2017; 10:143. [PMID: 28288672 PMCID: PMC5347170 DOI: 10.1186/s13071-017-2078-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2016] [Accepted: 03/06/2017] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Ocular Chlamydia trachomatis (Ct) infection causes trachoma, the leading infectious cause of blindness. A Ct D/UW3 proteome microarray and sera from Gambian adults with trachomatous trichiasis (TT) or healthy matched controls previously identified several novel antigens, which suggested differential recognition in adults with TT. METHODS We re-analysed this serological microarray data using more robust microarray analysis techniques accounting for typical problems associated with highly dimensional data. We examined the Ct-specific antibody profile concerning the overall diversity of responses, antigen expression stage and cellular localisation of antigens. We tested differentially recognised antigens by further serological testing of the screened sera and used larger independent sample sets for validation. RESULTS Antibody responses identified High-Performance on antigens expressed early and late in the Ct developmental cycle and those secreted or localised to the outer membrane. Eight antigens were preferentially recognised by scarred individuals and one antigen by healthy individuals. Three of these antigens, two associated with scarring (CT667 and CT706) and one healthy-associated (CT442), were not associated with the presence or absence of scarring following specific serological testing of the arrayed sera and sera from larger, independent case-control cohorts. CONCLUSIONS This study identified focussed Ct-specific antibody profiles targeting proteins expressed during entry and exit from cells and localised to interact with the host. A small panel of antibody responses could discriminate between adults with and without TT in a trachoma-endemic community. Heterogenous responses in the independent validation of these antibody targets highlighted the need for large sample sizes, clearly defined clinical phenotypes and follow-up work.
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Affiliation(s)
- Harry Pickering
- Clinical Research Department, London School of Hygiene and Tropical Medicine, Keppel Street, London, UK.
| | - Sarah E Burr
- Disease Control and Elimination Theme, Medical Research Council, The Gambia Unit, Fajara, Banjul, Gambia
| | - Tamsyn Derrick
- Clinical Research Department, London School of Hygiene and Tropical Medicine, Keppel Street, London, UK
| | - Pateh Makalo
- Disease Control and Elimination Theme, Medical Research Council, The Gambia Unit, Fajara, Banjul, Gambia
| | - Hassan Joof
- Disease Control and Elimination Theme, Medical Research Council, The Gambia Unit, Fajara, Banjul, Gambia
| | - Richard D Hayward
- Institute of Structural and Molecular Biology, Birkbeck and University College London, Malet Street, London, UK
| | - Martin J Holland
- Clinical Research Department, London School of Hygiene and Tropical Medicine, Keppel Street, London, UK
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11
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Zhong G. Chlamydial Plasmid-Dependent Pathogenicity. Trends Microbiol 2016; 25:141-152. [PMID: 27712952 DOI: 10.1016/j.tim.2016.09.006] [Citation(s) in RCA: 72] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2016] [Revised: 09/11/2016] [Accepted: 09/19/2016] [Indexed: 10/20/2022]
Abstract
Most Chlamydia species carry a 7.5kb plasmid encoding eight open reading frames conventionally called plasmid glycoproteins 1-8 or pGP1-8. Although the plasmid is not critical for chlamydial growth in vitro, its role in chlamydial pathogenesis is clearly demonstrated in the genital tracts of mice infected with Chlamydia muridarum, a model for investigating the human pathogen Chlamydia trachomatis. Plasmid-free C. trachomatis is also attenuated in both the mouse genital tract and nonhuman primate ocular tissue. Deficiency in pGP3 alone, which is regulated by pGP4, largely reproduced the in vivo but not in vitro phenotypes of the plasmid-free organisms, suggesting that pGP3 is a key in vivo virulence factor. The positive and negative regulations of some chromosomal genes by pGP4 and pGP5, respectively, may allow the plasmid to promote chlamydial adaptation to varied animal tissue environments. The focus of this review is to summarize the progress on the pathogenic functions of the plasmid-encoded open reading frames, which may motivate further investigation of the molecular mechanisms of chlamydial pathogenicity and development of medical utility of the chlamydial plasmid system.
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Affiliation(s)
- Guangming Zhong
- Department of Microbiology and Immunology, University of Texas Health Science Center at San Antonio, 7703 Floyd Curl Drive, San Antonio, TX 78229, USA.
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12
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Mihailovic J, Inic-Kanada A, Smiljanic K, Stein E, Barisani-Asenbauer T, Cirkovic Velickovic T. Lysine acetylation of major Chlamydia trachomatis antigens. EUPA OPEN PROTEOMICS 2016; 10:63-69. [PMID: 29900103 PMCID: PMC5988610 DOI: 10.1016/j.euprot.2016.01.007] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/28/2015] [Revised: 01/06/2016] [Accepted: 01/25/2016] [Indexed: 11/05/2022]
Abstract
Chlamydia trachomatis causes trachoma and sexually transmitted diseases. Molecular mechanisms of chlamydial pathogenesis and immunity remain unclear. Acetylation of lysine is a post-translational modification that occurs in prokaryotes. Lysine acetylation sites were discovered in major chlamydial antigens. 60 kDa chaperonin, EF-G and PmpB showed the highest degree of acetylation.
Chlamydia trachomatis (Ct) is a human pathogen causing trachoma and infertility. We investigated acetylation at lysine residues of chlamydial antigenic proteins: major outer membrane protein (MOMP), 60 kDa chaperonin (chlamydial Hsp60), elongation factor G (EF-G), enolase and the polymorphic membrane proteins PmpB, PmpE and PmpF. 60 kDa chaperonin, EF-G and PmpB showed the highest degree of acetylation. Our data show that important Ct antigens could be post-translationally modified by acetylation of lysine residues at multiple sites. Further studies are needed to investigate total acetylome of Ct and the impact PTMs might have on Ct biology and pathogenicity.
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Affiliation(s)
- Jelena Mihailovic
- Center of Excellence for Molecular Food Sciences and Department of Biochemistry, University of BelgradeFaculty of Chemistry, Belgrade, Serbia
| | - Aleksandra Inic-Kanada
- OCUVACCenter of Ocular Inflammation and Infection, Laura Bassi Centers of Expertise, Center for Pathophysiology, Infectiology and Immunology, Medical University of Vienna, Vienna, Austria
| | - Katarina Smiljanic
- Center of Excellence for Molecular Food Sciences and Department of Biochemistry, University of BelgradeFaculty of Chemistry, Belgrade, Serbia
| | - Elisabeth Stein
- OCUVACCenter of Ocular Inflammation and Infection, Laura Bassi Centers of Expertise, Center for Pathophysiology, Infectiology and Immunology, Medical University of Vienna, Vienna, Austria
| | - Talin Barisani-Asenbauer
- OCUVACCenter of Ocular Inflammation and Infection, Laura Bassi Centers of Expertise, Center for Pathophysiology, Infectiology and Immunology, Medical University of Vienna, Vienna, Austria
| | - Tanja Cirkovic Velickovic
- Center of Excellence for Molecular Food Sciences and Department of Biochemistry, University of BelgradeFaculty of Chemistry, Belgrade, Serbia
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13
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Murthy AK, Li W, Ramsey KH. Immunopathogenesis of Chlamydial Infections. Curr Top Microbiol Immunol 2016; 412:183-215. [PMID: 27370346 DOI: 10.1007/82_2016_18] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Chlamydial infections lead to a number of clinically relevant diseases and induce significant morbidity in human populations. It is generally understood that certain components of the host immune response to infection also mediate such disease pathologies. A clear understanding of pathogenic mechanisms will enable us to devise better preventive and/or intervention strategies to mitigate the morbidity caused by these infections. Over the years, numerous studies have been conducted to explore the immunopathogenic mechanisms of Chlamydia-induced diseases of the eye, reproductive tract, respiratory tract, and cardiovascular systems. In this article, we provide an overview of the diseases caused by Chlamydia, animal models used to study disease pathology, and a historical context to the efforts to understand chlamydial pathogenesis. Furthermore, we discuss recent findings regarding pathogenesis, with an emphasis on the role of the adaptive immune response in the development of chlamydial disease sequelae. Finally, we summarize the key insights obtained from studies of chlamydial pathogenesis and avenues that remain to be explored in order to inform the next steps of vaccine development against chlamydial infections.
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Affiliation(s)
- Ashlesh K Murthy
- Department of Pathology, Midwestern University, 555, 31st Steet, Downers Grove, IL, 60515, USA.
| | - Weidang Li
- Department of Pathology, Midwestern University, 555, 31st Steet, Downers Grove, IL, 60515, USA
| | - Kyle H Ramsey
- Department of Microbiology and Immunology, Midwestern University, Downers Grove, IL, 60515, USA
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14
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Inic-Kanada A, Stojanovic M, Schlacher S, Stein E, Belij-Rammerstorfer S, Marinkovic E, Lukic I, Montanaro J, Schuerer N, Bintner N, Kovacevic-Jovanovic V, Krnjaja O, Mayr UB, Lubitz W, Barisani-Asenbauer T. Delivery of a Chlamydial Adhesin N-PmpC Subunit Vaccine to the Ocular Mucosa Using Particulate Carriers. PLoS One 2015; 10:e0144380. [PMID: 26656797 PMCID: PMC4684359 DOI: 10.1371/journal.pone.0144380] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2015] [Accepted: 11/17/2015] [Indexed: 11/18/2022] Open
Abstract
Trachoma, caused by the intracellular bacterium Chlamydia trachomatis (Ct), remains the world's leading preventable infectious cause of blindness. Recent attempts to develop effective vaccines rely on modified chlamydial antigen delivery platforms. As the mechanisms engaged in the pathology of the disease are not fully understood, designing a subunit vaccine specific to chlamydial antigens could improve safety for human use. We propose the delivery of chlamydia-specific antigens to the ocular mucosa using particulate carriers, bacterial ghosts (BGs). We therefore characterized humoral and cellular immune responses after conjunctival and subcutaneous immunization with a N-terminal portion (amino acid 1-893) of the chlamydial polymorphic membrane protein C (PmpC) of Ct serovar B, expressed in probiotic Escherichia coli Nissle 1917 bacterial ghosts (EcN BGs) in BALB/c mice. Three immunizations were performed at two-week intervals, and the immune responses were evaluated two weeks after the final immunization in mice. In a guinea pig model of ocular infection animals were immunized in the same manner as the mice, and protection against challenge was assessed two weeks after the last immunization. N-PmpC was successfully expressed within BGs and delivery to the ocular mucosa was well tolerated without signs of inflammation. N-PmpC-specific mucosal IgA levels in tears yielded significantly increased levels in the group immunized via the conjunctiva compared with the subcutaneously immunized mice. Immunization with N-PmpC EcN BGs via both immunization routes prompted the establishment of an N-PmpC-specific IFNγ immune response. Immunization via the conjunctiva resulted in a decrease in intensity of the transitional inflammatory reaction in conjunctiva of challenged guinea pigs compared with subcutaneously and non-immunized animals. The delivery of the chlamydial subunit vaccine to the ocular mucosa using a particulate carrier, such as BGs, induced both humoral and cellular immune responses. Further investigations are needed to improve the immunization scheme and dosage.
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Affiliation(s)
- Aleksandra Inic-Kanada
- OCUVAC–Center of Ocular Inflammation and Infection, Laura Bassi Centers of Expertise, Center for Pathophysiology, Infectiology and Immunology, Medical University of Vienna, Vienna, Austria
| | - Marijana Stojanovic
- Department of Research and Development, Institute of Virology, Vaccines and Sera–TORLAK, Belgrade, Serbia
| | - Simone Schlacher
- OCUVAC–Center of Ocular Inflammation and Infection, Laura Bassi Centers of Expertise, Center for Pathophysiology, Infectiology and Immunology, Medical University of Vienna, Vienna, Austria
| | - Elisabeth Stein
- OCUVAC–Center of Ocular Inflammation and Infection, Laura Bassi Centers of Expertise, Center for Pathophysiology, Infectiology and Immunology, Medical University of Vienna, Vienna, Austria
| | - Sandra Belij-Rammerstorfer
- OCUVAC–Center of Ocular Inflammation and Infection, Laura Bassi Centers of Expertise, Center for Pathophysiology, Infectiology and Immunology, Medical University of Vienna, Vienna, Austria
| | - Emilija Marinkovic
- Department of Research and Development, Institute of Virology, Vaccines and Sera–TORLAK, Belgrade, Serbia
| | - Ivana Lukic
- Department of Research and Development, Institute of Virology, Vaccines and Sera–TORLAK, Belgrade, Serbia
| | - Jacqueline Montanaro
- OCUVAC–Center of Ocular Inflammation and Infection, Laura Bassi Centers of Expertise, Center for Pathophysiology, Infectiology and Immunology, Medical University of Vienna, Vienna, Austria
| | - Nadine Schuerer
- OCUVAC–Center of Ocular Inflammation and Infection, Laura Bassi Centers of Expertise, Center for Pathophysiology, Infectiology and Immunology, Medical University of Vienna, Vienna, Austria
| | - Nora Bintner
- OCUVAC–Center of Ocular Inflammation and Infection, Laura Bassi Centers of Expertise, Center for Pathophysiology, Infectiology and Immunology, Medical University of Vienna, Vienna, Austria
| | - Vesna Kovacevic-Jovanovic
- Department of Research and Development, Institute of Virology, Vaccines and Sera–TORLAK, Belgrade, Serbia
| | - Ognjen Krnjaja
- Department of Research and Development, Institute of Virology, Vaccines and Sera–TORLAK, Belgrade, Serbia
| | | | | | - Talin Barisani-Asenbauer
- OCUVAC–Center of Ocular Inflammation and Infection, Laura Bassi Centers of Expertise, Center for Pathophysiology, Infectiology and Immunology, Medical University of Vienna, Vienna, Austria
- * E-mail:
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15
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Derrick T, Roberts CH, Last AR, Burr SE, Holland MJ. Trachoma and Ocular Chlamydial Infection in the Era of Genomics. Mediators Inflamm 2015; 2015:791847. [PMID: 26424969 PMCID: PMC4573990 DOI: 10.1155/2015/791847] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2015] [Accepted: 08/05/2015] [Indexed: 12/19/2022] Open
Abstract
Trachoma is a blinding disease usually caused by infection with Chlamydia trachomatis (Ct) serovars A, B, and C in the upper tarsal conjunctiva. Individuals in endemic regions are repeatedly infected with Ct throughout childhood. A proportion of individuals experience prolonged or severe inflammatory episodes that are known to be significant risk factors for ocular scarring in later life. Continued scarring often leads to trichiasis and in-turning of the eyelashes, which causes pain and can eventually cause blindness. The mechanisms driving the chronic immunopathology in the conjunctiva, which largely progresses in the absence of detectable Ct infection in adults, are likely to be multifactorial. Socioeconomic status, education, and behavior have been identified as contributing to the risk of scarring and inflammation. We focus on the contribution of host and pathogen genetic variation, bacterial ecology of the conjunctiva, and host epigenetic imprinting including small RNA regulation by both host and pathogen in the development of ocular pathology. Each of these factors or processes contributes to pathogenic outcomes in other inflammatory diseases and we outline their potential role in trachoma.
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Affiliation(s)
- Tamsyn Derrick
- Department of Clinical Research, Faculty of Infectious Tropical Diseases, London School of Hygiene and Tropical Medicine, London WC1E 7HT, UK
| | - Chrissy h. Roberts
- Department of Clinical Research, Faculty of Infectious Tropical Diseases, London School of Hygiene and Tropical Medicine, London WC1E 7HT, UK
| | - Anna R. Last
- Department of Clinical Research, Faculty of Infectious Tropical Diseases, London School of Hygiene and Tropical Medicine, London WC1E 7HT, UK
| | - Sarah E. Burr
- Department of Clinical Research, Faculty of Infectious Tropical Diseases, London School of Hygiene and Tropical Medicine, London WC1E 7HT, UK
| | - Martin J. Holland
- Department of Clinical Research, Faculty of Infectious Tropical Diseases, London School of Hygiene and Tropical Medicine, London WC1E 7HT, UK
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16
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Defining species-specific immunodominant B cell epitopes for molecular serology of Chlamydia species. CLINICAL AND VACCINE IMMUNOLOGY : CVI 2015; 22:539-52. [PMID: 25761461 DOI: 10.1128/cvi.00102-15] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/23/2015] [Accepted: 03/09/2015] [Indexed: 11/20/2022]
Abstract
Urgently needed species-specific enzyme-linked immunosorbent assays (ELISAs) for the detection of antibodies against Chlamydia spp. have been elusive due to high cross-reactivity of chlamydial antigens. To identify Chlamydia species-specific B cell epitopes for such assays, we ranked the potential epitopes of immunodominant chlamydial proteins that are polymorphic among all Chlamydia species. High-scoring peptides were synthesized with N-terminal biotin, followed by a serine-glycine-serine-glycine spacer, immobilized onto streptavidin-coated microtiter plates, and tested with mono-specific mouse hyperimmune sera against each Chlamydia species in chemiluminescent ELISAs. For each of nine Chlamydia species, three to nine dominant polymorphic B cell epitope regions were identified on OmpA, CT618, PmpD, IncA, CT529, CT442, IncG, Omp2, TarP, and IncE proteins. Peptides corresponding to 16- to 40-amino-acid species-specific sequences of these epitopes reacted highly and with absolute specificity with homologous, but not heterologous, Chlamydia monospecies-specific sera. Host-independent reactivity of such epitopes was confirmed by testing of six C. pecorum-specific peptides from five proteins with C. pecorum-reactive sera from cattle, the natural host of C. pecorum. The probability of cross-reactivity of peptide antigens from closely related chlamydial species or strains correlated with percent sequence identity and declined to zero at <50% sequence identity. Thus, phylograms of B cell epitope regions predict the specificity of peptide antigens for rational use in the genus-, species-, or serovar-specific molecular serology of Chlamydia spp. We anticipate that these peptide antigens will improve chlamydial serology by providing easily accessible assays to nonspecialist laboratories. Our approach also lends itself to the identification of relevant epitopes of other microbial pathogens.
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17
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Bachmann NL, Polkinghorne A, Timms P. Chlamydia genomics: providing novel insights into chlamydial biology. Trends Microbiol 2014; 22:464-72. [PMID: 24882432 DOI: 10.1016/j.tim.2014.04.013] [Citation(s) in RCA: 65] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2014] [Revised: 04/18/2014] [Accepted: 04/28/2014] [Indexed: 12/12/2022]
Abstract
Chlamydiaceae are obligate intracellular pathogens that have successfully evolved to colonize a diverse range of hosts. There are currently 11 described species of Chlamydia, most of which have a significant impact on the health of humans or animals. Expanding chlamydial genome sequence information has revolutionized our understanding of chlamydial biology, including aspects of their unique lifecycle, host-pathogen interactions, and genetic differences between Chlamydia strains associated with different host and tissue tropisms. This review summarizes the major highlights of chlamydial genomics and reflects on the considerable impact these have had on understanding the biology of chlamydial pathogens and the changing nature of genomics tools in the 'post-genomics' era.
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Affiliation(s)
- Nathan L Bachmann
- Faculty of Science, Health, Education and Engineering, University of the Sunshine Coast, Sippy Downs, Queensland 4558, Australia
| | - Adam Polkinghorne
- Faculty of Science, Health, Education and Engineering, University of the Sunshine Coast, Sippy Downs, Queensland 4558, Australia
| | - Peter Timms
- Faculty of Science, Health, Education and Engineering, University of the Sunshine Coast, Sippy Downs, Queensland 4558, Australia.
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18
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Mabey DCW, Hu V, Bailey RL, Burton MJ, Holland MJ. Towards a safe and effective chlamydial vaccine: lessons from the eye. Vaccine 2014; 32:1572-8. [PMID: 24606636 PMCID: PMC3991328 DOI: 10.1016/j.vaccine.2013.10.016] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2013] [Revised: 09/24/2013] [Accepted: 10/03/2013] [Indexed: 02/06/2023]
Abstract
As well as being the most common bacterial sexually transmitted infection, Chlamydia trachomatis (Ct) is the leading infectious cause of blindness. The pathogenesis of ocular chlamydial infection (trachoma) is similar to that of genital infection. In the 1960s the efficacy of Ct vaccines against ocular infection was evaluated in major field trials in Saudi Arabia, Taiwan, The Gambia, India and Ethiopia. These trials showed that it was possible to induce short term immunity to ocular infection, and to reduce the incidence of inflammatory trachoma, by parenteral immunisation with killed or live whole organism vaccines. In one study, it was also shown that the incidence of scarring sequelae was reduced in vaccinated children. Detailed studies in non-human primates conducted at this time suggested that vaccination could lead to more severe inflammatory disease on subsequent challenge. Since that time there have been many studies on the immunological correlates of protective immunity and immunopathology in ocular Ct infection in humans and non-human primates, and on host genetic polymorphisms associated with protection from adverse sequelae. These have provided important information to guide the development and evaluation of a human Ct vaccine.
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Affiliation(s)
- David C W Mabey
- Department of Clinical Research, Faculty of Infectious and Tropical Diseases, London School of Hygiene & Tropical Medicine, United Kingdom.
| | - Victor Hu
- Department of Clinical Research, Faculty of Infectious and Tropical Diseases, London School of Hygiene & Tropical Medicine, United Kingdom
| | - Robin L Bailey
- Department of Clinical Research, Faculty of Infectious and Tropical Diseases, London School of Hygiene & Tropical Medicine, United Kingdom
| | - Matthew J Burton
- Department of Clinical Research, Faculty of Infectious and Tropical Diseases, London School of Hygiene & Tropical Medicine, United Kingdom
| | - Martin J Holland
- Department of Clinical Research, Faculty of Infectious and Tropical Diseases, London School of Hygiene & Tropical Medicine, United Kingdom
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19
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A Conrad T, Yang Z, Ojcius D, Zhong G. A path forward for the chlamydial virulence factor CPAF. Microbes Infect 2013; 15:1026-32. [PMID: 24141088 DOI: 10.1016/j.micinf.2013.09.008] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2013] [Revised: 08/26/2013] [Accepted: 09/02/2013] [Indexed: 12/14/2022]
Abstract
CPAF is a conserved and secreted protease from obligate intracellular bacteria of the order Chlamydiales. Recently, it was demonstrated that most of its host targets are an artifact of inaccurate methods. This review aims to summarize key features of CPAF and propose new approaches for evaluating its role in chlamydial pathogenesis.
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Affiliation(s)
- Turner A Conrad
- Department of Microbiology and Immunology, University of Texas Health Science Center San Antonio, San Antonio, TX 78229, USA
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20
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Antibody signature of spontaneous clearance of Chlamydia trachomatis ocular infection and partial resistance against re-challenge in a nonhuman primate trachoma model. PLoS Negl Trop Dis 2013; 7:e2248. [PMID: 23738030 PMCID: PMC3667776 DOI: 10.1371/journal.pntd.0002248] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2013] [Accepted: 04/18/2013] [Indexed: 11/19/2022] Open
Abstract
Background Chlamydia trachomatis is the etiological agent of trachoma the world's leading cause of infectious blindness. Here, we investigate whether protracted clearance of a primary infection in nonhuman primates is attributable to antigenic variation or related to the maturation of the anti-chlamydial humoral immune response specific to chlamydial antigens. Methodology/Principal Findings Genomic sequencing of organisms isolated throughout the protracted primary infection revealed that antigenic variation was not related to the inability of monkeys to efficiently resolve their infection. To explore the maturation of the humoral immune response as a possible reason for delayed clearance, sera were analyzed by radioimmunoprecipitation using intrinsically radio-labeled antigens prepared under non-denaturing conditions. Antibody recognition was restricted to the antigenically variable major outer membrane protein (MOMP) and a few antigenically conserved antigens. Recognition of MOMP occurred early post-infection and correlated with reduction in infectious ocular burdens but not with infection eradication. In contrast, antibody recognition of conserved antigens, identified as PmpD, Hsp60, CPAF and Pgp3, appeared late and correlated with infection eradication. Partial immunity to re-challenge was associated with a discernible antibody recall response against all antigens. Antibody recognition of PmpD and CPAF was destroyed by heat treatment while MOMP and Pgp3 were partially affected, indicating that antibody specific to conformational epitopes on these proteins may be important to protective immunity. Conclusions/Significance Our findings suggest that delayed clearance of chlamydial infection in NHP is not the result of antigenic variation but rather a consequence of the gradual maturation of the C. trachomatis antigen-specific humoral immune response. However, we cannot conclude that antibodies specific for these proteins play the primary role in host protective immunity as they could be surrogate markers of T cell immunity. Collectively, our results argue that an efficacious subunit trachoma vaccine might require a combination of these antigens delivered in their native conformation. Chlamydia trachomatis is the etiological agent of trachoma the world's leading cause of infectious blindness. In this study, we investigated whether delayed clearance of a primary infection in nonhuman primates was attributable to antigenic variation or related to gradual changes in the humoral immune response specific to chlamydial antigens. We found that antigenic variation was not related to the inability of monkeys to efficiently resolve their infection. However, exploring changes in the immune response as a possible reason for delayed clearance revealed that antibody recognition was restricted to the antigenically variable major surface protein and a few conserved polypeptides. Antibody recognition of the major antigenically variable surface protein correlated with the initial reduction in infectious burdens while recognition of conserved chlamydial antigens occurred late and correlated with infection eradication. These findings suggest that delayed clearance of chlamydial infection is not the result of antigenic variation but a consequence of a gradually evolving humoral immune response specific to different chlamydial antigens. Antibody recognition was at least partially directed against conformational epitopes, indicating that an efficacious subunit trachoma vaccine might require a combination of antigens delivered in their native conformation.
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21
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Galaleldeen A, Taylor AB, Chen D, Schuermann JP, Holloway SP, Hou S, Gong S, Zhong G, Hart PJ. Structure of the Chlamydia trachomatis immunodominant antigen Pgp3. J Biol Chem 2013; 288:22068-79. [PMID: 23703617 DOI: 10.1074/jbc.m113.475012] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Chlamydia trachomatis infection is the most common sexually transmitted bacterial disease. Left untreated, it can lead to ectopic pregnancy, pelvic inflammatory disease, and infertility. Here we present the structure of the secreted C. trachomatis protein Pgp3, an immunodominant antigen and putative virulence factor. The ∼84-kDa Pgp3 homotrimer, encoded on a cryptic plasmid, consists of globular N- and C-terminal assemblies connected by a triple-helical coiled-coil. The C-terminal domains possess folds similar to members of the TNF family of cytokines. The closest Pgp3 C-terminal domain structural homologs include a lectin from Burkholderia cenocepacia, the C1q component of complement, and a portion of the Bacillus anthracis spore surface protein BclA, all of which play roles in bioadhesion. The N-terminal domain consists of a concatenation of structural motifs typically found in trimeric viral proteins. The central parallel triple-helical coiled-coil contains an unusual alternating pattern of apolar and polar residue pairs that generate a rare right-handed superhelical twist. The unique architecture of Pgp3 provides the basis for understanding its role in chlamydial pathogenesis and serves as the platform for its optimization as a potential vaccine antigen candidate.
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Affiliation(s)
- Ahmad Galaleldeen
- Department of Biochemistry, University of Texas Health Science Center, San Antonio, Texas 78229, USA
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22
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Abstract
Trachoma, caused by Chlamydia trachomatis (Ct), is the leading infectious blinding disease worldwide. Chronic conjunctival inflammation develops in childhood and leads to eyelid scarring and blindness in adulthood. The immune response to Ct provides only partial protection against re-infection, which can be frequent. Moreover, the immune response is central to the development of scarring pathology, leading to loss of vision. Here we review the current literature on both protective and pathological immune responses in trachoma. The resolution of Ct infection in animal models is IFNγ-dependent, involving Th1 cells, but whether this is the case in human ocular infection still needs to be confirmed. An increasing number of studies indicate that innate immune responses arising from the epithelium and other innate immune cells, along with changes in matrix metalloproteinase activity, are important in the development of tissue damage and scarring. Current trachoma control measures, which are centred on repeated mass antibiotic treatment of populations, are logistically challenging and have the potential to drive antimicrobial resistance. A trachoma vaccine would offer significant advantages. However, limited understanding of the mechanisms of both protective immunity and immunopathology to Ct remain barriers to vaccine development.
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