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Lieberman NAP, Avendaño CC, Bakhash SAKM, Nunley E, Xie H, Giacani L, Berzkalns A, Soge OO, Reid TB, Golden MR, Greninger AL. Genomic Epidemiology of Treponema pallidum and Circulation of Strains With Diminished tprK Antigen Variation Capability in Seattle, 2021-2022. J Infect Dis 2024; 229:866-875. [PMID: 37769216 PMCID: PMC10938213 DOI: 10.1093/infdis/jiad368] [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: 05/09/2023] [Accepted: 08/24/2023] [Indexed: 09/30/2023] Open
Abstract
BACKGROUND The incidence of syphilis continues to increase in the United States, yet little is known about Treponema pallidum genomic epidemiology within American metropolitan areas. METHODS We performed whole-genome sequencing and tprK deep sequencing of 28 T. pallidum-containing specimens, collected mostly from remnant Aptima swab specimens from 24 individuals from Seattle Sexual Health Clinic during 2021-2022. RESULTS All 12 individuals infected with Nichols-lineage strains were men who have sex with men, while a specific SS14 cluster (mean, 0.33 single-nucleotide variant) included 1 man who has sex with women and 5 women. All T. pallidum strains sequenced were azithromycin resistant via 23S ribosomal RNA A2058G mutation. Identical T. pallidum genomic sequences were found in pharyngeal and rectal swab specimens taken concurrently from the same individuals. The tprK sequences were less variable between patient-matched specimens and between epidemiologically linked clusters. We detected a 528-base pair deletion in the tprK donor site locus, eliminating 9 donor sites, in T. pallidum genomes of 3 individuals with secondary syphilis, associated with diminution of TprK diversity. CONCLUSIONS We developed an end-to-end workflow for public health genomic surveillance of T. pallidum from remnant Aptima swab specimens. tprK sequencing may assist in linking cases beyond routine T. pallidum genome sequencing. T. pallidum strains with deletions in tprK donor sites currently circulate and are associated with diminished TprK antigenic diversity.
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Affiliation(s)
- Nicole A P Lieberman
- Department of Laboratory Medicine, University of Washington Medical Center, Seattle, Washington, USA
| | - Carlos C Avendaño
- Department of Laboratory Medicine, University of Washington Medical Center, Seattle, Washington, USA
| | - Shah A K Mohamed Bakhash
- Department of Laboratory Medicine, University of Washington Medical Center, Seattle, Washington, USA
| | - Ethan Nunley
- Department of Laboratory Medicine, University of Washington Medical Center, Seattle, Washington, USA
| | - Hong Xie
- Department of Laboratory Medicine, University of Washington Medical Center, Seattle, Washington, USA
| | - Lorenzo Giacani
- Department of Medicine, University of Washington Medical Center, Seattle, Washington, USA
- Department of Global Health, University of Washington, Seattle, Washington, USA
| | - Anna Berzkalns
- Public Health—Seattle & King County HIV/STD Program, Seattle, Washington, USA
| | - Olusegun O Soge
- Department of Laboratory Medicine, University of Washington Medical Center, Seattle, Washington, USA
- Department of Medicine, University of Washington Medical Center, Seattle, Washington, USA
- Department of Global Health, University of Washington, Seattle, Washington, USA
- Center for AIDS and STD, University of Washington, Seattle, Washington, USA
| | - Tara B Reid
- Department of Medicine, University of Washington Medical Center, Seattle, Washington, USA
| | - Matthew R Golden
- Department of Medicine, University of Washington Medical Center, Seattle, Washington, USA
- Public Health—Seattle & King County HIV/STD Program, Seattle, Washington, USA
- Department of Epidemiology, University of Washington, Seattle, Washington, USA
- Center for AIDS and STD, University of Washington, Seattle, Washington, USA
| | - Alexander L Greninger
- Department of Laboratory Medicine, University of Washington Medical Center, Seattle, Washington, USA
- Vaccine and Infectious Disease Division, Fred Hutchinson Cancer Research Center, Seattle, Washington, USA
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2
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Ciccarese G, Facciorusso A, Mastrolonardo M, Herzum A, Parodi A, Drago F. Atypical Manifestations of Syphilis: A 10-Year Retrospective Study. J Clin Med 2024; 13:1603. [PMID: 38541829 PMCID: PMC10971508 DOI: 10.3390/jcm13061603] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2024] [Revised: 02/24/2024] [Accepted: 02/28/2024] [Indexed: 07/24/2024] Open
Abstract
Background: The incidence of syphilis has increased in high-income countries in the past few decades, especially among men who have sex with men. In the present study, we aimed to analyze the correlations between atypical syphilis manifestations and the demographic, clinical, and laboratory features of patients and to review unusual presentations of syphilis reported in the literature. Methods: We conducted a retrospective analysis of 307 patients with syphilis diagnosed between 1 January 2013 and 31 October 2023 at the sexually transmitted infection (STI) centers of the University of Genoa and University of Foggia with both typical and atypical manifestations of disease. Results: In our series, atypical manifestations were detected in 25.8% of the patients, especially in the secondary stage of the disease. Lesions with annular morphology and lesions presenting as itchy erythematous scaly plaques with a psoriasiform appearance were the most common atypical presentations of secondary syphilis. A statistical analysis revealed that homosexual orientation, syphilis reinfection, and venereal disease research laboratory (VDRL) titers > 1:32 were correlated with atypical manifestations. Conclusions: Our study demonstrates that the spectrum of syphilis manifestations, in all the stages of the disease, is wide; atypical manifestations often pose diagnostic challenges, may delay the provision of appropriate treatment, and facilitate the spread of the infection.
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Affiliation(s)
- Giulia Ciccarese
- Section of Dermatology, Department of Medical and Surgical Sciences, University of Foggia, Viale Pinto 1, 71122 Foggia, Italy; (G.C.); (M.M.)
| | - Antonio Facciorusso
- Gastroenterology Unit, Department of Medical and Surgical Sciences, University of Foggia, 00161 Foggia, Italy;
| | - Mario Mastrolonardo
- Section of Dermatology, Department of Medical and Surgical Sciences, University of Foggia, Viale Pinto 1, 71122 Foggia, Italy; (G.C.); (M.M.)
| | - Astrid Herzum
- Dermatology Unit, IRCCS Giannina Gaslini, 16147 Genova, Italy
| | - Aurora Parodi
- Section of Dermatology, Department of Health Sciences, University of Genoa, IRCCS—Ospedale Policlinico San Martino, 16132 Genoa, Italy; (A.P.); (F.D.)
| | - Francesco Drago
- Section of Dermatology, Department of Health Sciences, University of Genoa, IRCCS—Ospedale Policlinico San Martino, 16132 Genoa, Italy; (A.P.); (F.D.)
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3
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Majander K, Pla-Díaz M, du Plessis L, Arora N, Filippini J, Pezo-Lanfranco L, Eggers S, González-Candelas F, Schuenemann VJ. Redefining the treponemal history through pre-Columbian genomes from Brazil. Nature 2024; 627:182-188. [PMID: 38267579 PMCID: PMC10917687 DOI: 10.1038/s41586-023-06965-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2023] [Accepted: 12/12/2023] [Indexed: 01/26/2024]
Abstract
The origins of treponemal diseases have long remained unknown, especially considering the sudden onset of the first syphilis epidemic in the late 15th century in Europe and its hypothesized arrival from the Americas with Columbus' expeditions1,2. Recently, ancient DNA evidence has revealed various treponemal infections circulating in early modern Europe and colonial-era Mexico3-6. However, there has been to our knowledge no genomic evidence of treponematosis recovered from either the Americas or the Old World that can be reliably dated to the time before the first trans-Atlantic contacts. Here, we present treponemal genomes from nearly 2,000-year-old human remains from Brazil. We reconstruct four ancient genomes of a prehistoric treponemal pathogen, most closely related to the bejel-causing agent Treponema pallidum endemicum. Contradicting the modern day geographical niche of bejel in the arid regions of the world, the results call into question the previous palaeopathological characterization of treponeme subspecies and showcase their adaptive potential. A high-coverage genome is used to improve molecular clock date estimations, placing the divergence of modern T. pallidum subspecies firmly in pre-Columbian times. Overall, our study demonstrates the opportunities within archaeogenetics to uncover key events in pathogen evolution and emergence, paving the way to new hypotheses on the origin and spread of treponematoses.
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Affiliation(s)
- Kerttu Majander
- Institute of Evolutionary Medicine, University of Zurich, Zurich, Switzerland.
- Department of Evolutionary Anthropology, University of Vienna, Vienna, Austria.
- Department of Environmental Sciences, University of Basel, Basel, Switzerland.
| | - Marta Pla-Díaz
- Unidad Mixta Infección y Salud Pública, FISABIO/Universidad de Valencia-I2SysBio, Valencia, Spain
- CIBER in Epidemiology and Public Health, Instituto de Salud Carlos III, Madrid, Spain
| | - Louis du Plessis
- Department of Biosystems Science and Engineering, ETH Zürich, Basel, Switzerland
- Swiss Institute of Bioinformatics, Quartier Sorge, Lausanne, Switzerland
| | - Natasha Arora
- Zurich Institute of Forensic Medicine, University of Zurich, Zurich, Switzerland
| | - Jose Filippini
- Department of Genetic and Evolutionary Biology, University of São Paulo, São Paulo, Brazil
| | - Luis Pezo-Lanfranco
- Department of Genetic and Evolutionary Biology, University of São Paulo, São Paulo, Brazil
- Institute of Environmental Science and Technology (ICTA) and Prehistory Department, Universitat Autònoma de Barcelona, Bellaterra, Spain
| | - Sabine Eggers
- Department of Genetic and Evolutionary Biology, University of São Paulo, São Paulo, Brazil
- Department of Anthropology, Natural History Museum Vienna, Vienna, Austria
| | - Fernando González-Candelas
- Unidad Mixta Infección y Salud Pública, FISABIO/Universidad de Valencia-I2SysBio, Valencia, Spain.
- CIBER in Epidemiology and Public Health, Instituto de Salud Carlos III, Madrid, Spain.
| | - Verena J Schuenemann
- Institute of Evolutionary Medicine, University of Zurich, Zurich, Switzerland.
- Department of Evolutionary Anthropology, University of Vienna, Vienna, Austria.
- Department of Environmental Sciences, University of Basel, Basel, Switzerland.
- Human Evolution and Archaeological Sciences (HEAS), University of Vienna, Vienna, Austria.
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Liu D, Chen R, He Y, Wang YJ, Lin LR, Liu LL, Yang TC, Tong ML. Longitudinal Variations in the tprK Gene of Treponema pallidum in an Amoy Strain-Infected Rabbit Model. Microbiol Spectr 2023; 11:e0106723. [PMID: 37347187 PMCID: PMC10433980 DOI: 10.1128/spectrum.01067-23] [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: 03/12/2023] [Accepted: 06/01/2023] [Indexed: 06/23/2023] Open
Abstract
Heterogeneous tprK sequences have been hypothesized to be an important factor for persistent infection of Treponema pallidum subsp. pallidum (T. pallidum) in humans. Previous research has only explored tprK diversity using a rabbit model infected with almost clonal isolates, which is inconsistent with the fact that infected human isolates contain multiple heterogeneous tprK sequences. Here, we used the T. pallidum Amoy strain with heterogeneous tprK sequences to establish a rabbit infection model and explore longitudinal variations in the tprK gene under normal infection, immunosuppression treatment, and benzathine penicillin G (BPG) treatment using next-generation sequencing. The diversity of the tprK gene was high in all three groups but was highest in the control group and lowest in the BPG group. Interestingly, the overall diversity of tprK in all three groups decreased during infection, exhibiting a "more to less" trend, indicating that survival selection may be an important factor affecting tprK variation in the later infection stage. BPG treatment appeared to reduce the diversity of tprK but increased the frequency of predominant sequence changes, which might facilitate the escape of T. pallidum from the host immune clearance. Furthermore, the original predominant V region sequence did not disappear with disease progression but retained a relatively high proportion within the population, suggesting a new direction for tprK-related vaccine research. This study provides insights into longitudinal variations within the highly heterogeneous tprK gene sequences of T. pallidum and will contribute to further exploration of the pathogenesis of syphilis. IMPORTANCE The tprK variations are an important factor in persistent T. pallidum infection. A nearly clonal isolate has been used previously to investigate the mechanism of tprK gene variations; however, clinical T. pallidum isolates in infected humans exhibit multiple heterogeneous tprK sequences. Here, we use next-generation sequencing to explore longitudinal variations in the tprK gene under normal infection and immunosuppression and benzathine penicillin G treatment in a rabbit model infected with the Amoy strain with heterogeneous tprK sequences. The overall diversity of tprK in all three groups was high and decreased during infection, exhibiting a "more to less" trend. Benzathine penicillin G treatment reduced the diversity of tprK but increased the frequency of predominant sequence changes. Moreover, the original predominant V region sequence did not disappear as the disease progressed but remained at a relatively high proportion within the population. The research results give us a new understanding about tprK variation.
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Affiliation(s)
- Dan Liu
- Center of Clinical Laboratory, Zhongshan Hospital, School of Medicine, Xiamen University, Xiamen, China
- Institute of Infectious Disease, School of Medicine, Xiamen University, Xiamen, China
| | - Rui Chen
- Institute of Infectious Disease, School of Medicine, Xiamen University, Xiamen, China
| | - Yun He
- Institute of Infectious Disease, School of Medicine, Xiamen University, Xiamen, China
| | - Yong-jing Wang
- Institute of Infectious Disease, School of Medicine, Xiamen University, Xiamen, China
| | - Li-Rong Lin
- Center of Clinical Laboratory, Zhongshan Hospital, School of Medicine, Xiamen University, Xiamen, China
- Institute of Infectious Disease, School of Medicine, Xiamen University, Xiamen, China
| | - Li-Li Liu
- Center of Clinical Laboratory, Zhongshan Hospital, School of Medicine, Xiamen University, Xiamen, China
- Institute of Infectious Disease, School of Medicine, Xiamen University, Xiamen, China
| | - Tian-Ci Yang
- Center of Clinical Laboratory, Zhongshan Hospital, School of Medicine, Xiamen University, Xiamen, China
- Institute of Infectious Disease, School of Medicine, Xiamen University, Xiamen, China
| | - Man-Li Tong
- Center of Clinical Laboratory, Zhongshan Hospital, School of Medicine, Xiamen University, Xiamen, China
- Institute of Infectious Disease, School of Medicine, Xiamen University, Xiamen, China
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5
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Liu D, Liu LL, Zheng XQ, Chen R, Lin LR, Yang TC, Tong ML. Genetic Profiling of the Full-Length tprK Gene in Patients with Primary and Secondary Syphilis. Microbiol Spectr 2023; 11:e0493122. [PMID: 37036342 PMCID: PMC10269439 DOI: 10.1128/spectrum.04931-22] [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: 11/30/2022] [Accepted: 03/17/2023] [Indexed: 04/11/2023] Open
Abstract
TprK antigenic variation is acknowledged as an important strategy developed by Treponema pallidum to achieve immune evasion. Previous studies applied short-read sequencing to explore tprK gene sequence diversity in clinical samples; however, due to the limitations of short-read sequencing, it was difficult to determine the linkage between the seven V regions, and crucial information about full-length tprK variants was lost. Although two recent studies explored complete tprK gene profiles in natural human syphilis infection, there are still too few profiled full-length tprK variants among clinical T. pallidum isolates to fully understand the characteristics of TprK coding diversity. Here, Pacific Biosciences (PacBio) long-read sequencing was applied to examine the diversity of full-length tprK variants in 21 clinical T. pallidum isolates from 11 patients with primary syphilis and 10 patients with secondary syphilis. A total of 398 high-confidence full-length sequences, which presented remarkable sequence heterogeneity, were found. However, these full-length tprK variants exhibited limited variation in length and GC content, showing 24 length types and average GC content of 51.5 ± 0.42% and 51.6 ± 0.26% for primary and secondary syphilis samples, respectively. Additionally, the combined patterns of mutated V regions generating new tprK variants were obviously different in primary and secondary syphilis samples. The diversity of tprK gene sequences in primary syphilis samples may represent the underlying variability of the bacterium; conversely, the variability of the tprK gene in secondary syphilis samples may more accurately reflect how T. pallidum escapes host immune clearance. These data highlight the tprK gene as an important coding gene that shows conflicting genetic characteristics but underlies the persistence of spirochete infection. IMPORTANCE The resurgence of syphilis in both low- and high-income countries has attracted attention, and persistent infection by the pathogen has long been a research focus. The tprK gene, encoding the hypervariable outer membrane protein, is thought to be responsible for pathogen immune evasion and persistent infection. Here, PacBio long-read sequencing was applied to examine the diversity of full-length tprK variants in 21 clinical T. pallidum isolates from 11 patients with primary syphilis and 10 patients with secondary syphilis. The results showed that the sequences of the tprK gene were remarkably heterogeneous; however, the sequences presented limited variation in length and GC content. The investigation of the combined patterns of the V regions allowed us to gain insight into the features of the tprK gene generating new variants at different clinical stages. The findings of this study will be helpful for further exploration of the pathogenesis of syphilis.
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Affiliation(s)
- Dan Liu
- Center of Clinical Laboratory, Zhongshan Hospital, School of Medicine, Xiamen University, Xiamen, China
- Institute of Infectious Disease, School of Medicine, Xiamen University, Xiamen, China
| | - Li-Li Liu
- Center of Clinical Laboratory, Zhongshan Hospital, School of Medicine, Xiamen University, Xiamen, China
- Institute of Infectious Disease, School of Medicine, Xiamen University, Xiamen, China
| | - Xin-Qi Zheng
- Institute of Infectious Disease, School of Medicine, Xiamen University, Xiamen, China
| | - Rui Chen
- Institute of Infectious Disease, School of Medicine, Xiamen University, Xiamen, China
| | - Li-Rong Lin
- Center of Clinical Laboratory, Zhongshan Hospital, School of Medicine, Xiamen University, Xiamen, China
- Institute of Infectious Disease, School of Medicine, Xiamen University, Xiamen, China
| | - Tian-Ci Yang
- Center of Clinical Laboratory, Zhongshan Hospital, School of Medicine, Xiamen University, Xiamen, China
- Institute of Infectious Disease, School of Medicine, Xiamen University, Xiamen, China
| | - Man-Li Tong
- Center of Clinical Laboratory, Zhongshan Hospital, School of Medicine, Xiamen University, Xiamen, China
- Institute of Infectious Disease, School of Medicine, Xiamen University, Xiamen, China
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Ávila-Nieto C, Pedreño-López N, Mitjà O, Clotet B, Blanco J, Carrillo J. Syphilis vaccine: challenges, controversies and opportunities. Front Immunol 2023; 14:1126170. [PMID: 37090699 PMCID: PMC10118025 DOI: 10.3389/fimmu.2023.1126170] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2022] [Accepted: 03/27/2023] [Indexed: 04/25/2023] Open
Abstract
Syphilis is a sexually or vertically (mother to fetus) transmitted disease caused by the infection of Treponema pallidum subspecie pallidum (TPA). The incidence of syphilis has increased over the past years despite the fact that this bacterium is an obligate human pathogen, the infection route is well known, and the disease can be successfully treated with penicillin. As complementary measures to preventive campaigns and early treatment of infected individuals, development of a syphilis vaccine may be crucial for controlling disease spread and/or severity, particularly in countries where the effectiveness of the aforementioned measures is limited. In the last century, several vaccine prototypes have been tested in preclinical studies, mainly in rabbits. While none of them provided protection against infection, some prototypes prevented bacteria from disseminating to distal organs, attenuated lesion development, and accelerated their healing. In spite of these promising results, there is still some controversy regarding the identification of vaccine candidates and the characteristics of a syphilis-protective immune response. In this review, we describe what is known about TPA immune response, and the main mechanisms used by this pathogen to evade it. Moreover, we emphasize the importance of integrating this knowledge, in conjunction with the characterization of outer membrane proteins (OMPs), to expedite the development of a syphilis vaccine that can protect against TPA infection.
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Affiliation(s)
- Carlos Ávila-Nieto
- IrsiCaixa AIDS Research Institute, Badalona, Spain
- Autonomous University of Barcelona, Cerdanyola del Vallès, Catalonia, Spain
| | | | - Oriol Mitjà
- Skin Neglected Tropical Diseases and Sexually Transmitted Infections Department, Germans Trias i Pujol Hospital, Badalona, Spain
- Fight Infections Foundation, Germans Trias i Pujol Hospital, Badalona, Catalonia, Spain
- Centre for Health and Social Care Research (CESS), Faculty of Medicine, University of Vic – Central University of Catalonia (UVic – UCC), Vic, Catalonia, Spain
| | - Bonaventura Clotet
- IrsiCaixa AIDS Research Institute, Badalona, Spain
- Fight Infections Foundation, Germans Trias i Pujol Hospital, Badalona, Catalonia, Spain
- Centre for Health and Social Care Research (CESS), Faculty of Medicine, University of Vic – Central University of Catalonia (UVic – UCC), Vic, Catalonia, Spain
- Germans Trias i Pujol Research Institute (IGTP), Badalona, Spain
- CIBERINFEC, Instituto de Salut Carlos III (ISCIII), Madrid, Spain
| | - Julià Blanco
- IrsiCaixa AIDS Research Institute, Badalona, Spain
- Centre for Health and Social Care Research (CESS), Faculty of Medicine, University of Vic – Central University of Catalonia (UVic – UCC), Vic, Catalonia, Spain
- Germans Trias i Pujol Research Institute (IGTP), Badalona, Spain
- CIBERINFEC, Instituto de Salut Carlos III (ISCIII), Madrid, Spain
| | - Jorge Carrillo
- IrsiCaixa AIDS Research Institute, Badalona, Spain
- Germans Trias i Pujol Research Institute (IGTP), Badalona, Spain
- CIBERINFEC, Instituto de Salut Carlos III (ISCIII), Madrid, Spain
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Romeis E, Lieberman NAP, Molini B, Tantalo LC, Chung B, Phung Q, Avendaño C, Vorobieva A, Greninger AL, Giacani L. Treponema pallidum subsp. pallidum with an Artificially impaired TprK antigenic variation system is attenuated in the Rabbit model of syphilis. PLoS Pathog 2023; 19:e1011259. [PMID: 36940224 PMCID: PMC10063172 DOI: 10.1371/journal.ppat.1011259] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2022] [Revised: 03/30/2023] [Accepted: 03/01/2023] [Indexed: 03/21/2023] Open
Abstract
BACKGROUND The TprK protein of the syphilis agent, Treponema pallidum subsp. pallidum (T. pallidum), undergoes antigenic variation in seven discrete variable (V) regions via non-reciprocal segmental gene conversion. These recombination events transfer information from a repertoire of 53 silent chromosomal donor cassettes (DCs) into the single tprK expression site to continually generate TprK variants. Several lines of research developed over the last two decades support the theory that this mechanism is central to T. pallidum's ability for immune avoidance and persistence in the host. Structural and modeling data, for example, identify TprK as an integral outer membrane porin with the V regions exposed on the pathogen's surface. Furthermore, infection-induced antibodies preferentially target the V regions rather than the predicted β-barrel scaffolding, and sequence variation abrogates the binding of antibodies elicited by antigenically different V regions. Here, we engineered a T. pallidum strain to impair its ability to vary TprK and assessed its virulence in the rabbit model of syphilis. PRINCIPAL FINDINGS A suicide vector was transformed into the wild-type (WT) SS14 T. pallidum isolate to eliminate 96% of its tprK DCs. The resulting SS14-DCKO strain exhibited an in vitro growth rate identical to the untransformed strain, supporting that the elimination of the DCs did not affect strain viability in absence of immune pressure. In rabbits injected intradermally with the SS14-DCKO strain, generation of new TprK sequences was impaired, and the animals developed attenuated lesions with a significantly reduced treponemal burden compared to control animals. During infection, clearance of V region variants originally in the inoculum mirrored the generation of antibodies to these variants, although no new variants were generated in the SS14-DCKO strain to overcome immune pressure. Naïve rabbits that received lymph node extracts from animals infected with the SS14-DCKO strain remained uninfected. CONCLUSION These data further support the critical role of TprK in T. pallidum virulence and persistence during infection.
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Affiliation(s)
- Emily Romeis
- Department of Medicine, Division of Allergy and Infectious Diseases, University of Washington, Seattle, Washington, United States of America
| | - Nicole A. P. Lieberman
- Department of Laboratory Medicine and Pathology, University of Washington, Seattle, Washington, United States of America
| | - Barbara Molini
- Department of Medicine, Division of Allergy and Infectious Diseases, University of Washington, Seattle, Washington, United States of America
| | - Lauren C. Tantalo
- Department of Medicine, Division of Allergy and Infectious Diseases, University of Washington, Seattle, Washington, United States of America
| | - Benjamin Chung
- Department of Laboratory Medicine and Pathology, University of Washington, Seattle, Washington, United States of America
| | - Quynh Phung
- Department of Laboratory Medicine and Pathology, University of Washington, Seattle, Washington, United States of America
| | - Carlos Avendaño
- Department of Laboratory Medicine and Pathology, University of Washington, Seattle, Washington, United States of America
| | - Anastassia Vorobieva
- VIB-VUB Center for Structural Biology, VIB, Brussels, Belgium
- Structural Biology Brussels, Vrije Universiteit Brussel, Brussels, Belgium
| | - Alexander L. Greninger
- Department of Laboratory Medicine and Pathology, University of Washington, Seattle, Washington, United States of America
- Vaccine and Infectious Disease Division, Fred Hutchinson Cancer Research Center, Seattle, Washington, United States of America
| | - Lorenzo Giacani
- Department of Medicine, Division of Allergy and Infectious Diseases, University of Washington, Seattle, Washington, United States of America
- Department of Global Health, University of Washington, Seattle, Washington, United States of America
- * E-mail:
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8
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Edmondson DG, De Lay BD, Hanson BM, Kowis LE, Norris SJ. Clonal isolates of Treponema pallidum subsp. pallidum Nichols provide evidence for the occurrence of microevolution during experimental rabbit infection and in vitro culture. PLoS One 2023; 18:e0281187. [PMID: 36917571 PMCID: PMC10013896 DOI: 10.1371/journal.pone.0281187] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2022] [Accepted: 01/17/2023] [Indexed: 03/15/2023] Open
Abstract
The recent development of a system for long-term in vitro culture of the syphilis spirochete, Treponema pallidum subsp. pallidum, has introduced the possibility of detailed genetic analysis of this bacterium. In this study, the in vitro culture system was used to isolate and characterize clonal populations of T. pallidum subsp. pallidum Nichols, the most widely studied strain. In limiting dilutions experiments, it was possible to establish cultures with inocula as low as 0.5 T. pallidum per well despite the long generation time (~35 to 40 hours) of this organism. Six Nichols strain clones isolated by limiting dilution were characterized in detail. All clones exhibited indistinguishable morphology and motility, highly similar in vitro multiplication rates, and comparable infectivity in the rabbit model (ID50 ≤ 100 bacteria). Genomic sequencing revealed sequence heterogeneity in the form of insertions or deletions at 5 sites, single nucleotide variations at 20 sites, and polynucleotide (polyG/C) tract length differences at 22 locations. Genomic sequences of the uncloned Nichols strain preparations propagated in rabbits or in vitro cultures exhibited substantial heterogeneity at these locations, indicating coexistence of many varied 'clonotypes' within these populations. Nearly all genetic variations were specific for the Nichols strain and were not detected in the >280 T. pallidum genomic sequences that are currently available. We hypothesize that these Nichols strain-specific sequence variations arose independently either during human infection or within the 110 years since the strain's initial isolation, and thus represent examples of microevolution and divergence.
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Affiliation(s)
- Diane G. Edmondson
- Department of Pathology & Laboratory Medicine, McGovern Medical School, University of Texas Health Science Center, Houston, Texas, United States of America
| | - Bridget D. De Lay
- Department of Pathology & Laboratory Medicine, McGovern Medical School, University of Texas Health Science Center, Houston, Texas, United States of America
| | - Blake M. Hanson
- Department of Pediatrics, McGovern Medical School, University of Texas Health Science Center, Houston, Texas, United States of America
- Department of Epidemiology, Human Genetics & Environmental Sciences, Center for Infectious Diseases, School of Public Health, University of Texas Health Science Center, Houston, Texas, United States of America
| | - Lindsay E. Kowis
- Houston Methodist Research Institute, Infectious Disease, Houston, Texas, United States of America
| | - Steven J. Norris
- Department of Pathology & Laboratory Medicine, McGovern Medical School, University of Texas Health Science Center, Houston, Texas, United States of America
- Department of Microbiology & Molecular Genetics, McGovern Medical School, University of Texas Health Science Center, Houston, Texas, United States of America
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Romeis E, Lieberman NAP, Molini B, Tantalo LC, Chung B, Phung Q, Avendaño C, Vorobieva A, Greninger AL, Giacani L. Treponema pallidum subsp. pallidum with an Artificially Impaired TprK Antigenic Variation System is Attenuated in the Rabbit Model of Syphilis. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.01.18.524629. [PMID: 36711914 PMCID: PMC9882362 DOI: 10.1101/2023.01.18.524629] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Background The TprK protein of the syphilis agent, Treponema pallidum subsp. pallidum ( T. pallidum ), undergoes antigenic variation in seven discrete variable (V) regions via non-reciprocal segmental gene conversion. These recombination events transfer information from a repertoire of 53 silent chromosomal donor cassettes (DCs) into the single tprK expression site to continually generate TprK variants. Several lines of research developed over the last two decades support the theory that this mechanism is central to T. pallidum 's ability for immune avoidance and persistence in the host. Structural and modeling data, for example, identify TprK as an integral outer membrane porin with the V regions exposed on the pathogen's surface. Furthermore, infection-induced antibodies preferentially target the V regions rather than the predicted β-barrel scaffolding, and sequence variation abrogates the binding of antibodies elicited by antigenically different V regions. Here, we engineered a T. pallidum strain to impair its ability to vary TprK and assessed its virulence in the rabbit model of syphilis. Principal findings A suicide vector was transformed into the wild-type (WT) SS14 T. pallidum isolate to eliminate 96% of its tprK DCs. The resulting SS14-DC KO strain exhibited an in vitro growth rate identical to the untransformed strain, supporting that the elimination of the DCs did not affect strain viability in absence of immune pressure. In rabbits injected intradermally with the SS14-DC KO strain, generation of new TprK sequences was impaired, and the animals developed attenuated lesions with a significantly reduced treponemal burden compared to control animals. During infection, clearance of V region variants originally in the inoculum mirrored the generation of antibodies to these variants, although no new variants were generated in the SS14-DC KO strain to overcome immune pressure. Naïve rabbits that received lymph node extracts from animals infected with the SS14-DC KO strain remained uninfected. Conclusion These data further support the critical role of TprK in T. pallidum virulence and persistence during infection. Author Summary Syphilis is still endemic in low- and middle-income countries, and it has been resurgent in high-income nations, including the U.S., for years. In endemic areas, there is still significant morbidity and mortality associated with this disease, particularly when its causative agent, the spirochete Treponema pallidum subsp . pallidum ( T. pallidum ) infects the fetus during pregnancy. Improving our understanding of syphilis pathogenesis and T. pallidum biology could help investigators devise better control strategies for this serious infection. Now that tools to genetically manipulate this pathogen are available, we can engineer T. pallidum strains lacking specific genes or genomic regions known (or believed) to be associated with virulence. This approach can shed light on the role of the ablated genes or sequences in disease development using loss-of-function strains. Here, we derived a knockout (KO) T. pallidum mutant (SS14-DC KO ) impaired in its ability to undergo antigenic variation of TprK, a protein that has long been hypothesized to be central in evasion of the host immune response and pathogen persistence during infection. When compared to the WT isolate, which is still capable of antigenic variation, the SS14-DC KO strain is significantly attenuated in its ability to proliferate and to induce early disease manifestations in infected rabbits. Our results further support the importance of TprK antigenic variation in syphilis pathogenesis and pathogen persistence.
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Tang Y, Zhou Y, He B, Cao T, Zhou X, Ning L, Chen E, Li Y, Xie X, Peng B, Hu Y, Liu S. Investigation of the immune escape mechanism of Treponema pallidum. Infection 2022; 51:305-321. [PMID: 36260281 DOI: 10.1007/s15010-022-01939-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2022] [Accepted: 10/07/2022] [Indexed: 11/25/2022]
Abstract
BACKGROUND Syphilis is a chronic sexually transmitted disease caused by Treponema pallidum subspecies pallidum (T. pallidum), which is a public health problem that seriously affects human health worldwide. T. pallidum is characterized by early transmission and immune escape and is therefore termed an "invisible pathogen". METHODS This review systematically summarizes the host's innate and adaptive immune responses to T. pallidum infection as well as the escape mechanisms of T. pallidum. PURPOSE To lay the foundation for assessing the pathogenic mechanism and the systematic prevention and treatment of syphilis. CONCLUSION The immune escape mechanism of T. pallidum plays an important role in its survival. Exploring the occurrence and development of these mechanisms has laid the foundation for the development of syphilis vaccine.
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Affiliation(s)
- Yun Tang
- Department of Clinical Laboratory Medicine, Institution of Microbiology and Infectious Diseases, Hengyang Medical School, The First Affiliated Hospital, University of South China, No. 69, Chuanshan Road, Hengyang City, 421000, Hunan, China
| | - Yingjie Zhou
- Department of Clinical Laboratory Medicine, Institution of Microbiology and Infectious Diseases, Hengyang Medical School, The First Affiliated Hospital, University of South China, No. 69, Chuanshan Road, Hengyang City, 421000, Hunan, China
| | - Bisha He
- Department of Clinical Laboratory Medicine, Institution of Microbiology and Infectious Diseases, Hengyang Medical School, The First Affiliated Hospital, University of South China, No. 69, Chuanshan Road, Hengyang City, 421000, Hunan, China
| | - Ting Cao
- Department of Clinical Laboratory Medicine, Institution of Microbiology and Infectious Diseases, Hengyang Medical School, The First Affiliated Hospital, University of South China, No. 69, Chuanshan Road, Hengyang City, 421000, Hunan, China
| | - Xiangping Zhou
- Department of Clinical Laboratory Medicine, Institution of Microbiology and Infectious Diseases, Hengyang Medical School, The First Affiliated Hospital, University of South China, No. 69, Chuanshan Road, Hengyang City, 421000, Hunan, China
| | - Lichang Ning
- Department of Clinical Laboratory Medicine, Institution of Microbiology and Infectious Diseases, Hengyang Medical School, The First Affiliated Hospital, University of South China, No. 69, Chuanshan Road, Hengyang City, 421000, Hunan, China
| | - En Chen
- Department of Clinical Laboratory Medicine, Institution of Microbiology and Infectious Diseases, Hengyang Medical School, The First Affiliated Hospital, University of South China, No. 69, Chuanshan Road, Hengyang City, 421000, Hunan, China
| | - Yumeng Li
- Department of Clinical Laboratory Medicine, Institution of Microbiology and Infectious Diseases, Hengyang Medical School, The First Affiliated Hospital, University of South China, No. 69, Chuanshan Road, Hengyang City, 421000, Hunan, China
| | - Xiaoping Xie
- Department of Clinical Laboratory Medicine, Institution of Microbiology and Infectious Diseases, Hengyang Medical School, The First Affiliated Hospital, University of South China, No. 69, Chuanshan Road, Hengyang City, 421000, Hunan, China
| | - Binfeng Peng
- Department of Clinical Laboratory Medicine, Institution of Microbiology and Infectious Diseases, Hengyang Medical School, The First Affiliated Hospital, University of South China, No. 69, Chuanshan Road, Hengyang City, 421000, Hunan, China
| | - Yibao Hu
- Department of Clinical Laboratory Medicine, Institution of Microbiology and Infectious Diseases, Hengyang Medical School, The First Affiliated Hospital, University of South China, No. 69, Chuanshan Road, Hengyang City, 421000, Hunan, China
| | - Shuangquan Liu
- Department of Clinical Laboratory Medicine, Institution of Microbiology and Infectious Diseases, Hengyang Medical School, The First Affiliated Hospital, University of South China, No. 69, Chuanshan Road, Hengyang City, 421000, Hunan, China.
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11
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Kojima N, Konda KA, Klausner JD. Notes on syphilis vaccine development. Front Immunol 2022; 13:952284. [PMID: 35967432 PMCID: PMC9365935 DOI: 10.3389/fimmu.2022.952284] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2022] [Accepted: 06/30/2022] [Indexed: 11/13/2022] Open
Abstract
The quest for a syphilis vaccine to provide protection from infection or disease began not long after the isolation of the first Treponema pallidum subspecies pallidum (T. pallidum) strain in 1912. Yet, a practical and effective vaccine formulation continues to elude scientists. Over the last few years, however, efforts toward developing a syphilis vaccine have increased thanks to an improved understanding of the repertoire of T. pallidum outer membrane proteins (OMPs), which are the most likely syphilis vaccine candidates. More has been also learned about the molecular mechanisms behind pathogen persistence and immune evasion. Published vaccine formulations based on a subset of the pathogen's OMPs have conferred only partial protection upon challenge of immunized laboratory animals, primarily rabbits. Nonetheless, those experiments have improved our approach to the choice of immunization regimens, adjuvants, and vaccine target selection, although significant knowledge gaps remain. Herein, we provide a brief overview on current technologies and approaches employed in syphilis vaccinology, and possible future directions to develop a vaccine that could be pivotal to future syphilis control and elimination initiatives.
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Affiliation(s)
- Noah Kojima
- Department of Medicine, University of California Los Angeles, Los Angeles, CA, United States
| | - Kelika A. Konda
- Department of Medicine, University of California Los Angeles, Los Angeles, CA, United States
- Centro de Investigación Interdisciplinaria en Sexualidad Sida y Sociedad, Universidad Peruana Cayetano Heredia, Lima, Peru
| | - Jeffrey D. Klausner
- Departments of Medicine and Population and Public Health Sciences, Keck School of Medicine of the University of Southern California, Los Angeles, CA, United States
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12
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Lian T, Zhang B, Giacani L, Kou C, Yang X, Zhang R, Wang Q. Full-length TprK of Treponema pallidum subsp. pallidum in lipid nanodiscs is a monomeric porin. Enzyme Microb Technol 2022; 153:109897. [PMID: 34670182 PMCID: PMC10929906 DOI: 10.1016/j.enzmictec.2021.109897] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2021] [Revised: 07/27/2021] [Accepted: 08/23/2021] [Indexed: 11/22/2022]
Abstract
TprK is a key virulence factor of Treponema pallidum subsp. pallidum (T. pallidum) due to its ability to undergo intra-strain antigenic variation through gene conversion. This mechanism can generate millions of tprK gene and protein variants to allow immune evasion and pathogen persistence during infection. In silico structural modeling supports that TprK is an outer membrane β-barrel with porin function and with several surface-exposed loops, seven of which corresponding to the variable regions. No definitive structural of functional data, however, exist for this protein aside from its role in immune evasion. Studies to elucidate TprK biological function as a porin, are hindered by the evidence that TprK is not abundant on T. pallidum outer membrane, and by the fragility of T. pallidum envelope. To gain insight onto TprK structure and possible function as a porin, we used an Escherichia coli - based expression system that yielded highly pure full-length TprK without any intermediate denaturation step, and proceeded to reconstitute it in detergents and lipid nanodiscs. Visualization of TprK in nanodiscs using negative staining electron microscopy supported that TprK is a monomeric porin in an artificial lipid environment mimicking T. pallidum membrane. Our work provided evidence that TprK is a possible porin transporter of T. pallidum, a biological function compatible with its structural models. These results bring us closer to a comprehensive understanding of the function of this important virulence factor in syphilis pathogenesis and T. pallidum biology.
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Affiliation(s)
- Tingting Lian
- Institute of Dermatology, Chinese Academy of Medical Sciences and Peking Union Medical College, Nanjing 210042, China.
| | - Bing Zhang
- Shanghai Institute for Advanced Immunochemical Studies and School of Life Science and Technology, ShanghaiTech University, Shanghai 200120, China.
| | - Lorenzo Giacani
- Department of Medicine, Division of Allergy and Infectious Diseases, University of Washington, Seattle, WA, USA; Department of Global Health, University of Washington, Seattle, WA, USA.
| | - Caixia Kou
- Institute of Dermatology, Chinese Academy of Medical Sciences and Peking Union Medical College, Nanjing 210042, China.
| | - Xiuna Yang
- Shanghai Institute for Advanced Immunochemical Studies and School of Life Science and Technology, ShanghaiTech University, Shanghai 200120, China.
| | - Ruili Zhang
- Department of Dermatology, The Second Affiliated Hospital of Nanjing Medical University, Nanjing 210042, China.
| | - Qianqiu Wang
- Institute of Dermatology, Chinese Academy of Medical Sciences and Peking Union Medical College, Nanjing 210042, China.
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13
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Lieberman NAP, Lin MJ, Xie H, Shrestha L, Nguyen T, Huang ML, Haynes AM, Romeis E, Wang QQ, Zhang RL, Kou CX, Ciccarese G, Dal Conte I, Cusini M, Drago F, Nakayama SI, Lee K, Ohnishi M, Konda KA, Vargas SK, Eguiluz M, Caceres CF, Klausner JD, Mitjà O, Rompalo A, Mulcahy F, Hook EW, Lukehart SA, Casto AM, Roychoudhury P, DiMaio F, Giacani L, Greninger AL. Treponema pallidum genome sequencing from six continents reveals variability in vaccine candidate genes and dominance of Nichols clade strains in Madagascar. PLoS Negl Trop Dis 2021; 15:e0010063. [PMID: 34936652 PMCID: PMC8735616 DOI: 10.1371/journal.pntd.0010063] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2021] [Revised: 01/06/2022] [Accepted: 12/06/2021] [Indexed: 11/19/2022] Open
Abstract
In spite of its immutable susceptibility to penicillin, Treponema pallidum (T. pallidum) subsp. pallidum continues to cause millions of cases of syphilis each year worldwide, resulting in significant morbidity and mortality and underscoring the urgency of developing an effective vaccine to curtail the spread of the infection. Several technical challenges, including absence of an in vitro culture system until very recently, have hampered efforts to catalog the diversity of strains collected worldwide. Here, we provide near-complete genomes from 196 T. pallidum strains-including 191 T. pallidum subsp. pallidum-sequenced directly from patient samples collected from 8 countries and 6 continents. Maximum likelihood phylogeny revealed that samples from most sites were predominantly SS14 clade. However, 99% (84/85) of the samples from Madagascar formed two of the five distinct Nichols subclades. Although recombination was uncommon in the evolution of modern circulating strains, we found multiple putative recombination events between T. pallidum subsp. pallidum and subsp. endemicum, shaping the genomes of several subclades. Temporal analysis dated the most recent common ancestor of Nichols and SS14 clades to 1717 (95% HPD: 1543-1869), in agreement with other recent studies. Rates of SNP accumulation varied significantly among subclades, particularly among different Nichols subclades, and was associated in the Nichols A subclade with a C394F substitution in TP0380, a ERCC3-like DNA repair helicase. Our data highlight the role played by variation in genes encoding putative surface-exposed outer membrane proteins in defining separate lineages, and provide a critical resource for the design of broadly protective syphilis vaccines targeting surface antigens.
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Affiliation(s)
- Nicole A. P. Lieberman
- Department of Laboratory Medicine and Pathology, University of Washington, Seattle, Washington, United States of America
| | - Michelle J. Lin
- Department of Laboratory Medicine and Pathology, University of Washington, Seattle, Washington, United States of America
| | - Hong Xie
- Department of Laboratory Medicine and Pathology, University of Washington, Seattle, Washington, United States of America
| | - Lasata Shrestha
- Department of Laboratory Medicine and Pathology, University of Washington, Seattle, Washington, United States of America
| | - Tien Nguyen
- Department of Laboratory Medicine and Pathology, University of Washington, Seattle, Washington, United States of America
| | - Meei-Li Huang
- Department of Laboratory Medicine and Pathology, University of Washington, Seattle, Washington, United States of America
| | - Austin M. Haynes
- Department of Medicine, Division of Allergy and Infectious Diseases, University of Washington, Seattle, Washington, United States of America
| | - Emily Romeis
- Department of Medicine, Division of Allergy and Infectious Diseases, University of Washington, Seattle, Washington, United States of America
| | - Qian-Qiu Wang
- Institute of Dermatology, Chinese Academy of Medical Science & Peking Union Medical College, Beijing, China
- National Center for STD Control, China Centers for Disease Control and Prevention, Nanjing, China
| | - Rui-Li Zhang
- Department of Dermatology, The Second Affiliated Hospital of Nanjing Medical University, Nanjing, China
| | - Cai-Xia Kou
- Institute of Dermatology, Chinese Academy of Medical Science & Peking Union Medical College, Beijing, China
- National Center for STD Control, China Centers for Disease Control and Prevention, Nanjing, China
| | - Giulia Ciccarese
- Health Sciences Department, Section of Dermatology, San Martino University Hospital, Genoa, Italy
| | - Ivano Dal Conte
- STI Clinic, Infectious Diseases Unit, University of Turin, Turin, Italy
| | - Marco Cusini
- Fondazione IRCCS Ca’ Granda, Ospedale Maggiore Policlinico, Milan, Italy
| | - Francesco Drago
- Health Sciences Department, Section of Dermatology, San Martino University Hospital, Genoa, Italy
| | - Shu-ichi Nakayama
- Department of Bacteriology I, National Institute of Infectious Diseases, Tokyo, Japan
| | - Kenichi Lee
- Department of Bacteriology I, National Institute of Infectious Diseases, Tokyo, Japan
| | - Makoto Ohnishi
- Department of Bacteriology I, National Institute of Infectious Diseases, Tokyo, Japan
| | - Kelika A. Konda
- Unit of Health, Sexuality and Human Development and Laboratory of Sexual Health, Universidad Peruana Cayetano-Heredia, Lima, Peru
- Keck School of Medicine, University of Southern California, Los Angeles, California, United States of America
| | - Silver K. Vargas
- Unit of Health, Sexuality and Human Development and Laboratory of Sexual Health, Universidad Peruana Cayetano-Heredia, Lima, Peru
| | - Maria Eguiluz
- Unit of Health, Sexuality and Human Development and Laboratory of Sexual Health, Universidad Peruana Cayetano-Heredia, Lima, Peru
| | - Carlos F. Caceres
- Unit of Health, Sexuality and Human Development and Laboratory of Sexual Health, Universidad Peruana Cayetano-Heredia, Lima, Peru
| | - Jeffrey D. Klausner
- Keck School of Medicine, University of Southern California, Los Angeles, California, United States of America
| | - Oriol Mitjà
- Fight Aids and Infectious Diseases Foundation, Hospital Germans Trias i Pujol, Barcelona, Spain
- Lihir Medical Centre-International SOS, Newcrest Mining, Lihir Island, Papua New Guinea
| | - Anne Rompalo
- Department of Infectious Diseases, Johns Hopkins Medical Institutions, Baltimore, Maryland, United States of America
| | - Fiona Mulcahy
- Department of Genito Urinary Medicine and Infectious Diseases, St James’s Hospital, Dublin, Ireland
| | - Edward W. Hook
- Department of Medicine, University of Alabama, Birmingham, Birmingham, Alabama, United States of America
| | - Sheila A. Lukehart
- Department of Medicine, Division of Allergy and Infectious Diseases, University of Washington, Seattle, Washington, United States of America
- Department of Global Health, University of Washington, Seattle, Washington, United States of America
| | - Amanda M. Casto
- Department of Medicine, Division of Allergy and Infectious Diseases, University of Washington, Seattle, Washington, United States of America
- Vaccine and Infectious Disease Division, Fred Hutchinson Cancer Research Center, Seattle, Washington, United States of America
| | - Pavitra Roychoudhury
- Department of Laboratory Medicine and Pathology, University of Washington, Seattle, Washington, United States of America
- Vaccine and Infectious Disease Division, Fred Hutchinson Cancer Research Center, Seattle, Washington, United States of America
| | - Frank DiMaio
- Department of Biochemistry, University of Washington, Seattle, Washington, United States of America
| | - Lorenzo Giacani
- Department of Medicine, Division of Allergy and Infectious Diseases, University of Washington, Seattle, Washington, United States of America
- Department of Global Health, University of Washington, Seattle, Washington, United States of America
| | - Alexander L. Greninger
- Department of Laboratory Medicine and Pathology, University of Washington, Seattle, Washington, United States of America
- Vaccine and Infectious Disease Division, Fred Hutchinson Cancer Research Center, Seattle, Washington, United States of America
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14
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Lin MJ, Haynes AM, Addetia A, Lieberman NAP, Phung Q, Xie H, Nguyen TV, Molini BJ, Lukehart SA, Giacani L, Greninger AL. Longitudinal TprK profiling of in vivo and in vitro-propagated Treponema pallidum subsp. pallidum reveals accumulation of antigenic variants in absence of immune pressure. PLoS Negl Trop Dis 2021; 15:e0009753. [PMID: 34492041 PMCID: PMC8480903 DOI: 10.1371/journal.pntd.0009753] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2021] [Revised: 09/29/2021] [Accepted: 08/23/2021] [Indexed: 11/25/2022] Open
Abstract
Immune evasion by Treponema pallidum subspecies pallidum (T. pallidum) has been attributed to antigenic variation of its putative outer-membrane protein TprK. In TprK, amino acid diversity is confined to seven variable (V) regions, and generation of sequence diversity within the V regions occurs via a non-reciprocal segmental gene conversion mechanism where donor cassettes recombine into the tprK expression site. Although previous studies have shown the significant role of immune selection in driving accumulation of TprK variants, the contribution of baseline gene conversion activity to variant diversity is less clear. Here, combining longitudinal tprK deep sequencing of near clonal Chicago C from immunocompetent and immunosuppressed rabbits along with the newly developed in vitro cultivation system for T. pallidum, we directly characterized TprK alleles in the presence and absence of immune selection. Our data confirm significantly greater sequence diversity over time within the V6 region during syphilis infection in immunocompetent rabbits compared to immunosuppressed rabbits, consistent with previous studies on the role of TprK in evasion of the host immune response. Compared to strains grown in immunocompetent rabbits, strains passaged in vitro displayed low level changes in allele frequencies of TprK variable region sequences similar to that of strains passaged in immunosuppressed rabbits. Notably, we found significantly increased rates of V6 allele generation relative to other variable regions in in vitro cultivated T, pallidum strains, illustrating that the diversity within these hypervariable regions occurs in the complete absence of immune selection. Together, our results demonstrate antigenic variation in T. pallidum can be studied in vitro and occurs even in the complete absence of immune pressure, allowing the T. pallidum population to continuously evade the immune system of the infected host.
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Affiliation(s)
- Michelle J. Lin
- Department of Laboratory Medicine and Pathology, University of Washington, Seattle, Washington, United States of America
| | - Austin M. Haynes
- Pathobiology Graduate Program, University of Washington, Seattle, Washington, United States of America
| | - Amin Addetia
- Department of Laboratory Medicine and Pathology, University of Washington, Seattle, Washington, United States of America
- Molecular and Cellular Biology Graduate Program, University of Washington, Seattle, Washington, United States of America
| | - Nicole A. P. Lieberman
- Department of Laboratory Medicine and Pathology, University of Washington, Seattle, Washington, United States of America
| | - Quynh Phung
- Department of Laboratory Medicine and Pathology, University of Washington, Seattle, Washington, United States of America
| | - Hong Xie
- Department of Laboratory Medicine and Pathology, University of Washington, Seattle, Washington, United States of America
| | - Tien V. Nguyen
- Department of Laboratory Medicine and Pathology, University of Washington, Seattle, Washington, United States of America
| | - Barbara J. Molini
- Department of Medicine, Division of Allergy and Infectious Diseases, University of Washington, Seattle, Washington, United States of America
| | - Sheila A. Lukehart
- Department of Medicine, Division of Allergy and Infectious Diseases, University of Washington, Seattle, Washington, United States of America
- Department of Global Health, University of Washington, Seattle, Washington, United States of America
| | - Lorenzo Giacani
- Department of Medicine, Division of Allergy and Infectious Diseases, University of Washington, Seattle, Washington, United States of America
| | - Alexander L. Greninger
- Department of Laboratory Medicine and Pathology, University of Washington, Seattle, Washington, United States of America
- Vaccine and Infectious Disease Division, Fred Hutchinson Cancer Research Center, Seattle, Washington, United States of America
- * E-mail:
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