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Zhang T, Chien RC, Budachetri K, Lin M, Boyaka P, Huang W, Rikihisa Y. Ehrlichia effector TRP120 manipulates bacteremia to facilitate tick acquisition. mBio 2024; 15:e0047624. [PMID: 38501870 PMCID: PMC11005420 DOI: 10.1128/mbio.00476-24] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2024] [Accepted: 03/03/2024] [Indexed: 03/20/2024] Open
Abstract
Ehrlichia species are obligatory intracellular bacteria that cause a potentially fatal disease, human ehrlichiosis. The biomolecular mechanisms of tick acquisition of Ehrlichia and transmission between ticks and mammals are poorly understood. Ehrlichia japonica infection of mice recapitulates the full spectrum of human ehrlichiosis. We compared the pathogenicity and host acquisition of wild-type E. japonica with an isogenic transposon mutant of E. japonica that lacks tandem repeat protein 120 (TRP120) (ΔTRP120). Both wild-type and ΔTRP120 E. japonica proliferated similarly in cultures of mammalian and tick cells. Upon inoculation into mice, both wild-type and ΔTRP120 E. japonica multiplied to high levels in various tissues, with similar clinical chemistry and hematologic changes, proinflammatory cytokine induction, and fatal disease. However, the blood levels of ΔTRP120 E. japonica were almost undetectable within 24 h, whereas the levels of the wild type increased exponentially. Greater than 90% of TRP120 was released from infected cells into the culture medium. Mouse blood monocytes exposed to native TRP120 from culture supernatants showed significantly reduced cell surface expression of the transmigration-related markers Ly6C and CD11b. Larval ticks attached to mice infected with either wild-type or ΔTRP120 E. japonica imbibed similar amounts of blood and subsequently molted to nymphs at similar rates. However, unlike wild-type E. japonica, the ΔTRP120 mutant was minimally acquired by larval ticks and subsequent molted nymphs and, thus, failed to transmit to naïve mice. Thus, TRP120 is required for bacteremia but not disease. These findings suggest a novel mechanism whereby an obligatory intracellular bacterium manipulates infected blood monocytes to sustain the tick-mammal transmission cycle. IMPORTANCE Effective prevention of tick-borne diseases such as human ehrlichiosis requires an understanding of how disease-causing organisms are acquired. Ehrlichia species are intracellular bacteria that require infection of both mammals and ticks, involving cycles of transmission between them. Mouse models of ehrlichiosis and tick-mouse transmission can advance our fundamental understanding of the pathogenesis and prevention of ehrlichiosis. Herein, a mutant of Ehrlichia japonica was used to investigate the role of a single Ehrlichia factor, named tandem repeat protein 120 (TRP120), in infection of mammalian and tick cells in culture, infection and disease progression in mice, and tick acquisition of E. japonica from infected mice. Our results suggest that TRP120 is necessary only for Ehrlichia proliferation in circulating mouse blood and ongoing bacteremia to permit Ehrlichia acquisition by ticks. This study provides new insights into the importance of bacterial factors in regulating bacteremia, which may facilitate tick acquisition of pathogens.
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Affiliation(s)
- Tsian Zhang
- Department of Veterinary Biosciences, The Ohio State University, Columbus, Ohio, USA
| | - Rory C. Chien
- Department of Veterinary Biosciences, The Ohio State University, Columbus, Ohio, USA
| | - Khemraj Budachetri
- Department of Veterinary Biosciences, The Ohio State University, Columbus, Ohio, USA
| | - Mingqun Lin
- Department of Veterinary Biosciences, The Ohio State University, Columbus, Ohio, USA
| | - Prosper Boyaka
- Department of Veterinary Biosciences, The Ohio State University, Columbus, Ohio, USA
| | - Weiyan Huang
- Department of Veterinary Biosciences, The Ohio State University, Columbus, Ohio, USA
| | - Yasuko Rikihisa
- Department of Veterinary Biosciences, The Ohio State University, Columbus, Ohio, USA
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Dong L, Li Y, Yang C, Gong J, Zhu W, Huang Y, Kong M, Zhao L, Wang F, Lu S, Pu J, Yang J. Species-level microbiota of ticks and fleas from Marmota himalayana in the Qinghai-Tibet Plateau. Front Microbiol 2023; 14:1188155. [PMID: 37415819 PMCID: PMC10320725 DOI: 10.3389/fmicb.2023.1188155] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2023] [Accepted: 05/31/2023] [Indexed: 07/08/2023] Open
Abstract
Introduction Ticks and fleas, as blood-sucking arthropods, carry and transmit various zoonotic diseases. In the natural plague foci of China, monitoring of Yersinia pestis has been continuously conducted in Marmota himalayana and other host animals, whereas other pathogens carried by vectors are rarely concerned in the Qinghai-Tibet Plateau. Methods In this study, we investigated the microbiota of ticks and fleas sampling from M. himalayana in the Qinghai-Tibet Plateau, China by metataxonomics combined with metagenomic methods. Results By metataxonomic approach based on full-length 16S rDNA amplicon sequencing and operational phylogenetic unit (OPU) analyses, we described the microbiota community of ticks and fleas at the species level, annotated 1,250 OPUs in ticks, including 556 known species and 492 potentially new species, accounting for 48.50% and 41.71% of the total reads in ticks, respectively. A total of 689 OPUs were detected in fleas, consisting of 277 known species (40.62% of the total reads in fleas) and 294 potentially new species (56.88%). At the dominant species categories, we detected the Anaplasma phagocytophilum (OPU 421) and potentially pathogenic new species of Wolbachia, Ehrlichia, Rickettsia, and Bartonella. Using shotgun sequencing, we obtained 10 metagenomic assembled genomes (MAGs) from vector samples, including a known species (Providencia heimbachae DFT2), and six new species affliated to four known genera, i.e., Wolbachia, Mumia, Bartonella, and Anaplasma. By the phylogenetic analyses based on full-length 16S rRNA genes and core genes, we identified that ticks harbored pathogenic A. phagocytophilum. Moreover, these potentially pathogenic novel species were more closely related to Ehrlichia muris, Ehrlichia muris subsp. eauclairensis, Bartonella rochalimae, and Rickettsia limoniae, respectively. The OPU 422 Ehrlichia sp1 was most related to Ehrlichia muris and Ehrlichia muris subsp. eauclairensis. The OPU 230 Bartonella sp1 and Bartonella spp. (DTF8 and DTF9) was clustered with Bartonella rochalimae. The OPU 427 Rickettsia sp1 was clustered with Rickettsia limoniae. Discussion The findings of the study have advanced our understanding of the potential pathogen groups of vectors in marmot (Marmota himalayana) in the Qinghai-Tibet Plateau.
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Affiliation(s)
- Lingzhi Dong
- Department of Epidemiology, School of Public Health, Shanxi Medical University, Taiyuan, China
- State Key Laboratory of Infectious Disease Prevention and Control, Chinese Center for Disease Control and Prevention, National Institute for Communicable Disease Control and Prevention, Beijing, China
| | - Yaben Li
- Department of Epidemiology, School of Public Health, Shanxi Medical University, Taiyuan, China
- State Key Laboratory of Infectious Disease Prevention and Control, Chinese Center for Disease Control and Prevention, National Institute for Communicable Disease Control and Prevention, Beijing, China
| | - Caixin Yang
- Department of Epidemiology, School of Public Health, Shanxi Medical University, Taiyuan, China
- State Key Laboratory of Infectious Disease Prevention and Control, Chinese Center for Disease Control and Prevention, National Institute for Communicable Disease Control and Prevention, Beijing, China
| | - Jian Gong
- Department of Epidemiology, School of Public Health, Shanxi Medical University, Taiyuan, China
- State Key Laboratory of Infectious Disease Prevention and Control, Chinese Center for Disease Control and Prevention, National Institute for Communicable Disease Control and Prevention, Beijing, China
| | - Wentao Zhu
- Department of Infectious Diseases and Clinical Microbiology, Beijing Chao-Yang Hospital, Capital Medical University, Beijing, China
| | - Yuyuan Huang
- State Key Laboratory of Infectious Disease Prevention and Control, Chinese Center for Disease Control and Prevention, National Institute for Communicable Disease Control and Prevention, Beijing, China
| | - Mimi Kong
- Department of Epidemiology, School of Public Health, Shanxi Medical University, Taiyuan, China
- State Key Laboratory of Infectious Disease Prevention and Control, Chinese Center for Disease Control and Prevention, National Institute for Communicable Disease Control and Prevention, Beijing, China
| | - Lijun Zhao
- Department of Epidemiology, School of Public Health, Shanxi Medical University, Taiyuan, China
- State Key Laboratory of Infectious Disease Prevention and Control, Chinese Center for Disease Control and Prevention, National Institute for Communicable Disease Control and Prevention, Beijing, China
| | - Feifei Wang
- Department of Epidemiology, School of Public Health, Shanxi Medical University, Taiyuan, China
- State Key Laboratory of Infectious Disease Prevention and Control, Chinese Center for Disease Control and Prevention, National Institute for Communicable Disease Control and Prevention, Beijing, China
| | - Shan Lu
- Department of Epidemiology, School of Public Health, Shanxi Medical University, Taiyuan, China
- State Key Laboratory of Infectious Disease Prevention and Control, Chinese Center for Disease Control and Prevention, National Institute for Communicable Disease Control and Prevention, Beijing, China
- Research Units of Discovery of Unknown Bacteria and Function, Chinese Academy of Medical Sciences, Beijing, China
| | - Ji Pu
- Department of Epidemiology, School of Public Health, Shanxi Medical University, Taiyuan, China
- State Key Laboratory of Infectious Disease Prevention and Control, Chinese Center for Disease Control and Prevention, National Institute for Communicable Disease Control and Prevention, Beijing, China
| | - Jing Yang
- Department of Epidemiology, School of Public Health, Shanxi Medical University, Taiyuan, China
- State Key Laboratory of Infectious Disease Prevention and Control, Chinese Center for Disease Control and Prevention, National Institute for Communicable Disease Control and Prevention, Beijing, China
- Research Units of Discovery of Unknown Bacteria and Function, Chinese Academy of Medical Sciences, Beijing, China
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Fisher DJ, Beare PA. Recent advances in genetic systems in obligate intracellular human-pathogenic bacteria. Front Cell Infect Microbiol 2023; 13:1202245. [PMID: 37404720 PMCID: PMC10315504 DOI: 10.3389/fcimb.2023.1202245] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2023] [Accepted: 05/22/2023] [Indexed: 07/06/2023] Open
Abstract
The ability to genetically manipulate a pathogen is fundamental to discovering factors governing host-pathogen interactions at the molecular level and is critical for devising treatment and prevention strategies. While the genetic "toolbox" for many important bacterial pathogens is extensive, approaches for modifying obligate intracellular bacterial pathogens were classically limited due in part to the uniqueness of their obligatory lifestyles. Many researchers have confronted these challenges over the past two and a half decades leading to the development of multiple approaches to construct plasmid-bearing recombinant strains and chromosomal gene inactivation and deletion mutants, along with gene-silencing methods enabling the study of essential genes. This review will highlight seminal genetic achievements and recent developments (past 5 years) for Anaplasma spp., Rickettsia spp., Chlamydia spp., and Coxiella burnetii including progress being made for the still intractable Orientia tsutsugamushi. Alongside commentary of the strengths and weaknesses of the various approaches, future research directions will be discussed to include methods for C. burnetii that should have utility in the other obligate intracellular bacteria. Collectively, the future appears bright for unraveling the molecular pathogenic mechanisms of these significant pathogens.
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Affiliation(s)
- Derek J. Fisher
- School of Biological Sciences, Southern Illinois University, Carbondale, IL, United States
| | - Paul A. Beare
- Rocky Mountain Laboratory, National Institute of Health, Hamilton, MT, United States
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Wang Y, Nair ADS, Alhassan A, Jaworski DC, Liu H, Trinkl K, Hove P, Ganta CK, Burkhardt N, Munderloh UG, Ganta RR. Multiple Ehrlichia chaffeensis Genes Critical for Its Persistent Infection in a Vertebrate Host Are Identified by Random Mutagenesis Coupled with In Vivo Infection Assessment. Infect Immun 2020; 88:e00316-20. [PMID: 32747600 PMCID: PMC7504954 DOI: 10.1128/iai.00316-20] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2020] [Accepted: 07/23/2020] [Indexed: 12/14/2022] Open
Abstract
Ehrlichia chaffeensis, a tick-transmitted obligate intracellular rickettsial agent, causes human monocytic ehrlichiosis. In recent reports, we described substantial advances in developing random and targeted gene disruption methods to investigate the functions of E. chaffeensis genes. We reported earlier that the Himar1 transposon-based random mutagenesis is a valuable tool in defining E. chaffeensis genes critical for its persistent growth in vivo in reservoir and incidental hosts. The method also aided in extending studies focused on vaccine development and immunity. Here, we describe the generation and mapping of 55 new mutations. To define the critical nature of the bacterial genes, infection experiments were carried out in the canine host with pools of mutant organisms. Infection evaluation in the physiologically relevant host by molecular assays and by xenodiagnoses allowed the identification of many proteins critical for the pathogen's persistent in vivo growth. Genes encoding proteins involved in biotin biosynthesis, protein synthesis and fatty acid biosynthesis, DNA repair, electron transfer, and a component of a multidrug resistance (MDR) efflux pump were concluded to be essential for the pathogen's in vivo growth. Three known immunodominant membrane proteins, i.e., two 28-kDa outer membrane proteins (P28/OMP) and a 120-kDa surface protein, were also recognized as necessary for the pathogen's obligate intracellular life cycle. The discovery of many E. chaffeensis proteins crucial for its continuous in vivo growth will serve as a major resource for investigations aimed at defining pathogenesis and developing novel therapeutics for this and related pathogens of the rickettsial family Anaplasmataceae.
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Affiliation(s)
- Ying Wang
- Center of Excellence for Vector-Borne Diseases (CEVBD), Department of Diagnostic Medicine/Pathobiology, College of Veterinary Medicine, Kansas State University, Manhattan, Kansas, USA
| | - Arathy D S Nair
- Center of Excellence for Vector-Borne Diseases (CEVBD), Department of Diagnostic Medicine/Pathobiology, College of Veterinary Medicine, Kansas State University, Manhattan, Kansas, USA
| | - Andy Alhassan
- Center of Excellence for Vector-Borne Diseases (CEVBD), Department of Diagnostic Medicine/Pathobiology, College of Veterinary Medicine, Kansas State University, Manhattan, Kansas, USA
- Department of Pathobiology, School of Veterinary Medicine, St. George's University, West Indies, Grenada
| | - Deborah C Jaworski
- Center of Excellence for Vector-Borne Diseases (CEVBD), Department of Diagnostic Medicine/Pathobiology, College of Veterinary Medicine, Kansas State University, Manhattan, Kansas, USA
| | - Huitao Liu
- Center of Excellence for Vector-Borne Diseases (CEVBD), Department of Diagnostic Medicine/Pathobiology, College of Veterinary Medicine, Kansas State University, Manhattan, Kansas, USA
| | - Kathleen Trinkl
- Center of Excellence for Vector-Borne Diseases (CEVBD), Department of Diagnostic Medicine/Pathobiology, College of Veterinary Medicine, Kansas State University, Manhattan, Kansas, USA
| | - Paidashe Hove
- Center of Excellence for Vector-Borne Diseases (CEVBD), Department of Diagnostic Medicine/Pathobiology, College of Veterinary Medicine, Kansas State University, Manhattan, Kansas, USA
- Department of Pathobiology, School of Veterinary Medicine, St. George's University, West Indies, Grenada
| | - Charan K Ganta
- Center of Excellence for Vector-Borne Diseases (CEVBD), Department of Diagnostic Medicine/Pathobiology, College of Veterinary Medicine, Kansas State University, Manhattan, Kansas, USA
| | - Nicole Burkhardt
- Department of Entomology, University of Minnesota, St. Paul, Minnesota, USA
| | - Ulrike G Munderloh
- Department of Entomology, University of Minnesota, St. Paul, Minnesota, USA
| | - Roman R Ganta
- Center of Excellence for Vector-Borne Diseases (CEVBD), Department of Diagnostic Medicine/Pathobiology, College of Veterinary Medicine, Kansas State University, Manhattan, Kansas, USA
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