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Wang J, Du LF, Zhang MZ, Wei W, Chen ZY, Zhang X, Xiong T, Wang ZF, Xia LY, Jiang JF, Li WJ, Zhu DY, Jia N, Cao WC. Stomach as the target organ of Rickettsia heilongjiangensis infection in C57BL/6 mice identified by click chemistry. Commun Biol 2024; 7:784. [PMID: 38951577 PMCID: PMC11217389 DOI: 10.1038/s42003-024-06468-z] [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: 12/19/2023] [Accepted: 06/19/2024] [Indexed: 07/03/2024] Open
Abstract
Spotted fever group rickettsiae (SFGR) are obligate intracellular bacteria that cause spotted fever. The limitations of gene manipulation pose great challenges to studying the infection mechanisms of Rickettsia. By combining bioorthogonal metabolism and click chemistry, we developed a method to label R. heilongjiangensis via azide moieties and achieved rapid pathogen localization without complex procedures. Moreover, we constructed a C57BL/6 mice infection model by simulating tick bites and discovered that the stomach is the target organ of R. heilongjiangensis infection through in vivo imaging systems, which explained the occurrence of gastrointestinal symptoms following R. heilongjiangensis infection in some cases. This study offers a unique perspective for subsequent investigations into the pathogenic mechanisms of SFGR and identifies a potential target organ for R. heilongjiangensis.
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Affiliation(s)
- Juan Wang
- School of Public Health and Health Management, Gannan Medical University, Ganzhou, 341000, Jiangxi, P. R. China
- State Key Laboratory of Pathogen and Biosecurity, Academy of Military Medical Sciences, Beijing, 100071, P.R. China
| | - Li-Feng Du
- Institute of EcoHealth, School of Public Health, Shandong University, 44 Wenhuaxi Street, Jinan, 250012, Shandong, P.R. China
| | - Ming-Zhu Zhang
- Institute of EcoHealth, School of Public Health, Shandong University, 44 Wenhuaxi Street, Jinan, 250012, Shandong, P.R. China
| | - Wei Wei
- State Key Laboratory of Pathogen and Biosecurity, Academy of Military Medical Sciences, Beijing, 100071, P.R. China
| | - Zi-Yun Chen
- State Key Laboratory of Pathogen and Biosecurity, Academy of Military Medical Sciences, Beijing, 100071, P.R. China
- School of Public Health, Fujian Medical University, Fuzhou, Fujian, 350122, China
| | - Xu Zhang
- Guangdong Key Laboratory of Nanomedicine CAS-HK Joint Lab of Biomaterials, Shenzhen Engineering Laboratory of Nanomedicine and Nanoformulations Shenzhen Institute of Advanced Technology (SIAT) Chinese Academy of Sciences, Shenzhen, 518055, P. R. China
| | - Tao Xiong
- State Key Laboratory of Pathogen and Biosecurity, Academy of Military Medical Sciences, Beijing, 100071, P.R. China
| | - Zhen-Fei Wang
- Changchun Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Changchun, China
| | - Luo-Yuan Xia
- State Key Laboratory of Pathogen and Biosecurity, Academy of Military Medical Sciences, Beijing, 100071, P.R. China
- Institute of EcoHealth, School of Public Health, Shandong University, 44 Wenhuaxi Street, Jinan, 250012, Shandong, P.R. China
| | - Jia-Fu Jiang
- State Key Laboratory of Pathogen and Biosecurity, Academy of Military Medical Sciences, Beijing, 100071, P.R. China.
| | - Wen-Jun Li
- Guangdong Key Laboratory of Nanomedicine CAS-HK Joint Lab of Biomaterials, Shenzhen Engineering Laboratory of Nanomedicine and Nanoformulations Shenzhen Institute of Advanced Technology (SIAT) Chinese Academy of Sciences, Shenzhen, 518055, P. R. China.
| | - Dai-Yun Zhu
- State Key Laboratory of Pathogen and Biosecurity, Academy of Military Medical Sciences, Beijing, 100071, P.R. China.
| | - Na Jia
- State Key Laboratory of Pathogen and Biosecurity, Academy of Military Medical Sciences, Beijing, 100071, P.R. China.
| | - Wu-Chun Cao
- State Key Laboratory of Pathogen and Biosecurity, Academy of Military Medical Sciences, Beijing, 100071, P.R. China.
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Liang Y, Wang H, Sun K, Sun J, Soong L. Lack of the IFN-γ signal leads to lethal Orientia tsutsugamushi infection in mice with skin eschar lesions. PLoS Pathog 2024; 20:e1012020. [PMID: 38743761 PMCID: PMC11125519 DOI: 10.1371/journal.ppat.1012020] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2024] [Revised: 05/24/2024] [Accepted: 04/30/2024] [Indexed: 05/16/2024] Open
Abstract
Scrub typhus is an acute febrile disease due to Orientia tsutsugamushi (Ot) infection and can be life-threatening with organ failure, hemorrhage, and fatality. Yet, little is known as to how the host reacts to Ot bacteria at early stages of infection; no reports have addressed the functional roles of type I versus type II interferon (IFN) responses in scrub typhus. In this study, we used comprehensive intradermal (i.d.) inoculation models and two clinically predominant Ot strains (Karp and Gilliam) to uncover early immune events. Karp infection induced sequential expression of Ifnb and Ifng in inflamed skin and draining lymph nodes at days 1 and 3 post-infection. Using double Ifnar1-/-Ifngr1-/- and Stat1-/- mice, we found that deficiency in IFN/STAT1 signaling resulted in lethal infection with profound pathology and skin eschar lesions, which resembled to human scrub typhus. Further analyses demonstrated that deficiency in IFN-γ, but not IFN-I, resulted in impaired NK cell and macrophage activation and uncontrolled bacterial growth and dissemination, leading to metabolic dysregulation, excessive inflammatory cell infiltration, and exacerbated tissue damage. NK cells were found to be the major cellular source of innate IFN-γ, contributing to the initial Ot control in the draining lymph nodes. In vitro studies with dendritic cell cultures revealed a superior antibacterial effect offered by IFN-γ than IFN-β. Comparative in vivo studies with Karp- and Gilliam-infection revealed a crucial role of IFN-γ signaling in protection against progression of eschar lesions and Ot infection lethality. Additionally, our i.d. mouse models of lethal infection with eschar lesions are promising tools for immunological study and vaccine development for scrub typhus.
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Affiliation(s)
- Yuejin Liang
- Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, Texas, United States of America
- Institute for Human Infections and Immunity, University of Texas Medical Branch, Galveston, Texas, United States of America
- Center for Tropical Diseases, University of Texas Medical Branch, Galveston, Texas, United States of America
| | - Hui Wang
- Institute for Human Infections and Immunity, University of Texas Medical Branch, Galveston, Texas, United States of America
- Department of Pathology, University of Texas Medical Branch, Galveston, Texas, United States of America
| | - Keer Sun
- Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, Texas, United States of America
- Institute for Human Infections and Immunity, University of Texas Medical Branch, Galveston, Texas, United States of America
| | - Jiaren Sun
- Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, Texas, United States of America
- Institute for Human Infections and Immunity, University of Texas Medical Branch, Galveston, Texas, United States of America
- Department of Pathology, University of Texas Medical Branch, Galveston, Texas, United States of America
| | - Lynn Soong
- Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, Texas, United States of America
- Institute for Human Infections and Immunity, University of Texas Medical Branch, Galveston, Texas, United States of America
- Center for Tropical Diseases, University of Texas Medical Branch, Galveston, Texas, United States of America
- Department of Pathology, University of Texas Medical Branch, Galveston, Texas, United States of America
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Balasubramanian T, Sambath U, Radja RD, Thangaraj G, Devaraju P, Srinivasan L, Srinivasan P, Nair MG, Raja K, Lakkawar AW, Soong L. Pathological Responses in Asian House Shrews ( Suncus murinus) to the Naturally Acquired Orientia tsutsugamushi Infection. Microorganisms 2024; 12:748. [PMID: 38674692 PMCID: PMC11051718 DOI: 10.3390/microorganisms12040748] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2024] [Revised: 03/28/2024] [Accepted: 04/03/2024] [Indexed: 04/28/2024] Open
Abstract
Scrub typhus is a re-emerging disease caused by Orientia tsutsugamushi, transmitted by mites belonging to the family Trombiculidae. Humans and rodents acquire the infection by the bite of larval mites/chiggers. Suncus murinus, the Asian house shrew, has been reported to harbor the vector mites and has been naturally infected with O. tsutsugamushi. The present study aimed to localize and record O. tsutsugamushi in the tissues and the host response in shrews naturally infected with O. tsutsugamushi. Sheehan's modified May-Grunwald Giemsa staining was carried out in 365 tissues from 87 animals, and rickettsiae were documented in 87 tissues from 20 animals. Immunohistochemical (IHC) staining, using polyclonal antibodies raised against selected epitopes of the 56-kDa antigen, was carried out, and 81/87 tissue sections were tested positive for O. tsutsugamushi. By IHC, in addition to the endothelium, the pathogen was also demonstrated by IHC in cardiomyocytes, the bronchiolar epithelium, stroma of the lungs, hepatocytes, the bile duct epithelium, the epithelium and goblet cells of intestine, the tubular epithelium of the kidney, and splenic macrophages. Furthermore, the pathogen was confirmed by real-time PCR using blood (n = 20) and tissues (n = 81) of the IHC-positive animals. None of the blood samples and only 22 out of 81 IHC-positive tissues were tested positive by PCR. By nucleotide sequencing of the 56-kDa gene, Gilliam and Karp strains were found circulating among these animals. Although these bacterial strains are highly virulent and cause a wide range of pathological alterations, hence exploring their adaptive mechanisms of survival in shrews will be of significance. Given that the pathogen localizes in various organs following a transient bacteremia, we recommend the inclusion of tissues from the heart, lung, intestine, and kidney of reservoir animals, in addition to blood samples, for future molecular surveillance of scrub typhus.
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Affiliation(s)
- Tharani Balasubramanian
- Department of Veterinary Pathology, Rajiv Gandhi Institute of Veterinary Education and Research, Kurumbapet, Puducherry 605009, India; (T.B.); (U.S.); (M.G.N.); (K.R.); (A.W.L.)
| | - Uma Sambath
- Department of Veterinary Pathology, Rajiv Gandhi Institute of Veterinary Education and Research, Kurumbapet, Puducherry 605009, India; (T.B.); (U.S.); (M.G.N.); (K.R.); (A.W.L.)
| | - Ranjana Devi Radja
- Unit of One Health, ICMR—Vector Control Research Centre, Indira Nagar, Puducherry 605006, India; (R.D.R.); (G.T.); (L.S.); (P.S.)
| | - Gowdham Thangaraj
- Unit of One Health, ICMR—Vector Control Research Centre, Indira Nagar, Puducherry 605006, India; (R.D.R.); (G.T.); (L.S.); (P.S.)
| | - Panneer Devaraju
- Unit of One Health, ICMR—Vector Control Research Centre, Indira Nagar, Puducherry 605006, India; (R.D.R.); (G.T.); (L.S.); (P.S.)
| | - Lakshmy Srinivasan
- Unit of One Health, ICMR—Vector Control Research Centre, Indira Nagar, Puducherry 605006, India; (R.D.R.); (G.T.); (L.S.); (P.S.)
| | - Pushpa Srinivasan
- Unit of One Health, ICMR—Vector Control Research Centre, Indira Nagar, Puducherry 605006, India; (R.D.R.); (G.T.); (L.S.); (P.S.)
| | - Madhavan Gopalakrishnan Nair
- Department of Veterinary Pathology, Rajiv Gandhi Institute of Veterinary Education and Research, Kurumbapet, Puducherry 605009, India; (T.B.); (U.S.); (M.G.N.); (K.R.); (A.W.L.)
| | - Kumar Raja
- Department of Veterinary Pathology, Rajiv Gandhi Institute of Veterinary Education and Research, Kurumbapet, Puducherry 605009, India; (T.B.); (U.S.); (M.G.N.); (K.R.); (A.W.L.)
| | - Avinash Warundeo Lakkawar
- Department of Veterinary Pathology, Rajiv Gandhi Institute of Veterinary Education and Research, Kurumbapet, Puducherry 605009, India; (T.B.); (U.S.); (M.G.N.); (K.R.); (A.W.L.)
| | - Lynn Soong
- Department of Microbiology and Immunology, Institute for Human Infections & Immunity, University of Texas Medical Branch at Galveston, Galveston, TX 77555, USA
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Gonzales C, Liang Y, Fisher J, Card G, Sun J, Soong L. Alterations in germinal center formation and B cell activation during severe Orientia tsutsugamushi infection in mice. PLoS Negl Trop Dis 2023; 17:e0011090. [PMID: 37146079 PMCID: PMC10191367 DOI: 10.1371/journal.pntd.0011090] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2023] [Revised: 05/17/2023] [Accepted: 04/17/2023] [Indexed: 05/07/2023] Open
Abstract
Scrub typhus is a poorly studied but life-threatening disease caused by the intracellular bacterium Orientia tsutsugamushi (Ot). Cellular and humoral immunity in Ot-infected patients is not long-lasting, waning as early as one-year post-infection; however, its underlying mechanisms remain unclear. To date, no studies have examined germinal center (GC) or B cell responses in Ot-infected humans or experimental animals. This study was aimed at evaluating humoral immune responses at acute stages of severe Ot infection and possible mechanisms underlying B cell dysfunction. Following inoculation with Ot Karp, a clinically dominant strain known to cause lethal infection in C57BL/6 mice, we measured antigen-specific antibody titers, revealing IgG2c as the dominant isotype induced by infection. Splenic GC responses were evaluated by immunohistology, co-staining for B cells (B220), T cells (CD3), and GCs (GL-7). Organized GCs were evident at day 4 post-infection (D4), but they were nearly absent at D8, accompanied by scattered T cells throughout splenic tissues. Flow cytometry revealed comparable numbers of GC B cells and T follicular helper (Tfh) cells at D4 and D8, indicating that GC collapse was not due to excessive death of these cell subtypes at D8. B cell RNAseq analysis revealed significant differences in expression of genes associated with B cell adhesion and co-stimulation at D8 versus D4. The significant downregulation of S1PR2 (a GC-specific adhesion gene) was most evident at D8, correlating with disrupted GC formation. Signaling pathway analysis uncovered downregulation of 71% of B cell activation genes at D8, suggesting attenuation of B cell activation during severe infection. This is the first study showing the disruption of B/T cell microenvironment and dysregulation of B cell responses during Ot infection, which may help understand the transient immunity associated with scrub typhus.
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Affiliation(s)
- Casey Gonzales
- Department of Pathology, University of Texas Medical Branch, Galveston, Texas, United States of America
| | - Yuejin Liang
- Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, Texas, United States of America
- Institute of Human Infections and Immunity, University of Texas Medical Branch, Galveston, Texas, United States of America
| | - James Fisher
- Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, Texas, United States of America
| | - Galen Card
- Department of Pathology, University of Texas Medical Branch, Galveston, Texas, United States of America
| | - Jiaren Sun
- Department of Pathology, University of Texas Medical Branch, Galveston, Texas, United States of America
- Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, Texas, United States of America
- Institute of Human Infections and Immunity, University of Texas Medical Branch, Galveston, Texas, United States of America
| | - Lynn Soong
- Department of Pathology, University of Texas Medical Branch, Galveston, Texas, United States of America
- Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, Texas, United States of America
- Institute of Human Infections and Immunity, University of Texas Medical Branch, Galveston, Texas, United States of America
- Sealy Institute for Vaccine Sciences, University of Texas Medical Branch, Galveston, Texas, United States of America
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Liang Y, Wang H, Gonzales C, Thiriot J, Sunyakumthorn P, Melby PC, Sun J, Soong L. CCR7/dendritic cell axis mediates early bacterial dissemination in Orientia tsutsugamushi-infected mice. Front Immunol 2022; 13:1061031. [PMID: 36618364 PMCID: PMC9813216 DOI: 10.3389/fimmu.2022.1061031] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2022] [Accepted: 12/09/2022] [Indexed: 12/24/2022] Open
Abstract
Scrub typhus is a life-threatening zoonosis caused by the obligate intracellular bacterium Orientia tsutsugamushi (Ot) that is transmitted by the infected larvae of trombiculid mites. However, the mechanism by which Ot disseminates from the bite site to visceral organs remains unclear; host innate immunity against bacterial dissemination and replication during early infection is poorly understood. In this study, by using an intradermal infection mouse model and fluorescent probe-labeled Ot, we assessed the dynamic pattern of innate immune cell responses at the inoculation site. We found that neutrophils were the first responders to Ot infection and migrated into the skin for bacterial uptake. Ot infection greatly induced neutrophil activation, and Ot-neutrophil interaction remarkably promoted cell death both in vitro and in vivo. Depletion of neutrophils did not alter bacterial dissemination in mice, as evidenced by similar bacterial burdens in the skin and draining lymph nodes (dLN) at day 3, as well as in the lungs and brains at day 14, as compared to the control mice. Instead, dendritic cells (DCs) and macrophages played a role as a Trojan horse and transmitted Ot from the skin into dLN. Importantly, the absence of homing receptor CCR7 or neutralization of its ligand, CCL21, significantly impaired DC migration, resulting in reduced bacterial burdens in dLN. Taken together, our study sheds light on a CCR7/dendritic cell-mediated mechanism of early Ot dissemination and provides new insights into therapeutic and vaccine development strategies for scrub typhus.
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Affiliation(s)
- Yuejin Liang
- Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, TX, United States
- Institute for Human Infections and Immunity, University of Texas Medical Branch, Galveston, TX, United States
| | - Hui Wang
- Institute for Human Infections and Immunity, University of Texas Medical Branch, Galveston, TX, United States
- Department of Pathology, University of Texas Medical Branch, Galveston, TX, United States
| | - Casey Gonzales
- Department of Pathology, University of Texas Medical Branch, Galveston, TX, United States
| | - Joseph Thiriot
- Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, TX, United States
| | - Piyanate Sunyakumthorn
- Department of Veterinary Medicine, United States Army Medical Directorate, Armed Forces Research Institute of Medical Sciences (USAMD-AFRIMS), Bangkok, Thailand
| | - Peter C. Melby
- Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, TX, United States
- Institute for Human Infections and Immunity, University of Texas Medical Branch, Galveston, TX, United States
- Department of Pathology, University of Texas Medical Branch, Galveston, TX, United States
- Department of Internal Medicine, University of Texas Medical Branch, Galveston, TX, United States
| | - Jiaren Sun
- Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, TX, United States
- Institute for Human Infections and Immunity, University of Texas Medical Branch, Galveston, TX, United States
- Department of Pathology, University of Texas Medical Branch, Galveston, TX, United States
| | - Lynn Soong
- Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, TX, United States
- Institute for Human Infections and Immunity, University of Texas Medical Branch, Galveston, TX, United States
- Department of Pathology, University of Texas Medical Branch, Galveston, TX, United States
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Thiriot J, Liang Y, Fisher J, Walker DH, Soong L. Host transcriptomic profiling of CD-1 outbred mice with severe clinical outcomes following infection with Orientia tsutsugamushi. PLoS Negl Trop Dis 2022; 16:e0010459. [PMID: 36417363 PMCID: PMC9683618 DOI: 10.1371/journal.pntd.0010459] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2022] [Accepted: 10/28/2022] [Indexed: 11/24/2022] Open
Abstract
Orientia tsutsugamushi is an obligately intracellular bacterium with endothelial tropism and can cause mild to lethal scrub typhus in humans. No vaccine is available for this reemerging and severely neglected infection. Previous scrub typhus studies have utilized inbred mice, yet such models have intrinsic limitations. Thus, the development of suitable mouse models that better mimic human diseases is in great need for immunologic investigation and future vaccine studies. This study is aimed at establishing scrub typhus in outbred CD-1 mice and defining immune biomarkers related to disease severity. CD-1 mice received O. tsutsugamushi Karp strain via the i.v. route; major organs were harvested at 2-12 days post-infection for kinetic analyses. We found that for our given infection doses, CD-1 mice were significantly more susceptible (90-100% lethal) than were inbred C57BL/6 mice (0-10% lethal). Gross pathology of infected CD-1 mouse organs revealed features that mimicked human scrub typhus, including pulmonary edema, interstitial pneumonia, perivascular lymphocytic infiltrates, and vasculitis. Alteration in angiopoietin/receptor expression in inflamed lungs implied endothelial dysfunction. Lung immune gene profiling using NanoString analysis displayed a Th1/CD8-skewed, but Th2 repressed profile, including novel biomarkers not previously investigated in other scrub typhus models. Bio-plex analysis revealed a robust inflammatory response in CD-1 mice as evidenced by increased serum cytokine and chemokine levels, correlating with immune cell recruitment during the severe stages of the disease. This study provides an important framework indicating a value of CD-1 mice for delineating host susceptibility to O. tsutsugamushi, immune dysregulation, and disease pathogenesis. This preclinical model is particularly useful for future translational and vaccine studies for severe scrub typhus.
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Affiliation(s)
- Joseph Thiriot
- Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, Texas, United States of America
| | - Yuejin Liang
- Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, Texas, United States of America
- Institute for Human Infection and Immunity, University of Texas Medical Branch, Galveston, Texas, United States of America
| | - James Fisher
- Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, Texas, United States of America
| | - David H. Walker
- Department of Pathology, University of Texas Medical Branch, Galveston, Texas, United States of America
| | - Lynn Soong
- Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, Texas, United States of America
- Institute for Human Infection and Immunity, University of Texas Medical Branch, Galveston, Texas, United States of America
- Department of Pathology, University of Texas Medical Branch, Galveston, Texas, United States of America
- * E-mail:
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Panda S, Swain SK, Sahu BP, Sarangi R. Gene expression and involvement of signaling pathways during host-pathogen interplay in Orientia tsutsugamushi infection. 3 Biotech 2022; 12:180. [PMID: 35860421 PMCID: PMC9295102 DOI: 10.1007/s13205-022-03239-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2022] [Accepted: 06/18/2022] [Indexed: 11/22/2022] Open
Abstract
Scrub typhus is a neglected tropical disease that affects one-third of the world’s population. The disease is caused by Orientia tsutsugamushi (OT), an obligate intracellular Gram-negative bacterium. OT efficiently escapes from the endosomal pathway after entering the host cell and replicates inside cytosol. OT infection promotes cellular autophagy, the autonomous defense mechanism unlike other bacteria. This study has discussed the bacterial invasion process through the extracellular matrix and the immune response activated by the bacterium within the hosts. Furthermore, we have emphasized the importance of extracellular matrix and their cross-talk with the immune cells, such as, macrophages, neutrophils, and dendritic cells followed by their inflammatory response. We have also put an insight into the host factors associated with signaling pathways during scrub typhus disease with a special focus on the OT-induced stress response, autophagy, apoptosis, and innate immunity. Multiple cytokines and chemokines play a significant role in activating different immune-related signaling pathways. Due to the presence of high antigenic diversity among strains, the signaling pathways during the host–pathogen interplay of OT with its host is very complicated. Thus, it hinders to mitigate the severity of the pandemic occurred by the respective pathogen. Our investigation will provide a useful guide to better understand the virulence and physiology of this intracellular pathogen which will lead towards a better therapeutic diagnosis and vaccine development.
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Affiliation(s)
- Subhasmita Panda
- Department of Pediatrics, IMS and SUM Hospital, Siksha 'O' Anusandhan Deemed to be University, K8, Kalinga Nagar, Bhubaneswar, Odisha 751003 India
| | - Subrat Kumar Swain
- Centre for Genomics and Biomedical Informatics, IMS and SUM Hospital, Siksha 'O' Anusandhan Deemed to be University, K8, Kalinga Nagar, Bhubaneswar, Odisha 751003 India
| | - Basanta Pravas Sahu
- Discipline of Biosciences and Biomedical Engineering, Indian Institute of Technology Indore, Simrol, Indore 453552 India
| | - Rachita Sarangi
- Department of Pediatrics, IMS and SUM Hospital, Siksha 'O' Anusandhan Deemed to be University, K8, Kalinga Nagar, Bhubaneswar, Odisha 751003 India
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Mendell NL, Xu G, Shelite TR, Bouyer DH, Walker DH. A Murine Model of Waning Scrub Typhus Cross-Protection between Heterologous Strains of Orientia tsutsugamushi. Pathogens 2022; 11:pathogens11050512. [PMID: 35631033 PMCID: PMC9147814 DOI: 10.3390/pathogens11050512] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2022] [Revised: 04/08/2022] [Accepted: 04/21/2022] [Indexed: 02/01/2023] Open
Abstract
Orientia tsutsugamushi, the etiologic agent of the life-threatening febrile disease scrub typhus, is an obligately intracellular small coccobacillary bacterium belonging to the family Rickettsiaceae and is transmitted by the parasitic larval stage of trombiculid mites. Progress towards a vaccine for protection against scrub typhus has been impeded by characteristics of the pathogen and the infection. There are numerous strains of O. tsutsugamushi in the Asia-Pacific region with geographical overlap. In human cases immunity has been described as poor against heterologous strains of the pathogen, as well as short-lived against the homologous strain, with a mean antibody reversion rate of less than one year. Animal models of cross-protection as well as of deterioration of this cross-protection are needed to enhance understanding of transient immunity to scrub typhus. To build upon current understanding of this ineffective protection we sought to utilize our recently developed models, sublethal intradermal infection followed by challenge via ordinarily lethal hematogenous dissemination. Mice that were initially infected sublethally with O. tsutsugamushi Gilliam strain and were challenged with an ordinarily lethal dose of heterologous Karp strain were protected from death by a robust immune response at one month after the primary infection as evidenced by an abundance of mononuclear cellular infiltrates in target organs such as lung, liver, and kidney; maintenance of body weight; and low bacterial loads in the organs. Waning protection from lethal Karp strain challenge indicated by weight loss mirroring that observed in naïve mice was observed as early as 9 months after primary Gilliam strain infection, and higher bacterial loads, severe disease, and eventual death in some mice was observed after challenge with Karp strain at 14 months post-initial heterologous infection.
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Affiliation(s)
- Nicole L. Mendell
- Department of Pathology, University of Texas Medical Branch, Galveston, TX 77555, USA;
| | - Guang Xu
- College of Osteopathic Medicine, Marian University, Indianapolis, IN 46222, USA;
| | - Thomas R. Shelite
- Division of Infectious Diseases, Department of Internal Medicine, University of Texas Medical Branch, Galveston, TX 77555, USA;
| | - Donald H. Bouyer
- Department of Pathology, Center for Biodefense and Emerging Infectious Diseases, Center for Tropical Diseases, Sealy Institute for Vaccine Development, Institute of Human Infections and Immunity, University of Texas Medical Branch, Galveston, TX 77555, USA;
| | - David H. Walker
- Department of Pathology, Center for Biodefense and Emerging Infectious Diseases, Center for Tropical Diseases, Sealy Institute for Vaccine Development, Institute of Human Infections and Immunity, University of Texas Medical Branch, Galveston, TX 77555, USA;
- Correspondence: ; Tel.: +409-772-3990; Fax: +409-772-1850
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Comparison of Lethal and Nonlethal Mouse Models of Orientia tsutsugamushi Infection Reveals T-Cell Population-Associated Cytokine Signatures Correlated with Lethality and Protection. Trop Med Infect Dis 2021; 6:tropicalmed6030121. [PMID: 34287349 PMCID: PMC8293330 DOI: 10.3390/tropicalmed6030121] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2021] [Revised: 06/25/2021] [Accepted: 06/30/2021] [Indexed: 11/19/2022] Open
Abstract
The antigenic diversity of Orientia tsutsugamushi as well as the interstrain difference(s) associated with virulence in mice impose the necessity to dissect the host immune response. In this study we compared the host response in lethal and non-lethal murine models of O. tsutsugamushi infection using the two strains, Karp (New Guinea) and Woods (Australia). The models included the lethal model: Karp intraperitoneal (IP) challenge; and the nonlethal models: Karp intradermal (ID), Woods IP, and Woods ID challenges. We monitored bacterial trafficking to the liver, lung, spleen, kidney, heart, and blood, and seroconversion during the 21-day challenge. Bacterial trafficking to all organs was observed in both the lethal and nonlethal models of infection, with significant increases in average bacterial loads observed in the livers and hearts of the lethal model. Multicolor flow cytometry was utilized to analyze the CD4+ and CD8+ T cell populations and their intracellular production of the cytokines IFNγ, TNF, and IL2 (single, double, and triple combinations) associated with both the lethal and nonlethal murine models of infection. The lethal model was defined by a cytokine signature of double- (IFNγ-IL2) and triple-producing (IL2-TNF-IFNγ) CD4+ T-cell populations; no multifunctional signature was identified in the CD8+ T-cell populations associated with the lethal model. In the nonlethal model, the cytokine signature was predominated by CD4+ and CD8+ T-cell populations associated with single (IL2) and/or double (IL2-TNF) populations of producers. The cytokine signatures associated with our lethal model will become depletion targets in future experiments; those signatures associated with our nonlethal model are hypothesized to be related to the protective nature of the nonlethal challenges.
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Lu S, Zheng K, Wang J, Xu M, Xie Y, Yuan S, Wang C, Wu Y. Characterization of Treponema pallidum Dissemination in C57BL/6 Mice. Front Immunol 2021; 11:577129. [PMID: 33488577 PMCID: PMC7819853 DOI: 10.3389/fimmu.2020.577129] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2020] [Accepted: 11/20/2020] [Indexed: 11/13/2022] Open
Abstract
The spirochetal pathogen Treponema pallidum causes 5 million new cases of venereal syphilis worldwide each year. One major obstacle to syphilis prevention and treatment is the lack of suitable experimental animal models to study its pathogenesis. Accordingly, in this study, we further evaluated the responses of mice to Treponema pallidum. Quantitative polymerase chain reaction showed that Treponema pallidum could colonize the heart, liver, spleen, kidneys, and testicles of C57BL/6 mice, and the organism may be able to rapidly penetrate the blood-brain barrier in mice by 24 h after infection. In subsequent rabbit infectivity tests, we observed evident signs of the microorganism in the mouse lymph node suspension. After infection, bacterial loads were higher in the tissues than in the blood of C57BL/6 mice. Moreover, a significant Th1 immune response was recorded by cytokine assays. Flow cytometric analysis suggested an obvious increase in the proportion of CD3+ T and CD4+ T cells in the spleen cells in the infected mice. Thus, improving our understanding of the response of C57BL/6 mice for Treponema pallidum will help to comprehensive elucidate the pathogenic mechanisms of this bacterium and lay the foundation for the development of a new research model of Treponema pallidum.
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Affiliation(s)
- Simin Lu
- Hunan Province Cooperative Innovation Center for Molecular Target New Drug Study, Hengyang Medical College, Institution of Pathogenic Biology, University of South China, Hengyang, China
| | - Kang Zheng
- Hunan Province Cooperative Innovation Center for Molecular Target New Drug Study, Hengyang Medical College, Institution of Pathogenic Biology, University of South China, Hengyang, China
| | - Jianye Wang
- Hunan Province Cooperative Innovation Center for Molecular Target New Drug Study, Hengyang Medical College, Institution of Pathogenic Biology, University of South China, Hengyang, China
| | - Man Xu
- Hunan Province Cooperative Innovation Center for Molecular Target New Drug Study, Hengyang Medical College, Institution of Pathogenic Biology, University of South China, Hengyang, China
| | - Yafeng Xie
- Hunan Province Cooperative Innovation Center for Molecular Target New Drug Study, Hengyang Medical College, Institution of Pathogenic Biology, University of South China, Hengyang, China
- Clinical Laboratory, The Second Affiliated Hospital of University of South China, Hengyang, China
| | - Shuai Yuan
- Hunan Province Cooperative Innovation Center for Molecular Target New Drug Study, Hengyang Medical College, Institution of Pathogenic Biology, University of South China, Hengyang, China
| | - Chuan Wang
- Hunan Province Cooperative Innovation Center for Molecular Target New Drug Study, Hengyang Medical College, Institution of Pathogenic Biology, University of South China, Hengyang, China
| | - Yimou Wu
- Hunan Province Cooperative Innovation Center for Molecular Target New Drug Study, Hengyang Medical College, Institution of Pathogenic Biology, University of South China, Hengyang, China
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11
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Fisher J, Card G, Soong L. Neuroinflammation associated with scrub typhus and spotted fever group rickettsioses. PLoS Negl Trop Dis 2020; 14:e0008675. [PMID: 33091013 PMCID: PMC7580963 DOI: 10.1371/journal.pntd.0008675] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
Scrub typhus and spotted fever rickettsioses (SFR) are understudied, vector-borne diseases of global significance. Over 1 billion individuals are at risk for scrub typhus alone in an endemic region, spanning across eastern and southern Asia to Northern Australia. While highly treatable, diagnostic challenges make timely antibiotic intervention difficult for these diseases. Delayed therapy may lead to severe outcomes affecting multiple organs, including the central nervous system (CNS), where infection and associated neuroinflammation may be lethal or lead to lasting sequelae. Meningitis and encephalitis are prevalent in both scrub typhus and SFR. Additionally, case reports detailing focal neurological deficits have come to light, with attention to both acute and chronic sequelae of infection. Despite the increasing number of clinical reports outlining neurologic consequences of these diseases, relatively little research has examined underlying mechanisms of neuroinflammation. Animal models of scrub typhus have identified cerebral T-cell infiltration and vascular damage associated with endothelial infection and neuropathogenesis. Differential gene expression analysis of brain tissues during murine scrub typhus have revealed selective increases in CXCR3 ligands, proinflammatory and type-1 cytokines and chemokines, and cytotoxicity molecules, as well as alterations in the complement pathway. In SFR, microglial expansion and macrophage infiltration contribute to neurological disease progression. This narrative Review highlights clinical neurologic features of scrub typhus and SFR and evaluates our current understanding of basic research into neuroinflammation for both diseases in animal models. Further investigation into key mediators of neuropathogenesis may yield prognostic markers and treatment regimens for severe patients.
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Affiliation(s)
- James Fisher
- Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, Texas, United States of America
| | - Galen Card
- Department of Pathology, University of Texas Medical Branch, Galveston, Texas, United States of America
| | - Lynn Soong
- Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, Texas, United States of America
- Department of Pathology, University of Texas Medical Branch, Galveston, Texas, United States of America
- Institute for Human Infections and Immunity, University of Texas Medical Branch, Galveston, Texas, United States of America
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12
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Sarathy VV, Walker DH. Ideal Criteria for Accurate Mouse Models of Vector-Borne Diseases with Emphasis on Scrub Typhus and Dengue. Am J Trop Med Hyg 2020; 103:970-975. [PMID: 32602433 PMCID: PMC7470543 DOI: 10.4269/ajtmh.19-0955] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2019] [Accepted: 06/05/2020] [Indexed: 11/07/2022] Open
Abstract
Nine criteria regarding the infectious agent, mode of transmission, portal of entry, route of spread, target organs, target cells, pathologic lesions, incubation period, and modifiable spectrum of disease and outcomes appropriate to the intended experimental purpose are described. To provide context for each criterion, mouse models of two vector-borne zoonotic infectious diseases, scrub typhus and dengue, are summarized. Application of the criteria indicates that intravenous inoculation of Orientia tsutsugamushi into inbred mice is the best current model for life-threatening scrub typhus, and intradermal inoculation accurately models sublethal human scrub typhus, whereas the immunocompromised mouse models of dengue provide disease outcomes most closely associated with human dengue. In addition to addressing basic questions of immune and pathogenic mechanisms, mouse models are useful for preclinical testing of experimental vaccines and therapeutics. The nine criteria serve as guidelines to evaluate and compare models of vector-borne infectious diseases.
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Affiliation(s)
- Vanessa V. Sarathy
- Department of Pathology, Sealy Institute for Vaccine Sciences, Institute for Human Infections and Immunity, University of Texas Medical Branch, Galveston, Texas
| | - David H. Walker
- Department of Pathology, Sealy Institute for Vaccine Sciences, Institute for Human Infections and Immunity, University of Texas Medical Branch, Galveston, Texas
- Center for Biodefense and Emerging Infectious Diseases, University of Texas Medical Branch, Galveston, Texas
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13
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Long J, Wei Y, Tao X, He P, Xu J, Wu X, Zhu W, Chen K, Yang Z. Representative Genotyping, Recombination and Evolutionary Dynamics Analysis of TSA56 Gene Segment of Orientia tsutsugamushi. Front Cell Infect Microbiol 2020; 10:383. [PMID: 32903648 PMCID: PMC7438794 DOI: 10.3389/fcimb.2020.00383] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2020] [Accepted: 06/22/2020] [Indexed: 12/31/2022] Open
Abstract
Scrub typhus is a zoonotic disease caused by Orientia tsutsugamushi (O. tsutsugamushi). Orientia tsutsugamushi has various genotypes and more new strains with difference in sequences increasingly appeared. Whether the accurateness of one special nested PCR method which amplifies segment instead of entire open reading frame (ORF) sequence meets the current work of identifying new strains and classifying genotypes remains to be confirmed. And the origins and evolution of this organism have not been thoroughly elucidated. Accordingly, in this study, segments and the entire ORF of the 56-kDa type-specific antigen (TSA56) gene of O. tsutsugamushi were collected, including 209 clinically isolated strains in Guangzhou, China from 2012 to 2016 and 139 reference strains worldwide. By performing phylogenetic analysis, we proved that the accurateness of the particular PCR method which almost met detection need. This re-grouping result showed that segments perfectly represented and identified strains of Karp, Boryong, Gilliam, TA763, Kawasaki and part of Kato genotype, and this accuracy is not restricted by region and time. Sequence diversification of Shimokoshi and some Kato strains made their genotyping need to consider entire ORF sequences, but their weak recognition might not be due to recombination. The frequent genetic recombination and high point mutations contributed to genetic diversification of the TSA56 gene. Major overlapping regions of most recombination events occurred between strains of the same genotype, especially Karp and Kato genotype. And cross-genotype overlapping events occurred between Karp and Boryong/Gilliam/TA763/Kato, Kato and Kawasaki/Gilliam/TA686, Boryong and TA686, and Gilliam and Kawasaki. But Segment has quite low recombination frequency and stable mutation trend from 1943 to 2016. So segment is a relatively conserved part of the TSA56 ORF as for its stable trend of genetic diversity, and it may anchor and represent the entire TSA56 ORF gene. And genetic diversity is rejected as one potential reason for the increased incidence of scrub typhus. But an occasional recombination event created an unrecognized genotype which might be due to the breakage of VD II and AD II. Additionally, strains in Guangzhou were homologous and Karp genotype was detected as a dominant.
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Affiliation(s)
- Jiali Long
- Guangzhou Center for Disease Control and Prevention, Guangzhou, China
| | - Yuehong Wei
- Guangzhou Center for Disease Control and Prevention, Guangzhou, China
| | - Xia Tao
- Guangzhou Center for Disease Control and Prevention, Guangzhou, China
| | - Peng He
- Guangzhou Center for Disease Control and Prevention, Guangzhou, China
| | - Jianmin Xu
- Guangzhou Center for Disease Control and Prevention, Guangzhou, China
| | - Xinwei Wu
- Guangzhou Center for Disease Control and Prevention, Guangzhou, China
| | - Wei Zhu
- Guangzhou Center for Disease Control and Prevention, Guangzhou, China
| | - Kuncai Chen
- Guangzhou Center for Disease Control and Prevention, Guangzhou, China
| | - Zhicong Yang
- Guangzhou Center for Disease Control and Prevention, Guangzhou, China
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14
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Trent B, Liang Y, Xing Y, Esqueda M, Wei Y, Cho NH, Kim HI, Kim YS, Shelite TR, Cai J, Sun J, Bouyer DH, Liu J, Soong L. Polarized lung inflammation and Tie2/angiopoietin-mediated endothelial dysfunction during severe Orientia tsutsugamushi infection. PLoS Negl Trop Dis 2020; 14:e0007675. [PMID: 32119672 PMCID: PMC7067486 DOI: 10.1371/journal.pntd.0007675] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2019] [Revised: 03/12/2020] [Accepted: 01/29/2020] [Indexed: 12/17/2022] Open
Abstract
Orientia tsutsugamushi infection can cause acute lung injury and high mortality in humans; however, the underlying mechanisms are unclear. Here, we tested a hypothesis that dysregulated pulmonary inflammation and Tie2-mediated endothelial malfunction contribute to lung damage. Using a murine model of lethal O. tsutsugamushi infection, we demonstrated pathological characteristics of vascular activation and tissue damage: 1) a significant increase of ICAM-1 and angiopoietin-2 (Ang2) proteins in inflamed tissues and lung-derived endothelial cells (EC), 2) a progressive loss of endothelial quiescent and junction proteins (Ang1, VE-cadherin/CD144, occuludin), and 3) a profound impairment of Tie2 receptor at the transcriptional and functional levels. In vitro infection of primary human EC cultures and serum Ang2 proteins in scrub typhus patients support our animal studies, implying endothelial dysfunction in severe scrub typhus. Flow cytometric analyses of lung-recovered cells further revealed that pulmonary macrophages (MΦ) were polarized toward an M1-like phenotype (CD80+CD64+CD11b+Ly6G-) during the onset of disease and prior to host death, which correlated with the significant loss of CD31+CD45- ECs and M2-like (CD206+CD64+CD11b+Ly6G-) cells. In vitro studies indicated extensive bacterial replication in M2-type, but not M1-type, MΦs, implying the protective and pathogenic roles of M1-skewed responses. This is the first detailed investigation of lung cellular immune responses during acute O. tsutsugamushi infection. It uncovers specific biomarkers for vascular dysfunction and M1-skewed inflammatory responses, highlighting future therapeutic research for the control of this neglected tropical disease.
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Affiliation(s)
- Brandon Trent
- Department of Pathology, University of Texas Medical Branch, Galveston, Texas, United States of America
| | - Yuejin Liang
- Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, Texas, United States of America
| | - Yan Xing
- Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, Texas, United States of America
| | - Marisol Esqueda
- Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, Texas, United States of America
| | - Yang Wei
- Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, Texas, United States of America
| | - Nam-Hyuk Cho
- Department of Microbiology and Immunology, Seoul National University College of Medicine, Seoul Republic of Korea
- Department of Biomedical Sciences, Seoul National University College of Medicine, Seoul, Republic of Korea
| | - Hong-Il Kim
- Department of Biomedical Sciences, Seoul National University College of Medicine, Seoul, Republic of Korea
| | - Yeon-Sook Kim
- Division of Infectious Diseases, Department of Internal Medicine, Chungnam National University School of Medicine, Daejeon, Republic of Korea
| | - Thomas R. Shelite
- Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, Texas, United States of America
| | - Jiyang Cai
- Department of Ophthalmology & Visual Sciences, University of Texas Medical Branch, Galveston, Galveston, Texas, United States of America
| | - Jiaren Sun
- Department of Pathology, University of Texas Medical Branch, Galveston, Texas, United States of America
- Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, Texas, United States of America
| | - Donald H. Bouyer
- Department of Pathology, University of Texas Medical Branch, Galveston, Texas, United States of America
| | - Jinjun Liu
- Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Xi’an Jiaotong University Health Science Center, Xi’an, China
| | - Lynn Soong
- Department of Pathology, University of Texas Medical Branch, Galveston, Texas, United States of America
- Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, Texas, United States of America
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15
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Kim HI, Ha NY, Kim G, Min CK, Kim Y, Yen NTH, Choi MS, Cho NH. Immunization with a recombinant antigen composed of conserved blocks from TSA56 provides broad genotype protection against scrub typhus. Emerg Microbes Infect 2019; 8:946-958. [PMID: 31237478 PMCID: PMC6598529 DOI: 10.1080/22221751.2019.1632676] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Scrub typhus is an acute febrile disease caused by Orientia tsutsugamushi infection. Despite the wide range of approaches explored during the last seventy years, an effective prophylactic vaccine is not yet available. Here, we developed a novel recombinant antigen derived from conserved regions of 56 kDa type-specific antigen (TSA56), a major outer membrane protein responsible for genetic heterogeneity and antigenicity, and evaluated it as a protective vaccine antigen. Our findings demonstrate that immunization with conserved blocks of TSA56 (cTSA56) not only provides protective immunity against lethal challenges with the homologous genotype, but also confers significantly better protection against heterologous genotypes than TSA56. Adoptive transfer of CD4+ or CD8+ T cells from immunized mice provided significantly enhanced protection against lethal challenge, whereas immune B cells failed to do so, indicating that cellular immunity against the conserved epitopes plays a protective role. Moreover, immunization with a 10-mer peptide mixture, screened from CD8+ T cell epitopes within the conserved region of TSA56, provided enhanced protection against lethal challenge with O. tsutsugamushi. Therefore, this novel recombinant antigen is a promising candidate for scrub typhus vaccine against a wide range of O. tsutsugamushi genotypes.
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Affiliation(s)
- Hong-Il Kim
- a Department of Microbiology and Immunology , Seoul National University College of Medicine , Seoul , Republic of Korea.,b Department of Biomedical Sciences , Seoul National University College of Medicine , Seoul , Republic of Korea
| | - Na-Young Ha
- a Department of Microbiology and Immunology , Seoul National University College of Medicine , Seoul , Republic of Korea.,b Department of Biomedical Sciences , Seoul National University College of Medicine , Seoul , Republic of Korea
| | - Gwanghun Kim
- a Department of Microbiology and Immunology , Seoul National University College of Medicine , Seoul , Republic of Korea.,b Department of Biomedical Sciences , Seoul National University College of Medicine , Seoul , Republic of Korea
| | - Chan-Ki Min
- a Department of Microbiology and Immunology , Seoul National University College of Medicine , Seoul , Republic of Korea.,b Department of Biomedical Sciences , Seoul National University College of Medicine , Seoul , Republic of Korea
| | - Yuri Kim
- a Department of Microbiology and Immunology , Seoul National University College of Medicine , Seoul , Republic of Korea.,b Department of Biomedical Sciences , Seoul National University College of Medicine , Seoul , Republic of Korea
| | - Nguyen Thi Hai Yen
- a Department of Microbiology and Immunology , Seoul National University College of Medicine , Seoul , Republic of Korea.,b Department of Biomedical Sciences , Seoul National University College of Medicine , Seoul , Republic of Korea
| | - Myung-Sik Choi
- a Department of Microbiology and Immunology , Seoul National University College of Medicine , Seoul , Republic of Korea
| | - Nam-Hyuk Cho
- a Department of Microbiology and Immunology , Seoul National University College of Medicine , Seoul , Republic of Korea.,b Department of Biomedical Sciences , Seoul National University College of Medicine , Seoul , Republic of Korea.,c Institute of Endemic Disease, Seoul National University Medical Research Center and Bundang Hospital , Seoul , Republic of Korea
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16
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Trent B, Fisher J, Soong L. Scrub Typhus Pathogenesis: Innate Immune Response and Lung Injury During Orientia tsutsugamushi Infection. Front Microbiol 2019; 10:2065. [PMID: 31555249 PMCID: PMC6742975 DOI: 10.3389/fmicb.2019.02065] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2019] [Accepted: 08/22/2019] [Indexed: 01/28/2023] Open
Abstract
Scrub typhus is an understudied, potentially lethal disease caused by infection with Orientia tsutsugamushi. Despite causing an estimated 1 million cases per year and an increasing global presence, mechanisms of scrub typhus pathogenesis remain unclear. One of the most life-threatening conditions that can arise in scrub typhus patients is acute respiratory distress syndrome (ARDS). The development of ARDS is a complex process; some of its pathological hallmarks, including prolonged recruitment of inflammatory immune cells to the lung and vasculature damage, have been observed in humans and/or animal models of O. tsutsugamushi infection. Although different cell types and mechanisms may contribute to ARDS development during O. tsutsugamushi infection, this review highlights our current evidence of pulmonary endothelial activation and damage, the potential roles of neutrophils and macrophages in the lung, and the knowledge gaps in this field. Continued investigation of the lung microenvironment and cellular interactions will help elucidate disease pathogenesis and possible treatment during scrub typhus.
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Affiliation(s)
- Brandon Trent
- Department of Pathology, University of Texas Medical Branch, Galveston, TX, United States
| | - James Fisher
- Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, TX, United States
| | - Lynn Soong
- Department of Pathology, University of Texas Medical Branch, Galveston, TX, United States.,Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, TX, United States
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Londoño AF, Mendell NL, Walker DH, Bouyer DH. A biosafety level-2 dose-dependent lethal mouse model of spotted fever rickettsiosis: Rickettsia parkeri Atlantic Rainforest strain. PLoS Negl Trop Dis 2019; 13:e0007054. [PMID: 31216274 PMCID: PMC6602283 DOI: 10.1371/journal.pntd.0007054] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2018] [Revised: 07/01/2019] [Accepted: 05/21/2019] [Indexed: 11/28/2022] Open
Abstract
Background The species of the Rickettsia genus are separated into four groups: the ancestral group, typhus group, transitional group and spotted fever group. Rickettsia parkeri, a spotted fever group Rickettsia, has been reported across the American continents as infecting several tick species and is associated with a relatively mild human disease characterized by eschar formation at the tick feeding site, regional lymphadenopathy, fever, myalgia and rash. Currently, there are several mouse models that provide good approaches to study the acute lethal disease caused by Rickettsia, but these models can only be performed in an animal biosafety level 3 laboratory. We present an alternative mouse model for acute lethal rickettsial disease, using R. parkeri Atlantic Rainforest strain and C3H/HeN mice, with the advantage that this model can be studied in an animal biosafety level 2 laboratory. Principal findings In the C3H/HeN mouse model, we determined that infection with 1x106 and 1x107 viable R. parkeri Atlantic Rainforest strain organisms produced dose-dependent severity, whereas infection with 1x108 viable bacteria resulted in a lethal illness. The animals became moribund on day five or six post-infection. The lethal disease was characterized by ruffled fur, erythema, labored breathing, decreased activity, and hunched posture, which began on day three post-infection (p.i.) and coincided with the peak bacterial loads. Significant splenomegaly (on days three and five p.i.), neutrophilia (on days three and five p.i.), and thrombocytopenia (on days one, three and five p.i.) were observed. Significance Since R. parkeri is used at biosafety level 2, the greatest advantage of this inbred mouse model is the ability to investigate immunity and pathogenesis of rickettsiosis with all the tools available at biosafety level 2. Rickettsia is a bacterial genus that contains distinct species that are transmitted by arthropods. Many of these agents produce infection and disease in humans. The illness can range from very severe, such as Rocky Mountain spotted fever caused by Rickettsia rickettsii to mild human disease characterized by eschar formation at the tick feeding site and less severe symptoms caused by Rickettsia parkeri and often apparently asymptomatic seroconversion as observed with R. amblyommatis. To study these diseases, animal models are invaluable, and mouse models offer the best advantages for studies of immunity and pathogenesis because of the availability of immunologic reagents and gene knockout animals. Several mouse models are available for the study of the acute lethal disease produced by these bacteria, providing the opportunity to test different treatments and vaccine candidates. However, work with these models requires an animal biosafety level 3 laboratory. In this report, we present an alternative mouse model with R. parkeri Atlantic Rainforest strain available for investigation in a biosafety level 2 laboratory to study an acute dose-dependent lethal spotted fever group rickettsial disease with the advantage that experiments can be performed at this biosafety level.
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Affiliation(s)
- Andrés F. Londoño
- Department of Pathology, The University of Texas Medical Branch, Galveston, Texas, United States of America
- Research Group on Veterinary Sciences “Centauro”, Facultad de Ciencias Agrarias, Universidad de Antioquia, Medellín, Antioquia, Colombia
- * E-mail:
| | - Nicole L. Mendell
- Department of Pathology, The University of Texas Medical Branch, Galveston, Texas, United States of America
| | - David H. Walker
- Department of Pathology, The University of Texas Medical Branch, Galveston, Texas, United States of America
| | - Donald H. Bouyer
- Department of Pathology, The University of Texas Medical Branch, Galveston, Texas, United States of America
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18
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Díaz FE, Abarca K, Kalergis AM. An Update on Host-Pathogen Interplay and Modulation of Immune Responses during Orientia tsutsugamushi Infection. Clin Microbiol Rev 2018; 31:e00076-17. [PMID: 29386235 PMCID: PMC5967693 DOI: 10.1128/cmr.00076-17] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
The obligate intracellular bacterium Orientia tsutsugamushi is the causative agent of scrub typhus in humans, a serious mite-borne disease present in a widespread area of endemicity, which affects an estimated 1 million people every year. This disease may exhibit a broad range of presentations, ranging from asymptomatic to fatal conditions, with the latter being due to disseminated endothelial infection and organ injury. Unique characteristics of the biology and host-pathogen interactions of O. tsutsugamushi, including the high antigenic diversity among strains and the highly variable, short-lived memory responses developed by the host, underlie difficulties faced in the pursuit of an effective vaccine, which is an imperative need. Other factors that have hindered scientific progress relative to the infectious mechanisms of and the immune response triggered by this bacterium in vertebrate hosts include the limited number of mechanistic studies performed on animal models and the lack of genetic tools currently available for this pathogen. However, recent advances in animal model development are promising to improve our understanding of host-pathogen interactions. Here, we comprehensively discuss the recent advances in and future perspectives on host-pathogen interactions and the modulation of immune responses related to this reemerging disease, highlighting the role of animal models.
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Affiliation(s)
- Fabián E Díaz
- Millennium Institute on Immunology and Immunotherapy, Departamento de Genética Molecular y Microbiología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Katia Abarca
- Departamento en Enfermedades Infecciosas e Inmunología Pediátricas, Facultad de Medicina, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Alexis M Kalergis
- Millennium Institute on Immunology and Immunotherapy, Departamento de Genética Molecular y Microbiología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile
- Departamento de Endocrinología, Facultad de Medicina, Pontificia Universidad Católica de Chile, Santiago, Chile
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19
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Xu G, Mendell NL, Liang Y, Shelite TR, Goez-Rivillas Y, Soong L, Bouyer DH, Walker DH. CD8+ T cells provide immune protection against murine disseminated endotheliotropic Orientia tsutsugamushi infection. PLoS Negl Trop Dis 2017; 11:e0005763. [PMID: 28723951 PMCID: PMC5536391 DOI: 10.1371/journal.pntd.0005763] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2017] [Revised: 07/31/2017] [Accepted: 06/30/2017] [Indexed: 12/19/2022] Open
Abstract
Scrub typhus, caused by a Gram-negative obligately intracellular coccobacillus, Orientia tsutsugamushi, is a long neglected but important tropical disease. Orientia tsutsugamushi causes illness in one million people each year, and 1 billion people are at risk. Without appropriate diagnosis and treatment, the disease can cause severe multiorgan failure with a case fatality rate of 7–15%. The current gaps in knowledge of immunity include the unknown mechanisms of host immunity to O. tsutsugamushi. Using an intravenous (i.v.) disseminated infection mouse model, we observed that more CD8+ T cells than CD4+ T cells were present in the spleen of infected mice at 12 dpi. We also determined that Treg cells and the proportion of T cells producing IL-10 were significantly increased from 6 dpi, which correlated with the onset of illness, body weight loss, and increased bacterial loads. We further studied CD8-/-, MHC I-/- and wild type control (WT) C57BL/6J mice to determine the importance of CD8+ T cells and MHC I molecules. After infection with an ordinarily sub-lethal dose of O. tsutsugamushi, all CD8-/- and MHC I-/- mice were moribund between 12 and 15 dpi, whereas all WT mice survived. Bacterial loads in the lung, kidney, liver and spleen of CD8-/- and MHC I-/- mice were significantly greater than those in WT mice. Interferon-γ (IFN-γ) and granzyme B mRNA levels in the liver of CD8-/- and MHC I-/- mice were significantly greater than in WT mice. In addition, more severe histopathologic lesions were observed in CD8-/- mice. Finally, adoptive transfer confirmed a major role of immune CD8+ T cells as well as a less effective contribution by immune CD8 T cell-depleted splenocytes in protection against O. tsutsugamushi infection. These studies demonstrated the critical importance of CD8+ T cells in the host immune response during O. tsutsugamushi infection. Scrub typhus is a febrile illness that can be life-threatening without appropriate treatment. It is caused by a gram-negative, obligately intracellular bacterium, Orientia tsutsugamushi. Approximately one million people annually are infected globally, mainly in the Asia-Pacific area. Unfortunately, no vaccine has been developed for the prevention of the disease. There is very little known about the pathogenesis of or host immunity to scrub typhus. The limited number of studies on the mechanisms of immunity has failed to provide a fundamental explanation of the protective host immune response during the disease due in part to the outdated and inaccurate animal models employed. Here, we examined and confirmed that CD8+ T cells provide critical protection during the infection. Our data also demonstrated the potential contribution of non-CD8+ immune cells in protection against the infection. This study of host immune responses during scrub typhus with a more accurate mouse model improves the understanding of the interaction between the host and pathogen, and provides a foundation for future investigations of pathogenesis, immune control and prevention including vaccine development.
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Affiliation(s)
- Guang Xu
- Department of Pathology, The University of Texas Medical Branch, Galveston, Texas, United States of America
| | - Nicole L Mendell
- Department of Pathology, The University of Texas Medical Branch, Galveston, Texas, United States of America
| | - Yuejin Liang
- Department of Microbiology and Immunology, The University of Texas Medical Branch, Galveston, Texas, United States of America
| | - Thomas R Shelite
- Department of Internal Medicine, Division of Infectious Diseases, The University of Texas Medical Branch, Galveston, Texas, United States of America
| | - Yenny Goez-Rivillas
- Department of Pathology, The University of Texas Medical Branch, Galveston, Texas, United States of America
| | - Lynn Soong
- Department of Pathology, The University of Texas Medical Branch, Galveston, Texas, United States of America.,Department of Microbiology and Immunology, The University of Texas Medical Branch, Galveston, Texas, United States of America
| | - Donald H Bouyer
- Department of Pathology, The University of Texas Medical Branch, Galveston, Texas, United States of America
| | - David H Walker
- Department of Pathology, The University of Texas Medical Branch, Galveston, Texas, United States of America.,Department of Microbiology and Immunology, The University of Texas Medical Branch, Galveston, Texas, United States of America
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