1
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A rough Brucella mutant induced macrophage death depends on secretion activity of T4SS, but not on cellular Txnip- and Caspase-2-mediated signaling pathway. Vet Microbiol 2020; 244:108648. [PMID: 32402333 DOI: 10.1016/j.vetmic.2020.108648] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2019] [Revised: 03/03/2020] [Accepted: 03/17/2020] [Indexed: 12/30/2022]
Abstract
Brucella is a facultative intracellular bacterium, dividing into smooth- and rough-type Brucella. Smooth-type Brucella can dissociate into rough mutants with cytotoxicity for macrophages during infection, which is critical for Brucella egress and dissemination. However, the mechanism of cytotoxicity infected by rough Brucella is incomplete. In this study, we verified that a rough-type Brucella (RB14 strain) was cytotoxic for macrophages dependent on Type IV secretion system (T4SS). Two specific T4SS VirB4 and VirB11 mutants were constructed, which affect the secretion of T4SS effectors, but not the expression of T4SS components. Cytotoxicity analysis showed that RB14- induced macrophages death depends on T4SS secretion activity. In a further study, 15 reported T4SS effectors were evaluated in inducing macrophage death using over-expression and transfection methods, the results showed that 15 recombinant strains with over-expression of respective effector were not cytotoxicity. In addition, 10 effectors transfected individually, or co-transfected with five effectors barely induced macrophage death, suggesting that all 15 effectors were not associated with macrophage death. Besides, we also evaluated endoplasmic reticulum (ER) stress, Txnip- or Caspase-2 roles in RB14-induced macrophages death. The results showed that inhibition of ER stress, Caspase or Caspase-2 activation was not associated with RB14-infected macrophages death. The casp2 and txnip knockout cells also showed death when infected by the RB14 strain. In all, the RB14-induced macrophage death depends on the secretion activity of T4SS, but not on ER stress, Txnip- or Caspase-2 signal pathway. This study provides a deep insight for rough Brucella-induced macrophage death, which favors for elucidating Brucella infection lifecycle.
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2
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Zhi F, Zhou D, Bai F, Li J, Xiang C, Zhang G, Jin Y, Wang A. VceC Mediated IRE1 Pathway and Inhibited CHOP-induced Apoptosis to Support Brucella Replication in Goat Trophoblast Cells. Int J Mol Sci 2019; 20:ijms20174104. [PMID: 31443507 PMCID: PMC6747397 DOI: 10.3390/ijms20174104] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2019] [Revised: 08/17/2019] [Accepted: 08/20/2019] [Indexed: 02/03/2023] Open
Abstract
The effectors of the type IV secretion system (T4SS) of bacteria play important roles in mediating bacterial intracellular proliferation and manipulating host-related pathway responses to bacterial infection. Brucella Spp. inhibit the apoptosis of host cells to benefit their own intracellular proliferation. However, the underlying mechanisms between T4SS effectors and Brucella-inhibited apoptosis in goat trophoblast cells remain unclear. Here, based on Brucella suis vaccine strain 2, the VceC was deleted by allelic exchange. We show that ΔVceC was able to infect and proliferate to high titers in goat trophoblast cells (GTCs) and increase C/EBP-homologous protein (CHOP)-mediated apoptosis. GRP78 expression decreased upon ΔVceC infection. In addition, we discovered that the inositolrequiring enzyme 1 (IRE1) pathway was inhibited in this process. Changing endoplasmic reticulum (ER) stress affected Brucella intracellular replication in GTCs. The replication of ΔVceC was more sensitive under the different ERstress conditions in the GTC line after treatment with ER stress inhibitors 4 phenyl butyric acid (4-PBA) or ER stress activator Tm. Together, our findings show that VceC has a protective effect on the intracellular persistence of Brucella infection, and inhibits ER stress-induced apoptosis in the CHOP pathway. The present work provides new insights for understanding the mechanism of VceC in the establishment of chronic Brucella infection.
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Affiliation(s)
- Feijie Zhi
- Key Laboratory of Animal Biotechnology of the Ministry of Agriculture, Northwest A&F University, Yangling 712100, China
| | - Dong Zhou
- Key Laboratory of Animal Biotechnology of the Ministry of Agriculture, Northwest A&F University, Yangling 712100, China
- College of Veterinary Medicine, Northwest A&F University, Yangling 712100, China
| | - Furong Bai
- Key Laboratory of Animal Biotechnology of the Ministry of Agriculture, Northwest A&F University, Yangling 712100, China
| | - Junmei Li
- Key Laboratory of Animal Biotechnology of the Ministry of Agriculture, Northwest A&F University, Yangling 712100, China
| | - Caixia Xiang
- Key Laboratory of Animal Biotechnology of the Ministry of Agriculture, Northwest A&F University, Yangling 712100, China
| | - Guangdong Zhang
- Key Laboratory of Animal Biotechnology of the Ministry of Agriculture, Northwest A&F University, Yangling 712100, China
| | - Yaping Jin
- Key Laboratory of Animal Biotechnology of the Ministry of Agriculture, Northwest A&F University, Yangling 712100, China
- College of Veterinary Medicine, Northwest A&F University, Yangling 712100, China
| | - Aihua Wang
- Key Laboratory of Animal Biotechnology of the Ministry of Agriculture, Northwest A&F University, Yangling 712100, China.
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3
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Wang Y, Ke Y, Duan C, Ma X, Hao Q, Song L, Guo X, Sun T, Zhang W, Zhang J, Zhao Y, Zhong Z, Yang X, Chen Z. A small non-coding RNA facilitates Brucella melitensis intracellular survival by regulating the expression of virulence factor. Int J Med Microbiol 2019; 309:225-231. [PMID: 31054808 DOI: 10.1016/j.ijmm.2019.04.002] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2018] [Revised: 03/10/2019] [Accepted: 04/18/2019] [Indexed: 12/19/2022] Open
Abstract
Brucella species are the causative agents of brucellosis, a worldwide zoonotic disease that affects a broad range of mammals and causes great economic losses. Small regulatory RNAs (sRNAs) are post-transcriptional regulatory molecules that participate in the stress adaptation and pathogenesis of Brucella. In this study, we characterized the role of a novel sRNA, BSR1141, in the intracellular survival and virulence of Brucella melitensis. The results show that BSR1141 was highly induced during host infections and under in vitro stress situations that simulated the conditions encountered within host phagocytes. In addition, a BSR1141 mutant showed reduced survival both under in vitro stress conditions and in mice, confirming the role of BSR1141 in Brucella intracellular survival. Bioinformatic and experimental approaches revealed that BSR1141 affects the expression of many target genes, including the Brucella virulence component virB2. These data indicate that BSR1141 could influence the expression of virB2, which is important for B. melitensis pathogenesis and intracellular survival. This work provides new insight into the mechanism of adaptation to environmental stress and into the pathogenesis of intracellular pathogens.
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Affiliation(s)
- Yufei Wang
- Department of laboratory medicine, The Third Medical Center, General Hospital of the Chinese People's Liberation Army, Beijing 100039, China
| | - Yuehua Ke
- Department of Infectious Disease Control, Center of Disease Control and Prevention, Beijing 100071, China
| | - Cuijuan Duan
- Department of laboratory medicine, The Third Medical Center, General Hospital of the Chinese People's Liberation Army, Beijing 100039, China
| | - Xueping Ma
- Department of laboratory medicine, The Third Medical Center, General Hospital of the Chinese People's Liberation Army, Beijing 100039, China
| | - Qinfang Hao
- Department of laboratory medicine, The Third Medical Center, General Hospital of the Chinese People's Liberation Army, Beijing 100039, China
| | - Lijie Song
- Department of laboratory medicine, The Third Medical Center, General Hospital of the Chinese People's Liberation Army, Beijing 100039, China
| | - Xiaojin Guo
- Department of laboratory medicine, The Third Medical Center, General Hospital of the Chinese People's Liberation Army, Beijing 100039, China
| | - Tao Sun
- Department of laboratory medicine, The Third Medical Center, General Hospital of the Chinese People's Liberation Army, Beijing 100039, China
| | - Wei Zhang
- Department of laboratory medicine, The Third Medical Center, General Hospital of the Chinese People's Liberation Army, Beijing 100039, China
| | - Jing Zhang
- Department of laboratory medicine, The Third Medical Center, General Hospital of the Chinese People's Liberation Army, Beijing 100039, China
| | - Yiwen Zhao
- Department of laboratory medicine, The Third Medical Center, General Hospital of the Chinese People's Liberation Army, Beijing 100039, China
| | - Zhijun Zhong
- Key Laboratory of Animal Disease and Human Health of Sichuan Province, College of Veterinary Medicine, Sichuan Agricultural University, Sichuan 611130, China.
| | - Xiaoli Yang
- Department of laboratory medicine, The Third Medical Center, General Hospital of the Chinese People's Liberation Army, Beijing 100039, China.
| | - Zeliang Chen
- Department of Infectious Disease Control, Center of Disease Control and Prevention, Beijing 100071, China; Key Laboratory of Livestock Infectious Diseases in Northeast China, Ministry of Education, Key Laboratory of Zoonosis of Liaoning Province, College of Aninal Science and Veterinary Medicine, Shenyang Agricultural University, Liaoning, 110866, China.
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4
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Li P, Tian M, Hu H, Yin Y, Guan X, Ding C, Wang S, Yu S. Lable-free based comparative proteomic analysis of secretory proteins of rough Brucella mutants. J Proteomics 2019; 195:66-75. [PMID: 30659936 DOI: 10.1016/j.jprot.2019.01.008] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2018] [Revised: 01/07/2019] [Accepted: 01/13/2019] [Indexed: 01/18/2023]
Abstract
Brucella rough mutants are reported to induce infected macrophage death, which is type IV secretion system (T4SS) dependent. T4SS and its secretory proteins play a major role in host-bacteria interactions, but the crucial secretory proteins to promote macrophage death during Brucella rough mutant infection have not been characterized. In this study, we found that T4SS components played no role for macrophage death induced by Brucella rough mutant infection, but some T4SS effectors did. Proteomics of secretory proteins from Brucella rough mutants ΔrfbE and ΔrfbEΔvirB123 was analyzed by liquid chromatography/tandem mass spectrometry and 861 unique proteins were identified, among which 37 were differential secretory proteins. Gene ontology and pathway analysis showed that differential secretory proteins involved in cellular process and metabolic process, distributed in the cell and membrane, possessed molecular function of catalytic activity and binding, and were associated with ribosome, NOD-like receptor signaling pathway, two-component system and bacterial secretion system. Cell death analysis showed that T4SS effector VceC, and two differential secretory proteins OmpW family protein (BAB1_1579) and protein BAB1_1185 were associated with Brucella cytotoxicity. This study provides new insights into the molecular mechanisms associated with Brucella cytotoxicity and valuable information for screening vaccine candidates for Brucella. SIGNIFICANCE: Brucella rough mutants induce infected macrophage death, which is T4SS dependent. In the present report, a comparative proteomics analysis revealed 37 differential secretory proteins between Brucella rough mutants ΔrfbE and ΔrfbEΔvirB123. Further study demonstrated OmpW family protein (BAB1_1579) and uncharacterized protein BAB1_1185, two differential secretory proteins, were associated with Brucella cytotoxicity. This study provides novel information of the secretory proteins from the Brucella rough mutants and their effects on the Brucella cytotoxicity.
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Affiliation(s)
- Peng Li
- Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Sciences (CAAS), Shanghai 200241, PR China
| | - Mingxing Tian
- Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Sciences (CAAS), Shanghai 200241, PR China
| | - Hai Hu
- Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Sciences (CAAS), Shanghai 200241, PR China
| | - Yi Yin
- Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Sciences (CAAS), Shanghai 200241, PR China
| | - Xiang Guan
- Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Sciences (CAAS), Shanghai 200241, PR China
| | - Chan Ding
- Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Sciences (CAAS), Shanghai 200241, PR China
| | - Shaohui Wang
- Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Sciences (CAAS), Shanghai 200241, PR China
| | - Shengqing Yu
- Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Sciences (CAAS), Shanghai 200241, PR China; Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonosis, Yangzhou, PR China.
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5
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Li ZQ, Zhang JL, Xi L, Yang GL, Wang SL, Zhang XG, Zhang JB, Zhang H. Deletion of the transcriptional regulator GntR down regulated the expression of Genes Related to Virulence and Conferred Protection against Wild-Type Brucella Challenge in BALB/c Mice. Mol Immunol 2017; 92:99-105. [PMID: 29055858 DOI: 10.1016/j.molimm.2017.10.011] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2017] [Revised: 09/29/2017] [Accepted: 10/15/2017] [Indexed: 01/03/2023]
Abstract
Brucellosis, which is caused by Brucella spp., is a zoonotic infectious disease that can cause great hazard to public health and safety. The virulence of Brucella is essential for survive and multiply in host macrophages. GntR is a transcriptional regulator in Brucella that is required for virulence in macrophages and mice, and involved in resistance to stress responses. To determine the expression levels of target genes of GntR, we detected the expression levels of the GntR target genes in Brucella infected BALB/c mice. The results showed that several genes related to virulence, including omp25, virB1, vjbR, dnaK, htrA and hfq, were regulated by GntR during infection in BALB/c mice. Moreover, the 2308ΔgntR mutant induced high protective immunity in BALB/c mice challenge with B. abortus 2308 (S2308), and elicited an anti-Brucella-specific immunoglobulin G (IgG) response and induced the secretion of gamma interferon (IFN-γ) and interleukin-4 (IL-4). All together, these results indicated that gntR promoted the virulence of Brucella. The 2308ΔgntR was significantly attenuated in macrophages and mice and induced protective immune response during infection, suggested that 2308ΔgntR mutant is an attractive candidate for the design of a live attenuated vaccine against Brucella.
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Affiliation(s)
- Zhi-Qiang Li
- School of Biotechnology and Food, Shangqiu Normal University, Shangqiu 476000, Henan Province, China
| | - Jin-Liang Zhang
- School of Biotechnology and Food, Shangqiu Normal University, Shangqiu 476000, Henan Province, China
| | - Li Xi
- School of Biotechnology and Food, Shangqiu Normal University, Shangqiu 476000, Henan Province, China
| | - Guang-Li Yang
- School of Biotechnology and Food, Shangqiu Normal University, Shangqiu 476000, Henan Province, China
| | - Shu-Li Wang
- School of Biotechnology and Food, Shangqiu Normal University, Shangqiu 476000, Henan Province, China
| | - Xiao-Gen Zhang
- School of Biotechnology and Food, Shangqiu Normal University, Shangqiu 476000, Henan Province, China
| | - Jun-Bo Zhang
- College of Biology, Agriculture and Forestry, Tongren University, Tongren 554300, Guizhou Province, China
| | - Hui Zhang
- College of Animal Science and Technology, Shihezi University, Shihezi 832003, Xinjiang Province, China.
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6
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Li P, Tian M, Bao Y, Hu H, Liu J, Yin Y, Ding C, Wang S, Yu S. Brucella Rough Mutant Induce Macrophage Death via Activating IRE1α Pathway of Endoplasmic Reticulum Stress by Enhanced T4SS Secretion. Front Cell Infect Microbiol 2017; 7:422. [PMID: 29021973 PMCID: PMC5623715 DOI: 10.3389/fcimb.2017.00422] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2017] [Accepted: 09/14/2017] [Indexed: 11/21/2022] Open
Abstract
Brucella is a Gram-negative facultative intracellular pathogen that causes the worldwide zoonosis, known as brucellosis. Brucella virulence relies mostly on its ability to invade and replicate within phagocytic cells. The type IV secretion system (T4SS) and lipopolysaccharide are two major Brucella virulence factors. Brucella rough mutants reportedly induce the death of infected macrophages, which is T4SS dependent. However, the underlying molecular mechanism remains unclear. In this study, the T4SS secretion capacities of Brucella rough mutant and its smooth wild-type strain were comparatively investigated, by constructing the firefly luciferase fused T4SS effector, BPE123 and VceC. In addition, quantitative real-time PCR and western blotting were used to analyze the T4SS expression. The results showed that T4SS expression and secretion were enhanced significantly in the Brucella rough mutant. We also found that the activity of the T4SS virB operon promoter was notably increased in the Brucella rough mutant, which depends on quorum sensing-related regulators of VjbR upregulation. Cell infection and cell death assays revealed that deletion of vjbR in the Brucella rough mutant absolutely abolished cytotoxicity within macrophages by downregulating T4SS expression. This suggests that up-regulation of T4SS promoted by VjbR in rough mutant ΔrfbE contribute to macrophage death. In addition, we found that the Brucella rough mutant induce macrophage death via activating IRE1α pathway of endoplasmic reticulum stress. Taken together, our study provide evidence that in comparison to the Brucella smooth wild-type strain, VjbR upregulation in the Brucella rough mutant increases transcription of the virB operon, resulting in overexpression of the T4SS gene, accompanied by the over-secretion of effecter proteins, thereby causing the death of infected macrophages via activating IRE1α pathway of endoplasmic reticulum stress, suggesting novel insights into the molecular mechanisms associated with Brucella rough mutant-induced macrophage cytotoxicity.
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Affiliation(s)
- Peng Li
- Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Shanghai, China
| | - Mingxing Tian
- Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Shanghai, China
| | - Yanqing Bao
- Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Shanghai, China
| | - Hai Hu
- Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Shanghai, China
| | - Jiameng Liu
- Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Shanghai, China
| | - Yi Yin
- Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Shanghai, China
| | - Chan Ding
- Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Shanghai, China
| | - Shaohui Wang
- Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Shanghai, China
| | - Shengqing Yu
- Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Shanghai, China.,Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonosis, Yangzhou, China
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7
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Transcriptional regulator GntR of Brucella abortus regulates cytotoxicity, induces the secretion of inflammatory cytokines and affects expression of the type IV secretion system and quorum sensing system in macrophages. World J Microbiol Biotechnol 2017; 33:60. [DOI: 10.1007/s11274-017-2230-9] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2016] [Accepted: 02/16/2017] [Indexed: 11/26/2022]
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8
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Li ZQ, Gui D, Sun ZH, Zhang JB, Zhang WZ, Zhang H, Guo F, Chen CF. Immunization of BALB/c mice with Brucella abortus 2308ΔwbkA confers protection against wild-type infection. J Vet Sci 2016; 16:467-73. [PMID: 26040616 PMCID: PMC4701739 DOI: 10.4142/jvs.2015.16.4.467] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2014] [Revised: 03/26/2015] [Accepted: 04/04/2015] [Indexed: 12/16/2022] Open
Abstract
Brucellosis is a zoonotic disease that causes animal and human diseases. Vaccination is a major measure for prevention of brucellosis, but it is currently not possible to distinguish vaccinated animals from those that have been naturally infected. Therefore, in this study, we constructed the Brucella (B.) abortus 2380 wbkA mutant (2308ΔwbkA) and evaluated its virulence. The survival of 2308ΔwbkA was attenuated in murine macrophage (RAW 264.7) and BALB/c mice, and it induced high protective immunity in mice. The wbkA mutant elicited an anti-Brucella-specific immunoglobulin G response and induced the secretion of gamma interferon. Antibodies to 2308ΔwbkA could be detected in sera from mice, implying the potential for use of this protein as a diagnostic antigen. The WbkA antigen would allow serological differentiation between infected and vaccinated animals. These results suggest that 2308ΔwbkA is a potential attenuated vaccine against 16M. This vaccine will be further evaluated in sheep.
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Affiliation(s)
- Zhi-qiang Li
- College of Animal Science and Technology, Shihezi University, Shihezi 832000, China.,School of life sciences, Shangqiu normal university, Shangqiu 476000, China
| | - Dan Gui
- College of Animal Science and Technology, Shihezi University, Shihezi 832000, China
| | - Zhi-hua Sun
- College of Animal Science and Technology, Shihezi University, Shihezi 832000, China
| | - Jun-bo Zhang
- College of Biology, Agriculture and Forestry, Tongren University, Tongren 554300, China
| | - Wen-zhi Zhang
- College of Animal Science and Technology, Shihezi University, Shihezi 832000, China
| | - Hui Zhang
- College of Animal Science and Technology, Shihezi University, Shihezi 832000, China.,College of Co-Innovation Center for Zoonotic Infectious Diseases in the Western Region, Shihezi University, Shihezi 832000, China
| | - Fei Guo
- College of Biology, Agriculture and Forestry, Tongren University, Tongren 554300, China.,College of Medicine, Shihezi University, Shihezi 832000, China
| | - Chuang-fu Chen
- College of Animal Science and Technology, Shihezi University, Shihezi 832000, China.,College of Co-Innovation Center for Zoonotic Infectious Diseases in the Western Region, Shihezi University, Shihezi 832000, China
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9
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Brucella TIR-like protein TcpB/Btp1 specifically targets the host adaptor protein MAL/TIRAP to promote infection. Biochem Biophys Res Commun 2016; 477:509-14. [PMID: 27311859 DOI: 10.1016/j.bbrc.2016.06.064] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2016] [Accepted: 06/13/2016] [Indexed: 02/06/2023]
Abstract
Brucella spp. are known to avoid host immune recognition and weaken the immune response to infection. Brucella like accomplish this by employing two clever strategies, called the stealth strategy and hijacking strategy. The TIR domain-containing protein (TcpB/Btp1) of Brucella melitensis is thought to be involved in inhibiting host NF-κB activation by binding to adaptors downstream of Toll-like receptors. However, of the five TIR domain-containing adaptors conserved in mammals, whether MyD88 or MAL, even other three adaptors, are specifically targeted by TcpB has not been identified. Here, we confirmed the effect of TcpB on B.melitensis virulence in mice and found that TcpB selectively targets MAL. By using siRNA against MAL, we found that TcpB from B.melitensis is involved in intracellular survival and that MAL affects intracellular replication of B.melitensis. Our results confirm that TcpB specifically targets MAL/TIRAP to disrupt downstream signaling pathways and promote intra-host survival of Brucella spp.
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10
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Li Z, Fu Q, Wang Z, Li T, Zhang H, Guo F, Wang Y, Zhang J, Chen C. TceSR two-component regulatory system of Brucella melitensis 16M is involved in invasion, intracellular survival and regulated cytotoxicity for macrophages. Lett Appl Microbiol 2015; 60:565-71. [PMID: 25721466 DOI: 10.1111/lam.12408] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2014] [Revised: 01/21/2015] [Accepted: 02/17/2015] [Indexed: 11/29/2022]
Abstract
The mechanisms of invasion and intracellular survival of Brucella are still poorly understood. Previous studies showed that the two-component regulatory systems (TCSs) play an important role in the intracellular survival of Brucella. To investigate if TCSs involve in the virulence and cytotoxicity of Brucella melitensis, we introduced a mutation into one of the TCSs in chromosome II in Br. melitensis 16M strain, and generated 16MΔTceSR, a mutant of Br. melitensis 16M strain. In vitro infection experiments using murine macrophage cell line (RAW 264.7) showed that the survival of 16MΔTceSR mutant in macrophages decreased 0·91-log compared with that of wild type Br. melitensis 16M strain at 2 h postinfection, replication of 16MΔTceSR mutant in macrophages was 5·65-log, which was much lower than that wild type strain. Results of lactate dehydrogenase cytotoxicity assays in macrophages demonstrated high dose infection with wide type strain produced high level cytotoxicity to macrophages, but 16MΔTceSR mutant had very low level cytotoxicity, indicating mutation of TCSs impaired the cytotoxicity of Br. melitensis to macrophages. Animal experiments showed that the spleen colonization of 16MΔTceSR was significantly reduced compared with its wild type strains. The lower levels of survival of 16MΔTceSR in various stress conditions suggested that the mutation of the TCSs of Br. melitensis was the causative factor of its reduced resistance to stress conditions. Taken together, our results demonstrated TCS TceSR involves in the intracellular survival, virulence and cytotoxicity of Br. melitensis during its infection. Significance and impact of the study: Two-component systems (TCSs) are predominant bacterial signal transduction mechanisms. The pathogenicity of Brucella is due to its ability to adapt to the intracellular environment including low levels of acidic pH, high-salt and heat shock. TCSs are designed to sense diverse stimuli, transfer signals and enact an appropriate adaptive physiological response. Here, we show that Br. meilitensis TCS TceSR is not only involved in regulation of Br. meilitensis virulence and adaptation of environmental stresses, but also can regulate cytotoxicity in macrophages.
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Affiliation(s)
- Z Li
- College of Animal Science and Technology/Co-Innovation Center for Zoonotic Infectious Diseases in the western region, Shihezi University, Shihezi, China
| | - Q Fu
- College of Animal Science and Technology/Co-Innovation Center for Zoonotic Infectious Diseases in the western region, Shihezi University, Shihezi, China
| | - Z Wang
- College of Animal Science and Technology/Co-Innovation Center for Zoonotic Infectious Diseases in the western region, Shihezi University, Shihezi, China
| | - T Li
- College of Animal Science and Technology/Co-Innovation Center for Zoonotic Infectious Diseases in the western region, Shihezi University, Shihezi, China
| | - H Zhang
- College of Animal Science and Technology/Co-Innovation Center for Zoonotic Infectious Diseases in the western region, Shihezi University, Shihezi, China
| | - F Guo
- College of Medicine, Shihezi University, Shihezi, China
| | - Y Wang
- College of Medicine, Shihezi University, Shihezi, China
| | - J Zhang
- College of Biology, Agriculture and Forestry, Tongren University, Tongren, Guizhou, China
| | - C Chen
- College of Animal Science and Technology/Co-Innovation Center for Zoonotic Infectious Diseases in the western region, Shihezi University, Shihezi, China
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11
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Silva TMA, Mol JPS, Winter MG, Atluri V, Xavier MN, Pires SF, Paixão TA, Andrade HM, Santos RL, Tsolis RM. The predicted ABC transporter AbcEDCBA is required for type IV secretion system expression and lysosomal evasion by Brucella ovis. PLoS One 2014; 9:e114532. [PMID: 25474545 PMCID: PMC4256435 DOI: 10.1371/journal.pone.0114532] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2014] [Accepted: 11/10/2014] [Indexed: 12/23/2022] Open
Abstract
Brucella ovis is a major cause of reproductive failure in rams and it is one of the few well-described Brucella species that is not zoonotic. Previous work showed that a B. ovis mutant lacking a species-specific ABC transporter (ΔabcBA) was attenuated in mice and was unable to survive in macrophages. The aim of this study was to evaluate the role of this ABC transporter during intracellular survival of B. ovis. In HeLa cells, B. ovis WT was able to survive and replicate at later time point (48 hpi), whereas an ΔabcBA mutant was attenuated at 24 hpi. The reduced survival of the ΔabcBA mutant was associated with a decreased ability to exclude the lysosomal marker LAMP1 from its vacuolar membrane, suggesting a failure to establish a replicative niche. The ΔabcBA mutant showed a reduced abundance of the Type IV secretion system (T4SS) proteins VirB8 and VirB11 in both rich and acid media, when compared to WT B. ovis. However, mRNA levels of virB1, virB8, hutC, and vjbR were similar in both strains. These results support the notion that the ABC transporter encoded by abcEDCBA or its transported substrate acts at a post-transcriptional level to promote the optimal expression of the B. ovis T4SS within infected host cells.
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Affiliation(s)
- Teane M. A. Silva
- Departamento de Clínica e Cirurgia Veterinária, Escola de Veterinária da Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil
| | - Juliana P. S. Mol
- Departamento de Clínica e Cirurgia Veterinária, Escola de Veterinária da Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil
| | - Maria G. Winter
- Department of Medical Microbiology and Immunology, University of California Davis, Davis, California, United States of America
| | - Vidya Atluri
- Department of Medical Microbiology and Immunology, University of California Davis, Davis, California, United States of America
| | - Mariana N. Xavier
- Department of Medical Microbiology and Immunology, University of California Davis, Davis, California, United States of America
| | - Simone F. Pires
- Departamento de Parasitologia, Instituto de Ciências Biológicas da Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil
| | - Tatiane A. Paixão
- Departamento de Patologia Geral, Instituto de Ciências Biológicas da Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil
| | - Hélida M. Andrade
- Departamento de Parasitologia, Instituto de Ciências Biológicas da Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil
| | - Renato L. Santos
- Departamento de Clínica e Cirurgia Veterinária, Escola de Veterinária da Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil
- * E-mail: (RLS); (RMT)
| | - Renee M. Tsolis
- Department of Medical Microbiology and Immunology, University of California Davis, Davis, California, United States of America
- * E-mail: (RLS); (RMT)
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Lee JJ, Lim JJ, Kim DG, Simborio HL, Kim DH, Reyes AWB, Min W, Lee HJ, Kim DH, Chang HH, Kim S. Characterization of culture supernatant proteins from Brucella abortus and its protection effects against murine brucellosis. Comp Immunol Microbiol Infect Dis 2014; 37:221-8. [PMID: 25016407 DOI: 10.1016/j.cimid.2014.06.001] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2014] [Revised: 05/13/2014] [Accepted: 06/05/2014] [Indexed: 01/18/2023]
Abstract
In this study, we characterized the secreted proteins of Brucella abortus into the enriched media under the bacterial laboratory growth condition and investigated the pathogenic importance of culture supernatant (CS) proteins to B. abortus infection. CS proteins from stationary phase were concentrated and analyzed using 2D electrophoresis. In MALDI TOF/TOF analysis, more than 27 proteins including CuZn SOD, Dps, Tat, OMPs, Adh, LivF, Tuf, SucC, GroEL and DnaK were identified. Cytotoxic effects of CS proteins were found to increase in a dose-dependent manner in RAW 264.7 cells. Upon B. abortus challenge into phagocytes, however, CS proteins pre-treated cells exhibited lower bacterial uptake and intracellular replication compared to untreated cells. Immunization with CS proteins induced a strong humoral and cell mediated immune responses and exhibited significant higher degree of protection against virulence of B. abortus infection compared to mice immunized with Brucella broth protein (BBP). Taken together, these results indicate that B. abortus secreted a number of soluble immunogenic proteins under laboratory culture condition, which can promote antibody production resulted in enhancing host defense against to subsequently bacterial infection. Moreover, further analysis of CS proteins may help to understand the pathogenic mechanism of B. abortus infection and host-pathogen interaction.
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Affiliation(s)
- Jin Ju Lee
- Animal and Plant Quarantine Agency, Anyang, Gyeonggi-do 430-757, Republic of Korea; College of Veterinary Medicine, Gyeongsang National University, Jinju 660-701, Republic of Korea
| | - Jeong Ju Lim
- College of Veterinary Medicine, Gyeongsang National University, Jinju 660-701, Republic of Korea
| | - Dae Geun Kim
- College of Veterinary Medicine, Gyeongsang National University, Jinju 660-701, Republic of Korea
| | - Hannah Leah Simborio
- College of Veterinary Medicine, Gyeongsang National University, Jinju 660-701, Republic of Korea
| | - Dong Hyeok Kim
- College of Veterinary Medicine, Gyeongsang National University, Jinju 660-701, Republic of Korea
| | | | - WonGi Min
- College of Veterinary Medicine, Gyeongsang National University, Jinju 660-701, Republic of Korea
| | - Hu Jang Lee
- College of Veterinary Medicine, Gyeongsang National University, Jinju 660-701, Republic of Korea
| | - Dong Hee Kim
- School of Medicine, Gyeongsang National University, Jinju 660-701, Republic of Korea
| | - Hong Hee Chang
- Institute of Agriculture and Life Science, Gyeongsang National University, Jinju 660-701, Republic of Korea
| | - Suk Kim
- College of Veterinary Medicine, Gyeongsang National University, Jinju 660-701, Republic of Korea; Institute of Agriculture and Life Science, Gyeongsang National University, Jinju 660-701, Republic of Korea.
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13
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Mechanism of Asp24 upregulation in Brucella abortus rough mutant with a disrupted O-antigen export system and effect of Asp24 in bacterial intracellular survival. Infect Immun 2014; 82:2840-50. [PMID: 24752516 DOI: 10.1128/iai.01765-14] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
We previously showed that Brucella abortus rough mutant strain 2308 ΔATP (called the ΔrfbE mutant in this study) exhibits reduced intracellular survival in RAW264.7 cells and attenuated persistence in BALB/c mice. In this study, we performed microarray analysis to detect genes with differential expression between the ΔrfbE mutant and wild-type strain S2308. Interestingly, acid shock protein 24 gene (asp24) expression was significantly upregulated in the ΔrfbE mutant compared to S2308, as confirmed by quantitative reverse transcription-PCR (qRT-PCR) and Western blotting. Further studies using additional strains indicated that the upregulation of asp24 occurred only in rough mutants with disrupted O-antigen export system components, including the ATP-binding protein gene rfbE (bab1_0542) and the permease gene rfbD (bab1_0543), while the ΔwboA rough mutant (which lacks an O-antigen synthesis-related glycosyltransferase) and the RB51 strain (a vaccine strain with the rough phenotype) showed no significant changes in asp24 expression compared to S2308. In addition, abolishing the intracellular O-antigen synthesis of the ΔrfbE mutant by deleting the wboA gene (thereby creating the ΔrfbE ΔwboA double-knockout strain) recovered asp24 expression. These results indicated that asp24 upregulation is associated with intracellular O-antigen synthesis and accumulation but not with the bacterial rough phenotype. Further studies indicated that asp24 upregulation in the ΔrfbE mutant was associated neither with bacterial adherence and invasion nor with cellular necrosis on RAW264.7 macrophages. However, proper expression of the asp24 gene favors intracellular survival of Brucella in RAW264.7 cells and HeLa cells during an infection. This study reveals a novel mechanism for asp24 upregulation in B. abortus mutants.
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Pei J, Kahl-McDonagh M, Ficht TA. Brucella dissociation is essential for macrophage egress and bacterial dissemination. Front Cell Infect Microbiol 2014; 4:23. [PMID: 24634889 PMCID: PMC3942807 DOI: 10.3389/fcimb.2014.00023] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2013] [Accepted: 02/10/2014] [Indexed: 12/24/2022] Open
Abstract
It has long been observed that smooth Brucella can dissociate into rough mutants that are cytotoxic to macrophages. However, the in vivo biological significance and/or mechanistic details of Brucella dissociation and cytotoxicity remain incomplete. In the current report, a plaque assay was developed using Brucella strains exhibiting varying degrees of cytotoxicity. Infected monolayers were observed daily using phase contrast microscopy for plaque formation while Brucella uptake and replication were monitored using an immunofluorescence assay (IFA). Visible plaques were detected at 4-5 days post infection (p.i.) with cytotoxic Brucella 16MΔmanBA at an MOI of 0.1. IFA staining demonstrated that the plaques consisted of macrophages with replicating Brucella. Visible plaques were not detected in monolayers infected with non-cytotoxic 16MΔmanBAΔvirB2 at an MOI of 0.1. However, IFA staining did reveal small groups of macrophages (foci) with replicating Brucella in the monolayers infected with 16MΔmanBAΔvirB2. The size of the foci observed in macrophage monolayers infected with rough Brucella correlated directly with cytotoxicity measured in liquid culture, suggesting that cytotoxicity was essential for Brucella egress and dissemination. In monolayers infected with 16M, small and large foci were observed. Double antibody staining revealed spontaneous rough mutants within the large, but not the small foci in 16M infected monolayers. Furthermore, plaque formation was observed in the large foci derived from 16M infections. Finally, the addition of gentamicin to the culture medium inhibited plaque formation, suggesting that cell-to-cell spread occurred only following release of the organisms from the cells. Taken together, these results demonstrate that Brucella-induced cytotoxicity is critical for Brucella egress and dissemination.
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Affiliation(s)
| | | | - Thomas A. Ficht
- Department of Veterinary Pathobiology, Texas A&M University and Texas Agricultural Experiment StationCollege Station, TX, USA
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Sá JC, Silva TMA, Costa EA, Silva APC, Tsolis RM, Paixão TA, Carvalho Neta AV, Santos RL. The virB-encoded type IV secretion system is critical for establishment of infection and persistence of Brucella ovis infection in mice. Vet Microbiol 2012; 159:130-40. [PMID: 22483850 DOI: 10.1016/j.vetmic.2012.03.029] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2012] [Revised: 03/08/2012] [Accepted: 03/10/2012] [Indexed: 12/13/2022]
Abstract
Brucella spp. are gram-negative intracellular bacterial pathogens that cause chronic infections. Brucella virulence factors include a type IV secretion system (T4SS) and its lipopolysaccharide (LPS), which are essential for persistence. However, the role of the virB-encoded T4SS has not been investigated in naturally rough Brucella species such as Brucella ovis. In this study, male 6-week old BALBc mice were infected with B. ovis, Brucella abortus, and their respective ΔvirB2 mutant strains. During early infection, B. ovis and B. abortus wild type strains were similarly recovered from spleen. Interestingly, in contrast to ΔvirB2 B. abortus that was recovered at similar levels when compared to the wild type strain, the ΔvirB2 B. ovis was markedly attenuated as early as 24h post infection (hpi). The ΔvirB2 B. ovis was unable to survive and multiply in murine peritoneal macrophages and extracellularly within the peritoneal cavity at 12 and 24 hpi with lower splenic colonization than the parental strain at 6, 12 and 24 hpi. In contrast, wild type B. abortus and ΔvirB2 B. abortus had a similar kinetics of infection in this model. As expected, the T4SS was essential for intracellular replication of smooth and rough strains in RAW macrophages at 48 hpi. These results suggest that T4SS is important for survival of B. ovis in murine model, and that a T4SS deficient B. ovis strain is cleared at earlier stages of infection when compared to a similar B. abortus mutant.
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Affiliation(s)
- Joicy C Sá
- Departamento de Clínica e Cirurgia Veterinária, Escola de Veterinária, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brazil
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16
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von Bargen K, Gorvel JP, Salcedo SP. Internal affairs: investigating the Brucella intracellular lifestyle. FEMS Microbiol Rev 2012; 36:533-62. [PMID: 22373010 DOI: 10.1111/j.1574-6976.2012.00334.x] [Citation(s) in RCA: 153] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2011] [Revised: 01/10/2012] [Accepted: 02/16/2012] [Indexed: 01/18/2023] Open
Abstract
Bacteria of the genus Brucella are Gram-negative pathogens of several animal species that cause a zoonotic disease in humans known as brucellosis or Malta fever. Within their hosts, brucellae reside within different cell types where they establish a replicative niche and remain protected from the immune response. The aim of this article is to discuss recent advances in the field in the specific context of the Brucella intracellular 'lifestyle'. We initially discuss the different host cell targets and their relevance during infection. As it represents the key to intracellular replication, the focus is then set on the maturation of the Brucella phagosome, with particular emphasis on the Brucella factors that are directly implicated in intracellular trafficking and modulation of host cell signalling pathways. Recent data on the role of the type IV secretion system are discussed, novel effector molecules identified and how some of them impact on trafficking events. Current knowledge on Brucella gene regulation and control of host cell death are summarized, as they directly affect intracellular persistence. Understanding how Brucella molecules interplay with their host cell targets to modulate cellular functions and establish the intracellular niche will help unravel how this pathogen causes disease.
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Affiliation(s)
- Kristine von Bargen
- Faculté de Sciences de Luminy, Centre d'Immunologie de Marseille-Luminy, Aix Marseille Université, UM 2, Marseille Cedex, France
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Wang Y, Bai Y, Qu Q, Xu J, Chen Y, Zhong Z, Qiu Y, Wang T, Du X, Wang Z, Yu S, Fu S, Yuan J, Zhen Q, Yu Y, Chen Z, Huang L. The 16MΔvjbR as an ideal live attenuated vaccine candidate for differentiation between Brucella vaccination and infection. Vet Microbiol 2011; 151:354-62. [PMID: 21530111 DOI: 10.1016/j.vetmic.2011.03.031] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2010] [Revised: 03/22/2011] [Accepted: 03/28/2011] [Indexed: 11/19/2022]
Abstract
Brucellosis brings great economic burdens for developing countries. Live attenuated vaccines are the most efficient means for prevention and control of animal Brucellosis. However, the difficulties of differentiating of infection from vaccine immunization, which is essential for eradication programs, limit their applications. Therefore, the development of a vaccine that could differentiate infection from immunization will overcome the limitations and get extensive application. VjbR is a quorum sensing regulator involving in Brucella's intracellular survival. The vjbR∷Tn5 mutants have been proven effective against wild type strain challenge, implying its possibility of use in vaccine candidate development. To further evaluate this candidate gene, in the present study, the antigenicity of purified recombinant VjbR protein was analyzed. Antibodies to Brucella melitensis VjbR could be detected in sera from patients and animals with brucellosis but not in control ones, implying the potential use of this protein as a diagnostic antigen. Then a vjbR mutant of B. melitensis 16M was constructed by replacing the vjbR with kanamycin gene. The mutant showed reduced survival in macrophage and mice. Vaccination of BALB/c mice with 16MΔvjbR conferred significant protective immunity against B. melitensis strain 16M challenges, being equivalent to which induced by the license vaccine Rev.1. The vjbR deletion mutant elicited an anti-Brucella-specific immunoglobulin G response and induced the secretion of gamma interferon and interleukin-10. The most importance is that, the use of vjbR mutants as vaccines in association with diagnostic tests based on the VjbR antigen would allow the serological differentiation between infected and vaccinated animals. These results suggest that 16MΔvjbR is an ideal live attenuated vaccine candidate against B. melitensis and deserves further evaluation for vaccine development.
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Affiliation(s)
- Yufei Wang
- Department of Infectious Disease, Institute of Disease Control and Prevention, Academy of Military Medical Science, Beijing 100071, PR China
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Proinflammatory caspase-2-mediated macrophage cell death induced by a rough attenuated Brucella suis strain. Infect Immun 2011; 79:2460-9. [PMID: 21464087 DOI: 10.1128/iai.00050-11] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Brucella spp. are intracellular bacteria that cause an infectious disease called brucellosis in humans and many domestic and wildlife animals. B. suis primarily infects pigs and is pathogenic to humans. The macrophage-Brucella interaction is critical for the establishment of a chronic Brucella infection. Our studies showed that smooth virulent B. suis strain 1330 (S1330) prevented programmed cell death of infected macrophages and rough attenuated B. suis strain VTRS1 (a vaccine candidate) induced strong macrophage cell death. To further investigate the mechanism of VTRS1-induced macrophage cell death, microarrays were used to analyze temporal transcriptional responses of murine macrophage-like J774.A1 cells infected with S1330 or VTRS1. In total 17,685 probe sets were significantly regulated based on the effects of strain, time and their interactions. A miniTUBA dynamic Bayesian network analysis predicted that VTRS1-induced macrophage cell death was mediated by a proinflammatory gene (the tumor necrosis factor alpha [TNF-α] gene), an NF-κB pathway gene (the IκB-α gene), the caspase-2 gene, and several other genes. VTRS1 induced significantly higher levels of transcription of 40 proinflammatory genes than S1330. A Mann-Whitney U test confirmed the proinflammatory response in VTRS1-infected macrophages. Increased production of TNF-α and interleukin 1β (IL-1β) were also detected in the supernatants in VTRS1-infected macrophage cell culture. Hyperphosphorylation of IκB-α was observed in macrophages infected with VTRS1 but not S1330. The important roles of TNF-α and IκB-α in VTRS1-induced macrophage cell death were further confirmed by individual inhibition studies. VTRS1-induced macrophage cell death was significantly inhibited by a caspase-2 inhibitor but not a caspase-1 inhibitor. The role of caspase-2 in regulating the programmed cell death of VTRS1-infected macrophages was confirmed in another study using caspase-2-knockout mice. In summary, VTRS1 induces a proinflammatory, caspase-2- and NF-κB-mediated macrophage cell death. This unique cell death differs from apoptosis, which is not proinflammatory. It is also different from classical pyroptosis, which is caspase-1 mediated.
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Lowry JE, Isaak DD, Leonhardt JA, Vernati G, Pate JC, Andrews GP. Vaccination with Brucella abortus recombinant in vivo-induced antigens reduces bacterial load and promotes clearance in a mouse model for infection. PLoS One 2011; 6:e17425. [PMID: 21412420 PMCID: PMC3055878 DOI: 10.1371/journal.pone.0017425] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2010] [Accepted: 02/04/2011] [Indexed: 01/18/2023] Open
Abstract
Current vaccines used for the prevention of brucellosis are ineffective in inducing protective immunity in animals that are chronically infected with Brucella abortus, such as elk. Using a gene discovery approach, in vivo-induced antigen technology (IVIAT) on B. abortus, we previously identified ten loci that encode products up-regulated during infection in elk and consequently may play a role in virulence. In our present study, five of the loci (D15, 0187, VirJ, Mdh, AfuA) were selected for further characterization and compared with three additional antigens with virulence potential (Hia, PrpA, MltA). All eight genes were PCR-amplified from B. abortus and cloned into E. coli. The recombinant products were then expressed, purified, adjuvanted, and delivered subcutaneously to BALB/c mice. After primary immunization and two boosts, mice were challenged i.p. with 5 x 10⁴ CFU of B. abortus strain 19. Spleens from challenged animals were harvested and bacterial loads determined by colony count at various time points. While vaccination with four of the eight individual proteins appeared to have some effect on clearance kinetics, mice vaccinated with recombinant Mdh displayed the most significant reduction in bacterial colonization. Furthermore, mice immunized with Mdh maintained higher levels of IFN-γ in spleens compared to other treatment groups. Collectively, our in vivo data gathered from the S19 murine colonization model suggest that vaccination with at least three of the IVIAT antigens conferred an enhanced ability of the host to respond to infection, reinforcing the utility of this methodology for the identification of potential vaccine candidates against brucellosis. Mechanisms for immunity to one protein, Mdh, require further in vitro exploration and evaluation against wild-type B. abortus challenge in mice, as well as other hosts. Additional studies are being undertaken to clarify the role of Mdh and other IVI antigens in B. abortus virulence and induction of protective immunity.
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Affiliation(s)
- Jake E Lowry
- Department of Veterinary Sciences, University of Wyoming, Laramie, Wyoming, United States of America.
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Wang Y, Chen Z, Qiao F, Zhong Z, Xu J, Wang Z, Du X, Qu Q, Yuan J, Jia L, Song H, Sun Y, Huang L. The type IV secretion system affects the expression of Omp25/Omp31 and the outer membrane properties ofBrucella melitensis. FEMS Microbiol Lett 2010; 303:92-100. [DOI: 10.1111/j.1574-6968.2009.01866.x] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
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