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Kim S, Son B, Kim H, Shin H, Ryu S. Precision Phage Cocktail Targeting Surface Appendages for Biocontrol of Salmonella in Cold-Stored Foods. Antibiotics (Basel) 2024; 13:799. [PMID: 39334974 PMCID: PMC11428620 DOI: 10.3390/antibiotics13090799] [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: 07/22/2024] [Revised: 08/22/2024] [Accepted: 08/22/2024] [Indexed: 09/30/2024] Open
Abstract
Salmonella enterica is a major food-borne pathogen causing food poisoning. The use of bacteriophages as alternative biocontrol agents has gained renewed interest due to the rising issue of antibiotic-resistant bacteria. We isolated and characterized three phages targeting Salmonella: SPN3US, SPN3UB, and SPN10H. Morphological and genomic analyses revealed that they belong to the class Caudoviricetes. SPN3UB, SPN3US, and SPN10H specifically target bacterial surface molecules as receptors, including O-antigens of lipopolysaccharides, flagella, and BtuB, respectively. The phages exhibited a broad host range against Salmonella strains, highlighting their potential for use in a phage cocktail. Bacterial challenge assays demonstrated significant lytic activity of the phage cocktail consisting of the three phages against S. typhimurium UK1, effectively delaying the emergence of phage-resistant bacteria. The phage cocktail effectively reduced Salmonella contamination in foods, including milk and pork and chicken meats, during cold storage. These results indicate that a phage cocktail targeting different host receptors could serve as a promising antimicrobial strategy to control Salmonella.
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Affiliation(s)
- Seongok Kim
- Department of Food Science & Biotechnology, College of Life Science, Sejong University, Seoul 05006, Republic of Korea;
- Carbohydrate Bioproduct Research Center, College of Life Science, Sejong University, Seoul 05006, Republic of Korea
| | - Bokyung Son
- Department of Food Biotechnology, Dong-A University, Busan 49315, Republic of Korea;
| | - Hyeryen Kim
- Department of Food and Animal Biotechnology, Research Institute of Agriculture and Life Sciences, Seoul National University, Seoul 08826, Republic of Korea;
- Department of Agricultural Biotechnology, Seoul National University, Seoul 08826, Republic of Korea
| | - Hakdong Shin
- Department of Food Science & Biotechnology, College of Life Science, Sejong University, Seoul 05006, Republic of Korea;
- Carbohydrate Bioproduct Research Center, College of Life Science, Sejong University, Seoul 05006, Republic of Korea
| | - Sangryeol Ryu
- Department of Food and Animal Biotechnology, Research Institute of Agriculture and Life Sciences, Seoul National University, Seoul 08826, Republic of Korea;
- Department of Agricultural Biotechnology, Seoul National University, Seoul 08826, Republic of Korea
- Center for Food and Bioconvergence, Seoul National University, Seoul 08826, Republic of Korea
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Tian Y, Huang S, Zhou G, Fei X, Li YA, Li Q, Wang S, Shi H. Evaluation of immunogenicity and protective efficacy of outer membrane vesicles from Salmonella Typhimurium and Salmonella Choleraesuis. Vet Microbiol 2024; 294:110131. [PMID: 38805917 DOI: 10.1016/j.vetmic.2024.110131] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2023] [Revised: 05/18/2024] [Accepted: 05/23/2024] [Indexed: 05/30/2024]
Abstract
Outer membrane vesicles (OMVs) are membranous structures frequently observed in Gram-negative bacteria that contain bioactive substances. These vesicles are rich in bacterial antigens that can activate the host's immune system, making them a promising candidate vaccine to prevent and manage bacterial infections. The aim of this study was to assess the immunogenicity and protective efficacy of OMVs derived from Salmonella enterica serovar Typhimurium and S. Choleraesuis, while also focusing on enhancing OMV production. Initial experiments showed that OMVs from wild-type strains did not provide complete protection against homologous Salmonella challenge, possible due to the presence of flagella in the purified OMVs samples, which may elicit an unnecessary immune response. To address this, flagellin-deficient mutants of S. Typhimurium and S. Choleraesuis were constructed, designated rSC0196 and rSC0199, respectively. These mutants exhibited reduced cell motility and their OMVs were found to be flagellin-free. Immunization with non-flagellin OMVs derived from rSC0196 induced robust antibody responses and improved survival rates in mice, as compared to the OMVs derived from the wild-type UK-1. In order to enhance OMV production, deletions of ompA or tolR were introduced into rSC0196. The deletion of tolR not only increase the yield of OMVs, but also conferred complete protection against homologous S. Typhimurium challenge in mice. Collectively, these findings indicate that the flagellin-deficient OMVs with a tolR mutation have the potential to serve as a versatile vaccine platform, capable of inducing broad-spectrum protection against significant pathogens.
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Affiliation(s)
- Yichen Tian
- College of Veterinary Medicine, Yangzhou University, Yangzhou, Jiangsu 225009, China; Jiangsu Co-innovation Center for the Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou, Jiangsu 225009, China
| | - Shan Huang
- College of Veterinary Medicine, Yangzhou University, Yangzhou, Jiangsu 225009, China; Jiangsu Co-innovation Center for the Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou, Jiangsu 225009, China
| | - Guodong Zhou
- College of Veterinary Medicine, Yangzhou University, Yangzhou, Jiangsu 225009, China; Jiangsu Co-innovation Center for the Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou, Jiangsu 225009, China
| | - Xia Fei
- College of Veterinary Medicine, Yangzhou University, Yangzhou, Jiangsu 225009, China; Jiangsu Co-innovation Center for the Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou, Jiangsu 225009, China
| | - Yu-An Li
- College of Veterinary Medicine, Yangzhou University, Yangzhou, Jiangsu 225009, China; Jiangsu Co-innovation Center for the Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou, Jiangsu 225009, China
| | - Quan Li
- College of Veterinary Medicine, Yangzhou University, Yangzhou, Jiangsu 225009, China; Jiangsu Co-innovation Center for the Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou, Jiangsu 225009, China.
| | - Shifeng Wang
- Department of Infectious Diseases and Immunology, College of Veterinary Medicine, University of Florida, Gainesville, FL 32611-0880, USA
| | - Huoying Shi
- College of Veterinary Medicine, Yangzhou University, Yangzhou, Jiangsu 225009, China; Jiangsu Co-innovation Center for the Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou, Jiangsu 225009, China; Joint International Research Laboratory of Agriculture & Agri-Product Safety (JIRLAAPS), Yangzhou University, Yangzhou, Jiangsu 225009, China.
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Abstract
This review is focused on describing and analyzing means by which Salmonella enterica serotype strains have been genetically modified with the purpose of developing safe, efficacious vaccines to present Salmonella-induced disease in poultry and to prevent Salmonella colonization of poultry to reduce transmission through the food chain in and on eggs and poultry meat. Emphasis is on use of recently developed means to generate defined deletion mutations to eliminate genetic sequences conferring antimicrobial resistance or residual elements that might lead to genetic instability. Problems associated with prior means to develop vaccines are discussed with presentation of various means by which these problems have been lessened, if not eliminated. Practical considerations are also discussed in hope of facilitating means to move lab-proven successful vaccination procedures and vaccine candidates to the marketplace to benefit the poultry industry.
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Affiliation(s)
- Roy Curtiss
- College of Veterinary Medicine, University of Florida, Gainesville, Florida,
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Pokorzynski ND, Groisman EA. How Bacterial Pathogens Coordinate Appetite with Virulence. Microbiol Mol Biol Rev 2023; 87:e0019822. [PMID: 37358444 PMCID: PMC10521370 DOI: 10.1128/mmbr.00198-22] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/27/2023] Open
Abstract
Cells adjust growth and metabolism to nutrient availability. Having access to a variety of carbon sources during infection of their animal hosts, facultative intracellular pathogens must efficiently prioritize carbon utilization. Here, we discuss how carbon source controls bacterial virulence, with an emphasis on Salmonella enterica serovar Typhimurium, which causes gastroenteritis in immunocompetent humans and a typhoid-like disease in mice, and propose that virulence factors can regulate carbon source prioritization by modifying cellular physiology. On the one hand, bacterial regulators of carbon metabolism control virulence programs, indicating that pathogenic traits appear in response to carbon source availability. On the other hand, signals controlling virulence regulators may impact carbon source utilization, suggesting that stimuli that bacterial pathogens experience within the host can directly impinge on carbon source prioritization. In addition, pathogen-triggered intestinal inflammation can disrupt the gut microbiota and thus the availability of carbon sources. By coordinating virulence factors with carbon utilization determinants, pathogens adopt metabolic pathways that may not be the most energy efficient because such pathways promote resistance to antimicrobial agents and also because host-imposed deprivation of specific nutrients may hinder the operation of certain pathways. We propose that metabolic prioritization by bacteria underlies the pathogenic outcome of an infection.
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Affiliation(s)
- Nick D. Pokorzynski
- Department of Microbial Pathogenesis, Yale School of Medicine, New Haven, Connecticut, USA
| | - Eduardo A. Groisman
- Department of Microbial Pathogenesis, Yale School of Medicine, New Haven, Connecticut, USA
- Yale Microbial Sciences Institute, West Haven, Connecticut, USA
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Xiong L, Wang S, Dean JW, Oliff KN, Jobin C, Curtiss R, Zhou L. Group 3 innate lymphoid cell pyroptosis represents a host defence mechanism against Salmonella infection. Nat Microbiol 2022; 7:1087-1099. [PMID: 35668113 PMCID: PMC9250631 DOI: 10.1038/s41564-022-01142-8] [Citation(s) in RCA: 28] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2021] [Accepted: 05/04/2022] [Indexed: 01/03/2023]
Abstract
Group 3 innate lymphoid cells (ILC3s) produce interleukin (IL)-22 and coordinate with other cells in the gut to mount productive host immunity against bacterial infection. However, the role of ILC3s in Salmonella enterica serovar Typhimurium (S. Typhimurium) infection, which causes foodborne enteritis in humans, remains elusive. Here we show that S. Typhimurium exploits ILC3-produced IL-22 to promote its infection in mice. Specifically, S. Typhimurium secretes flagellin through activation of the TLR5-MyD88-IL-23 signalling pathway in antigen presenting cells (APCs) to selectively enhance IL-22 production by ILC3s, but not T cells. Deletion of ILC3s but not T cells in mice leads to better control of S. Typhimurium infection. We also show that S. Typhimurium can directly invade ILC3s and cause caspase-1-mediated ILC3 pyroptosis independently of flagellin. Genetic ablation of Casp1 in mice leads to increased ILC3 survival and IL-22 production, and enhanced S. Typhimurium infection. Collectively, our data suggest a key host defence mechanism against S. Typhimurium infection via induction of ILC3 death to limit intracellular bacteria and reduce IL-22 production.
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Affiliation(s)
- Lifeng Xiong
- Department of Infectious Diseases and Immunology, College of Veterinary Medicine, University of Florida, Gainesville, FL, USA
| | - Shifeng Wang
- Department of Infectious Diseases and Immunology, College of Veterinary Medicine, University of Florida, Gainesville, FL, USA
| | - Joseph W Dean
- Department of Infectious Diseases and Immunology, College of Veterinary Medicine, University of Florida, Gainesville, FL, USA
| | - Kristen N Oliff
- Department of Infectious Diseases and Immunology, College of Veterinary Medicine, University of Florida, Gainesville, FL, USA
| | - Christian Jobin
- Department of Infectious Diseases and Immunology, College of Veterinary Medicine, University of Florida, Gainesville, FL, USA
- Division of Gastroenterology, Hepatology and Nutrition, College of Medicine, University of Florida, Gainesville, FL, USA
| | - Roy Curtiss
- Department of Infectious Diseases and Immunology, College of Veterinary Medicine, University of Florida, Gainesville, FL, USA
| | - Liang Zhou
- Department of Infectious Diseases and Immunology, College of Veterinary Medicine, University of Florida, Gainesville, FL, USA.
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Impact of the Resistance Responses to Stress Conditions Encountered in Food and Food Processing Environments on the Virulence and Growth Fitness of Non-Typhoidal Salmonellae. Foods 2021; 10:foods10030617. [PMID: 33799446 PMCID: PMC8001757 DOI: 10.3390/foods10030617] [Citation(s) in RCA: 29] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2021] [Revised: 02/24/2021] [Accepted: 03/10/2021] [Indexed: 01/22/2023] Open
Abstract
The success of Salmonella as a foodborne pathogen can probably be attributed to two major features: its remarkable genetic diversity and its extraordinary ability to adapt. Salmonella cells can survive in harsh environments, successfully compete for nutrients, and cause disease once inside the host. Furthermore, they are capable of rapidly reprogramming their metabolism, evolving in a short time from a stress-resistance mode to a growth or virulent mode, or even to express stress resistance and virulence factors at the same time if needed, thanks to a complex and fine-tuned regulatory network. It is nevertheless generally acknowledged that the development of stress resistance usually has a fitness cost for bacterial cells and that induction of stress resistance responses to certain agents can trigger changes in Salmonella virulence. In this review, we summarize and discuss current knowledge concerning the effects that the development of resistance responses to stress conditions encountered in food and food processing environments (including acid, osmotic and oxidative stress, starvation, modified atmospheres, detergents and disinfectants, chilling, heat, and non-thermal technologies) exerts on different aspects of the physiology of non-typhoidal Salmonellae, with special emphasis on virulence and growth fitness.
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Li YA, Chen Y, Du YZ, Guo W, Chu D, Fan J, Wang X, Bellefleur M, Wang S, Shi H. Live-attenuated Salmonella enterica serotype Choleraesuis vaccine with regulated delayed fur mutation confer protection against Streptococcus suis in mice. BMC Vet Res 2020; 16:129. [PMID: 32381017 PMCID: PMC7203871 DOI: 10.1186/s12917-020-02340-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2019] [Accepted: 04/22/2020] [Indexed: 12/17/2022] Open
Abstract
Background Recombinant Salmonella enterica serotype Choleraesuis (S. Choleraesuis) vaccine vector could be used to deliver heterologous antigens to prevent and control pig diseases. We have previously shown that a live-attenuated S. Choleraesuis vaccine candidate strain rSC0011 (ΔPcrp527::TT araC PBADcrp Δpmi-2426 ΔrelA199::araC PBADlacI TT ΔasdA33, Δ, deletion, TT, terminator) delivering SaoA, a conserved surface protein in most of S. suis serotypes, provided excellent protection against S. suis challenge, but occasionally lead to morbidity (enteritidis) in vaccinated mice (approximately 1 in every 10 mice). Thus, alternated attenuation method was sought to reduce the reactogenicity of strain rSC0011. Herein, we described another recombinant attenuated S. Choleraesuis vector, rSC0012 (ΔPfur88:: TT araC PBADfur Δpmi-2426 ΔrelA199:: araC PBADlacI TT ΔasdA33) with regulated delayed fur mutation to avoid inducing disease symptoms while exhibiting a high degree of immunogenicity. Results The strain rSC0012 strain with the ΔPfur88::TT araC PBADfur mutation induced less production of inflammatory cytokines than strain rSC0011 with the ΔPcrp527::TT araC PBADcrp mutation in mice. When delivering the same pS-SaoA plasmid, the intraperitoneal LD50 of rSC0012 was 18.2 times higher than that of rSC0011 in 3-week-old BALB/C mice. rSC0012 with either pS-SaoA or pYA3493 was cleared from spleen and liver tissues 7 days earlier than rSC0011 with same vectors after oral inoculation. The strain rSC0012 synthesizing SaoA induced high titers of anti-SaoA antibodies in both systemic (IgG in serum) and mucosal (IgA in vaginal washes) sites, as well as increased level of IL-4, the facilitator of Th2-type T cell immune response in mice. The recombinant vaccine rSC0012(pS-SaoA) conferred high percentage of protection against S. suis or S. Choleraesuis challenge in BALB/C mice. Conclusions The live-attenuated Salmonella enterica serotype Choleraesuis vaccine rSC0012(pS-SaoA) with regulated delayed fur mutation provides a foundation for the development of a safe and effective vaccine against S. Choleraesuis and S. suis.
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Affiliation(s)
- Yu-An Li
- College of Veterinary Medicine, Yangzhou University, Yangzhou, 225009, Jiangsu, People's Republic of China.,Jiangsu Co-innovation Center for the Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou, 225009, China.,Key Laboratory of Animal Infectious Diseases, Ministry of Agriculture, Yangzhou University, Yangzhou, China.,Jiangsu Key Laboratory of Preventive Veterinary Medicine, Yangzhou University, Yangzhou, China
| | - Yunyun Chen
- College of Veterinary Medicine, Yangzhou University, Yangzhou, 225009, Jiangsu, People's Republic of China.,Jiangsu Co-innovation Center for the Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou, 225009, China.,Key Laboratory of Animal Infectious Diseases, Ministry of Agriculture, Yangzhou University, Yangzhou, China.,Jiangsu Key Laboratory of Preventive Veterinary Medicine, Yangzhou University, Yangzhou, China
| | - Yuan Zhao Du
- Yebio Bioengineering Co., Ltd of Qingdao, Qingdao, 266114, China
| | - Weiwei Guo
- Yebio Bioengineering Co., Ltd of Qingdao, Qingdao, 266114, China
| | - Dianfeng Chu
- Yebio Bioengineering Co., Ltd of Qingdao, Qingdao, 266114, China
| | - Juan Fan
- Yangzhou Uni-Bio Pharmaceutical Co., Ltd, Yangzhou, 225000, Jiangsu, China
| | - Xiaobo Wang
- College of Veterinary Medicine, Yangzhou University, Yangzhou, 225009, Jiangsu, People's Republic of China.,Jiangsu Co-innovation Center for the Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou, 225009, China.,Key Laboratory of Animal Infectious Diseases, Ministry of Agriculture, Yangzhou University, Yangzhou, China.,Jiangsu Key Laboratory of Preventive Veterinary Medicine, Yangzhou University, Yangzhou, China
| | - Matthew Bellefleur
- Department of Infectious Diseases and Immunology, College of Veterinary Medicine, University of Florida, Gainesville, FL, 32611-0880, USA
| | - Shifeng Wang
- Department of Infectious Diseases and Immunology, College of Veterinary Medicine, University of Florida, Gainesville, FL, 32611-0880, USA
| | - Huoying Shi
- College of Veterinary Medicine, Yangzhou University, Yangzhou, 225009, Jiangsu, People's Republic of China. .,Jiangsu Co-innovation Center for the Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou, 225009, China. .,Key Laboratory of Animal Infectious Diseases, Ministry of Agriculture, Yangzhou University, Yangzhou, China. .,Jiangsu Key Laboratory of Preventive Veterinary Medicine, Yangzhou University, Yangzhou, China.
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Sanapala S, Mosca L, Wang S, Curtiss R. Comparative evaluation of Salmonella Typhimurium vaccines derived from UK-1 and 14028S: Importance of inherent virulence. PLoS One 2018; 13:e0203526. [PMID: 30192849 PMCID: PMC6130210 DOI: 10.1371/journal.pone.0203526] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2018] [Accepted: 08/22/2018] [Indexed: 11/18/2022] Open
Abstract
The initial virulence and invasiveness of a bacterial strain may play an important role in leading to a maximally efficacious attenuated live vaccine. Here we show that χ9909, derived from Salmonella Typhimurium UK-1 χ3761 (the most virulent S. Typhimurium strain known to us), is effective in protecting mice against lethal UK-1 and 14028S (less virulent S. Typhimurium strain) challenge. As opposed to this, 14028S-derived vaccine χ12359 induces suboptimal levels of protection, with survival percentages that are significantly lower when challenged with lethal UK-1 challenge doses. T-cell assays have revealed that significantly greater levels of Th1 cytokines IFN-γ and TNF-α were secreted by stimulated T-lymphocytes obtained from UK-1(ΔaroA) immunized mice than those from mice immunized with 14028S(ΔaroA). In addition, UK-1(ΔaroA) showed markedly higher colonizing ability in the spleen, liver, and cecum when compared to 14028S(ΔaroA). Enumeration of bacteria in fecal pellets has also revealed that UK-1(ΔaroA) can persist in the host for over 10 days whereas 14028S(ΔaroA) titers dropped significantly by day 10. Moreover, co-infection of parent strains UK-1 and 14028S resulted in considerably greater recovery of the former in multiple mucosal and gut associated lymphatic tissues. Mice immunized with UK-1(ΔaroA) were also able to clear UK-1 infection remarkably more efficiently from the target organs than 14028S(ΔaroA). Together, these results provide ample evidence to support the hypothesis that attenuated derivatives of parent strains with higher initial virulence make better vaccines.
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Affiliation(s)
- Shilpa Sanapala
- Department of Infectious Disease and Immunology, College of Veterinary Medicine, University of Florida, Gainesville, Florida, United States of America
| | - Leandra Mosca
- Department of Infectious Disease and Immunology, College of Veterinary Medicine, University of Florida, Gainesville, Florida, United States of America
| | - Shifeng Wang
- Department of Infectious Disease and Immunology, College of Veterinary Medicine, University of Florida, Gainesville, Florida, United States of America
| | - Roy Curtiss
- Department of Infectious Disease and Immunology, College of Veterinary Medicine, University of Florida, Gainesville, Florida, United States of America
- * E-mail:
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CRP-cAMP mediates silencing of Salmonella virulence at the post-transcriptional level. PLoS Genet 2018; 14:e1007401. [PMID: 29879120 PMCID: PMC5991649 DOI: 10.1371/journal.pgen.1007401] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2018] [Accepted: 05/09/2018] [Indexed: 12/14/2022] Open
Abstract
Invasion of epithelial cells by Salmonella enterica requires expression of genes located in the pathogenicity island I (SPI-1). The expression of SPI-1 genes is very tightly regulated and activated only under specific conditions. Most studies have focused on the regulatory pathways that induce SPI-1 expression. Here, we describe a new regulatory circuit involving CRP-cAMP, a widely established metabolic regulator, in silencing of SPI-1 genes under non-permissive conditions. In CRP-cAMP-deficient strains we detected a strong upregulation of SPI-1 genes in the mid-logarithmic growth phase. Genetic analyses revealed that CRP-cAMP modulates the level of HilD, the master regulator of Salmonella invasion. This regulation occurs at the post-transcriptional level and requires the presence of a newly identified regulatory motif within the hilD 3'UTR. We further demonstrate that in Salmonella the Hfq-dependent sRNA Spot 42 is under the transcriptional repression of CRP-cAMP and, when this transcriptional repression is relieved, Spot 42 exerts a positive effect on hilD expression. In vivo and in vitro assays indicate that Spot 42 targets, through its unstructured region III, the 3'UTR of the hilD transcript. Together, our results highlight the biological relevance of the hilD 3'UTR as a hub for post-transcriptional control of Salmonella invasion gene expression.
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Clark-Curtiss JE, Curtiss R. Salmonella Vaccines: Conduits for Protective Antigens. THE JOURNAL OF IMMUNOLOGY 2018; 200:39-48. [PMID: 29255088 DOI: 10.4049/jimmunol.1600608] [Citation(s) in RCA: 43] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/06/2016] [Accepted: 11/06/2017] [Indexed: 11/19/2022]
Abstract
Vaccines afford a better and more cost-effective approach to combatting infectious diseases than continued reliance on antibiotics or antiviral or antiparasite drugs in the current era of increasing incidences of diseases caused by drug-resistant pathogens. Recombinant attenuated Salmonella vaccines (RASVs) have been significantly improved to exhibit the same or better attributes than wild-type parental strains to colonize internal lymphoid tissues and persist there to serve as factories to continuously synthesize and deliver rAgs. Encoded by codon-optimized pathogen genes, Ags are selected to induce protective immunity to infection by that pathogen. After immunization through a mucosal surface, the RASV attributes maximize their abilities to elicit mucosal and systemic Ab responses and cell-mediated immune responses. This article summarizes many of the numerous innovative technologies and discoveries that have resulted in RASV platforms that will enable development of safe efficacious RASVs to protect animals and humans against a diversity of infectious disease agents.
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Affiliation(s)
- Josephine E Clark-Curtiss
- Division of Infectious Diseases and Global Medicine, Department of Medicine, College of Medicine, University of Florida, Gainesville, FL 32610.,Emerging Pathogens Institute, University of Florida, Gainesville, FL 32611
| | - Roy Curtiss
- Department of Infectious Diseases and Immunology, College of Veterinary Medicine, University of Florida, Gainesville, FL 32611; and .,Department of Comparative, Diagnostic and Population Medicine, College of Veterinary Medicine, University of Florida, Gainesville, FL 32611
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11
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Bacterial membrane vesicles transport their DNA cargo into host cells. Sci Rep 2017; 7:7072. [PMID: 28765539 PMCID: PMC5539193 DOI: 10.1038/s41598-017-07288-4] [Citation(s) in RCA: 216] [Impact Index Per Article: 30.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2016] [Accepted: 06/27/2017] [Indexed: 12/25/2022] Open
Abstract
Bacterial outer membrane vesicles (OMVs) are extracellular sacs containing biologically active products, such as proteins, cell wall components and toxins. OMVs are reported to contain DNA, however, little is known about the nature of this DNA, nor whether it can be transported into host cells. Our work demonstrates that chromosomal DNA is packaged into OMVs shed by bacteria during exponential phase. Most of this DNA was present on the external surfaces of OMVs, with smaller amounts located internally. The DNA within the internal compartments of Pseudomonas aeruginosa OMVs were consistently enriched in specific regions of the bacterial chromosome, encoding proteins involved in virulence, stress response, antibiotic resistance and metabolism. Furthermore, we demonstrated that OMVs carry DNA into eukaryotic cells, and this DNA was detectable by PCR in the nuclear fraction of cells. These findings suggest a role for OMV-associated DNA in bacterial-host cell interactions and have implications for OMV-based vaccines.
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Lin Z, Tang P, Jiao Y, Kang X, Li Q, Xu X, Sun J, Pan Z, Jiao X. Immunogenicity and protective efficacy of a Salmonella Enteritidis sptP mutant as a live attenuated vaccine candidate. BMC Vet Res 2017. [PMID: 28646853 PMCID: PMC5483252 DOI: 10.1186/s12917-017-1115-3] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Background Salmonella enterica serovar Enteritidis (S. Enteritidis) is a highly adaptive pathogen in both humans and animals. As a Salmonella Type III secretion system (T3SS) effector, Salmonella protein tyrosine phosphatase (SptP) is critical for virulence in this genus. To investigate the feasibility of using C50336ΔsptP as a live attenuated oral vaccine in mice, we generated the sptP gene deletion mutant C50336ΔsptP in S. Enteritidis strain C50336 by λ-Red mediated recombination and evaluated the protective ability of the S. Enteritidis sptP mutant strain C50336ΔsptP against mice salmonellosis. Results We found that C50336ΔsptP was a highly immunogenic, effective, and safe vaccine in mice. Compared to wild-type C50336, C50336ΔsptP showed reduced virulence as confirmed by the 50% lethal dose (LD50) in orally infected mice. C50336ΔsptP also showed decreased bacterial colonization both in vivo and in vitro. Immunization with C50336ΔsptP had no significant effect on body weight and did not result in obvious clinical symptoms relative to control animals treated with phosphate-buffered saline (PBS), but induced humoral and cellular immune responses at 12 and 26 days post inoculation. Immunization with 1 × 108 colony-forming units (CFU) C50336ΔsptP per mouse provided 100% protection against subsequent challenge with the wild-type C50336 strain, and immunized mice showed mild and temporary clinical symptoms as compared to those of control group. Conclusions These results demonstrate that C50336ΔsptP can be a live attenuated oral vaccine for salmonellosis.
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Affiliation(s)
- Zhijie Lin
- Jiangsu Key Laboratory of Zoonosis, Jiangsu Co-Innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonosis, MOA Key Laboratory of Prevention and Control of Biological Hazard Factors (Animal Origin) for Agrifood Safety and Quality, MOE Joint International Research Laboratory of Agriculture and Agri-product Safety, Yangzhou University, Yangzhou, 225001, China
| | - Peipei Tang
- Jiangsu Key Laboratory of Zoonosis, Jiangsu Co-Innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonosis, MOA Key Laboratory of Prevention and Control of Biological Hazard Factors (Animal Origin) for Agrifood Safety and Quality, MOE Joint International Research Laboratory of Agriculture and Agri-product Safety, Yangzhou University, Yangzhou, 225001, China
| | - Yang Jiao
- Jiangsu Key Laboratory of Zoonosis, Jiangsu Co-Innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonosis, MOA Key Laboratory of Prevention and Control of Biological Hazard Factors (Animal Origin) for Agrifood Safety and Quality, MOE Joint International Research Laboratory of Agriculture and Agri-product Safety, Yangzhou University, Yangzhou, 225001, China
| | - Xilong Kang
- Jiangsu Key Laboratory of Zoonosis, Jiangsu Co-Innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonosis, MOA Key Laboratory of Prevention and Control of Biological Hazard Factors (Animal Origin) for Agrifood Safety and Quality, MOE Joint International Research Laboratory of Agriculture and Agri-product Safety, Yangzhou University, Yangzhou, 225001, China
| | - Qiuchun Li
- Jiangsu Key Laboratory of Zoonosis, Jiangsu Co-Innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonosis, MOA Key Laboratory of Prevention and Control of Biological Hazard Factors (Animal Origin) for Agrifood Safety and Quality, MOE Joint International Research Laboratory of Agriculture and Agri-product Safety, Yangzhou University, Yangzhou, 225001, China
| | - Xiulong Xu
- Jiangsu Key Laboratory of Zoonosis, Jiangsu Co-Innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonosis, MOA Key Laboratory of Prevention and Control of Biological Hazard Factors (Animal Origin) for Agrifood Safety and Quality, MOE Joint International Research Laboratory of Agriculture and Agri-product Safety, Yangzhou University, Yangzhou, 225001, China.,Center for Comparative Medicine, Animal Infectious Disease Laboratory, College of Veterinary Medicine, Yangzhou University, Yangzhou, 225001, China.,Department of Anatomy and Cell Biology, Rush University Medical Center, Chicago, 60612, USA
| | - Jun Sun
- Jiangsu Key Laboratory of Zoonosis, Jiangsu Co-Innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonosis, MOA Key Laboratory of Prevention and Control of Biological Hazard Factors (Animal Origin) for Agrifood Safety and Quality, MOE Joint International Research Laboratory of Agriculture and Agri-product Safety, Yangzhou University, Yangzhou, 225001, China.,Division of Gastroenterology and Hepatology, College of Medicine, University of Illinois at Chicago, Chicago, 60612, USA
| | - Zhiming Pan
- Jiangsu Key Laboratory of Zoonosis, Jiangsu Co-Innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonosis, MOA Key Laboratory of Prevention and Control of Biological Hazard Factors (Animal Origin) for Agrifood Safety and Quality, MOE Joint International Research Laboratory of Agriculture and Agri-product Safety, Yangzhou University, Yangzhou, 225001, China.
| | - Xinan Jiao
- Jiangsu Key Laboratory of Zoonosis, Jiangsu Co-Innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonosis, MOA Key Laboratory of Prevention and Control of Biological Hazard Factors (Animal Origin) for Agrifood Safety and Quality, MOE Joint International Research Laboratory of Agriculture and Agri-product Safety, Yangzhou University, Yangzhou, 225001, China.
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13
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Erova TE, Kirtley ML, Fitts EC, Ponnusamy D, Baze WB, Andersson JA, Cong Y, Tiner BL, Sha J, Chopra AK. Protective Immunity Elicited by Oral Immunization of Mice with Salmonella enterica Serovar Typhimurium Braun Lipoprotein (Lpp) and Acetyltransferase (MsbB) Mutants. Front Cell Infect Microbiol 2016; 6:148. [PMID: 27891321 PMCID: PMC5103298 DOI: 10.3389/fcimb.2016.00148] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2016] [Accepted: 10/27/2016] [Indexed: 12/12/2022] Open
Abstract
We evaluated the extent of attenuation and immunogenicity of the ΔlppAB and ΔlppAB ΔmsbB mutants of Salmonella enterica serovar Typhimurium when delivered to mice by the oral route. These mutants were deleted either for the Braun lipoprotein genes (lppA and lppB) or in combination with the msbB gene, which encodes an acetyltransferase required for lipid A modification of lipopolysaccharide. Both the mutants were attenuated (100% animal survival) and triggered robust innate and adaptive immune responses. Comparable levels of IgG and its isotypes were produced in mice infected with wild-type (WT) S. typhimurium or its aforementioned mutant strains. The ΔlppAB ΔmsbB mutant-immunized animals resulted in the production of higher levels of fecal IgA and serum cytokines during later stages of vaccination (adaptive response). A significant production of interleukin-6 from T-cells was also noted in the ΔlppAB ΔmsbB mutant-immunized mice when compared to that of the ΔlppAB mutant. On the other hand, IL-17A production was significantly more in the serum of ΔlppAB mutant-immunized mice (innate response) with a stronger splenic T-cell proliferative and tumor-necrosis factor-α production. Based on 2-dimensional gel analysis, alterations in the levels of several proteins were observed in both the mutant strains when compared to that in WT S. typhimurium and could be associated with the higher immunogenicity of the mutants. Finally, both ΔlppAB and ΔlppAB ΔmsbB mutants provided complete protection to immunized mice against a lethal oral challenge dose of WT S. typhimurium. Thus, these mutants may serve as excellent vaccine candidates and also provide a platform for delivering heterologous antigens.
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Affiliation(s)
- Tatiana E Erova
- Department of Microbiology and Immunology, University of Texas Medical Branch Galveston, TX, USA
| | - Michelle L Kirtley
- Department of Microbiology and Immunology, University of Texas Medical Branch Galveston, TX, USA
| | - Eric C Fitts
- Department of Microbiology and Immunology, University of Texas Medical Branch Galveston, TX, USA
| | - Duraisamy Ponnusamy
- Department of Microbiology and Immunology, University of Texas Medical Branch Galveston, TX, USA
| | - Wallace B Baze
- Department of Veterinary Sciences, University of Texas M. D. Anderson Cancer Center Bastrop, TX, USA
| | - Jourdan A Andersson
- Department of Microbiology and Immunology, University of Texas Medical Branch Galveston, TX, USA
| | - Yingzi Cong
- Department of Microbiology and Immunology, University of Texas Medical BranchGalveston, TX, USA; Institute for Human Infections and Immunity, University of Texas Medical BranchGalveston, TX, USA; Sealy Center for Vaccine Development and World Health Organisation Collaborating Center for Vaccine Research, University of Texas Medical BranchGalveston, TX, USA; Center for Biodefense and Emerging Infectious Diseases, University of Texas Medical BranchGalveston, TX, USA
| | - Bethany L Tiner
- Department of Microbiology and Immunology, University of Texas Medical Branch Galveston, TX, USA
| | - Jian Sha
- Department of Microbiology and Immunology, University of Texas Medical BranchGalveston, TX, USA; Institute for Human Infections and Immunity, University of Texas Medical BranchGalveston, TX, USA
| | - Ashok K Chopra
- Department of Microbiology and Immunology, University of Texas Medical BranchGalveston, TX, USA; Institute for Human Infections and Immunity, University of Texas Medical BranchGalveston, TX, USA; Sealy Center for Vaccine Development and World Health Organisation Collaborating Center for Vaccine Research, University of Texas Medical BranchGalveston, TX, USA; Center for Biodefense and Emerging Infectious Diseases, University of Texas Medical BranchGalveston, TX, USA
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14
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Bridge DR, Whitmire JM, Makobongo MO, Merrell DS. Heterologous Pseudomonas aeruginosa O-antigen delivery using a Salmonella enterica serovar Typhimurium wecA mutant strain. Int J Med Microbiol 2016; 306:529-540. [PMID: 27476047 DOI: 10.1016/j.ijmm.2016.06.005] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2016] [Revised: 06/22/2016] [Accepted: 06/27/2016] [Indexed: 01/30/2023] Open
Abstract
There is a broad interest in adapting live vaccine strains (LVS) for use as recombinant vaccines that can deliver heterologous antigens. The Salmonella enterica serovar Typhimurium SL1344 ΔwecA LVS contains a mutation in wecA that abrogates production of Enterobacterial common antigen. This ΔwecA strain is attenuated in vivo, persistently colonizes the host, and protects against both wild type and cross-Salmonella serovar lethal challenge in a murine model of salmonellosis. Given these characteristics, we hypothesized that the SL1344 ΔwecA strain could be used as a carrier for heterologous antigen expression. To test this hypothesis, SL1344 ΔwecA was engineered to express the Pseudomonas aeruginosa O11 O-antigen gene cluster. Intraperitoneal (IP) but not oral immunization of BALB/c mice with the heterologous expression strain protected against lethal P. aeruginosa intranasal (IN) challenge. Furthermore, IP immunization resulted in P. aeruginosa O11-specific Ig and IgG antibody production. Functional analysis of sera collected from the IP immunized mice showed antibody-mediated agglutination and opsonophagocytic activity against P. aeruginosa. En masse, these results indicate that the S. Typhimurium SL1344 ΔwecA strain expressing the P. aeruginosa O11 O-antigen gene cluster is able to induce a humoral immune response and to protect against lethal P. aeruginosa challenge. As such, the S. Typhimurium SL1344 ΔwecA LVS can likely serve as a vehicle for expression of a wide variety of heterologous antigens as a means to create recombinant vaccines.
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Affiliation(s)
- Dacie R Bridge
- Department of Microbiology and Immunology, F. Edward Hébert School of Medicine, Uniformed Services University of the Health Sciences, 4301 Jones Bridge Road, Bethesda, MD 20814, United States.
| | - Jeannette M Whitmire
- Department of Microbiology and Immunology, F. Edward Hébert School of Medicine, Uniformed Services University of the Health Sciences, 4301 Jones Bridge Road, Bethesda, MD 20814, United States.
| | - Morris O Makobongo
- Department of Microbiology and Immunology, F. Edward Hébert School of Medicine, Uniformed Services University of the Health Sciences, 4301 Jones Bridge Road, Bethesda, MD 20814, United States.
| | - D Scott Merrell
- Department of Microbiology and Immunology, F. Edward Hébert School of Medicine, Uniformed Services University of the Health Sciences, 4301 Jones Bridge Road, Bethesda, MD 20814, United States.
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15
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Felgner S, Kocijancic D, Frahm M, Curtiss R, Erhardt M, Weiss S. Optimizing Salmonella enterica serovar Typhimurium for bacteria-mediated tumor therapy. Gut Microbes 2016; 7:171-7. [PMID: 26939530 PMCID: PMC4856459 DOI: 10.1080/19490976.2016.1155021] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
Bacteria-mediated tumor therapy using Salmonella enterica serovar Typhimurium is a therapeutic option with great potential. Numerous studies explored the potential of Salmonella Typhimurium for therapeutic applications, however reconciling safety with vectorial efficacy remains a major issue. Recently we have described a conditionally attenuated Salmonella vector that is based on genetic lipopolysaccharide modification. This vector combines strong attenuation with appropriate anti-tumor properties by targeting various cancerous tissues in vivo. Therefore, it was promoted as an anti-tumor agent. In this addendum, we summarize these findings and demonstrate additional optimization steps that may further improve the therapeutic efficacy of our vector strain.
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Affiliation(s)
- Sebastian Felgner
- Department of Molecular Immunology, Helmholtz Centre for Infection Research, Braunschweig, Germany
| | - Dino Kocijancic
- Department of Molecular Immunology, Helmholtz Centre for Infection Research, Braunschweig, Germany
| | - Michael Frahm
- Department of Molecular Immunology, Helmholtz Centre for Infection Research, Braunschweig, Germany
| | - Roy Curtiss
- Department of Infectious Diseases and Pathology, University of Florida, Gainesville, USA
| | - Marc Erhardt
- Junior Research Group Infection Biology of Salmonella, Helmholtz Centre for Infection Research, Braunschweig, Germany
| | - Siegfried Weiss
- Department of Molecular Immunology, Helmholtz Centre for Infection Research, Braunschweig, Germany,Institute of Immunology, Medical School Hannover, Hannover, Germany
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16
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Strategies to Block Bacterial Pathogenesis by Interference with Motility and Chemotaxis. Curr Top Microbiol Immunol 2016; 398:185-205. [PMID: 27000091 DOI: 10.1007/82_2016_493] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Infections by motile, pathogenic bacteria, such as Campylobacter species, Clostridium species, Escherichia coli, Helicobacter pylori, Listeria monocytogenes, Neisseria gonorrhoeae, Pseudomonas aeruginosa, Salmonella species, Vibrio cholerae, and Yersinia species, represent a severe economic and health problem worldwide. Of special importance in this context is the increasing emergence and spread of multidrug-resistant bacteria. Due to the shortage of effective antibiotics for the treatment of infections caused by multidrug-resistant, pathogenic bacteria, the targeting of novel, virulence-relevant factors constitutes a promising, alternative approach. Bacteria have evolved distinct motility structures for movement across surfaces and in aqueous environments. In this review, I will focus on the bacterial flagellum, the associated chemosensory system, and the type-IV pilus as motility devices, which are crucial for bacterial pathogens to reach a preferred site of infection, facilitate biofilm formation, and adhere to surfaces or host cells. Thus, those nanomachines constitute potential targets for the development of novel anti-infectives that are urgently needed at a time of spreading antibiotic resistance. Both bacterial flagella and type-IV pili (T4P) are intricate macromolecular complexes made of dozens of different proteins and their motility function relies on the correct spatial and temporal assembly of various substructures. Specific type-III and type-IV secretion systems power the export of substrate proteins of the bacterial flagellum and type-IV pilus, respectively, and are homologous to virulence-associated type-III and type-II secretion systems. Accordingly, bacterial flagella and T4P represent attractive targets for novel antivirulence drugs interfering with synthesis, assembly, and function of these motility structures.
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17
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Erhardt M, Dersch P. Regulatory principles governing Salmonella and Yersinia virulence. Front Microbiol 2015; 6:949. [PMID: 26441883 PMCID: PMC4563271 DOI: 10.3389/fmicb.2015.00949] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2015] [Accepted: 08/27/2015] [Indexed: 11/13/2022] Open
Abstract
Enteric pathogens such as Salmonella and Yersinia evolved numerous strategies to survive and proliferate in different environmental reservoirs and mammalian hosts. Deciphering common and pathogen-specific principles for how these bacteria adjust and coordinate spatiotemporal expression of virulence determinants, stress adaptation, and metabolic functions is fundamental to understand microbial pathogenesis. In order to manage sudden environmental changes, attacks by the host immune systems and microbial competition, the pathogens employ a plethora of transcriptional and post-transcriptional control elements, including transcription factors, sensory and regulatory RNAs, RNAses, and proteases, to fine-tune and control complex gene regulatory networks. Many of the contributing global regulators and the molecular mechanisms of regulation are frequently conserved between Yersinia and Salmonella. However, the interplay, arrangement, and composition of the control elements vary between these closely related enteric pathogens, which generate phenotypic differences leading to distinct pathogenic properties. In this overview we present common and different regulatory networks used by Salmonella and Yersinia to coordinate the expression of crucial motility, cell adhesion and invasion determinants, immune defense strategies, and metabolic adaptation processes. We highlight evolutionary changes of the gene regulatory circuits that result in different properties of the regulatory elements and how this influences the overall outcome of the infection process.
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Affiliation(s)
- Marc Erhardt
- Young Investigator Group Infection Biology of Salmonella, Helmholtz Centre for Infection Research Braunschweig, Germany
| | - Petra Dersch
- Department of Molecular Infection Biology, Helmholtz Centre for Infection Research Braunschweig, Germany
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18
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Tennant SM, Levine MM. Live attenuated vaccines for invasive Salmonella infections. Vaccine 2015; 33 Suppl 3:C36-41. [PMID: 25902362 PMCID: PMC4469493 DOI: 10.1016/j.vaccine.2015.04.029] [Citation(s) in RCA: 58] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2015] [Revised: 04/06/2015] [Accepted: 04/08/2015] [Indexed: 02/04/2023]
Abstract
Salmonella enterica serovar Typhi produces significant morbidity and mortality worldwide despite the fact that there are licensed Salmonella Typhi vaccines available. This is primarily due to the fact that these vaccines are not used in the countries that most need them. There is growing recognition that an effective invasive Salmonella vaccine formulation must also prevent infection due to other Salmonella serovars. We anticipate that a multivalent vaccine that targets the following serovars will be needed to control invasive Salmonella infections worldwide: Salmonella Typhi, Salmonella Paratyphi A, Salmonella Paratyphi B (currently uncommon but may become dominant again), Salmonella Typhimurium, Salmonella Enteritidis and Salmonella Choleraesuis (as well as other Group C Salmonella). Live attenuated vaccines are an attractive vaccine formulation for use in developing as well as developed countries. Here, we describe the methods of attenuation that have been used to date to create live attenuated Salmonella vaccines and provide an update on the progress that has been made on these vaccines.
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Affiliation(s)
- Sharon M Tennant
- Center for Vaccine Development, University of Maryland School of Medicine, Baltimore, MD, USA; Department of Medicine, University of Maryland School of Medicine, Baltimore, MD, USA.
| | - Myron M Levine
- Center for Vaccine Development, University of Maryland School of Medicine, Baltimore, MD, USA; Department of Medicine, University of Maryland School of Medicine, Baltimore, MD, USA; Department of Pediatrics, University of Maryland School of Medicine, Baltimore, MD, USA.
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19
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Dhanani AS, Block G, Dewar K, Forgetta V, Topp E, Beiko RG, Diarra MS. Genomic Comparison of Non-Typhoidal Salmonella enterica Serovars Typhimurium, Enteritidis, Heidelberg, Hadar and Kentucky Isolates from Broiler Chickens. PLoS One 2015; 10:e0128773. [PMID: 26083489 PMCID: PMC4470630 DOI: 10.1371/journal.pone.0128773] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2014] [Accepted: 05/01/2015] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND Non-typhoidal Salmonella enterica serovars, associated with different foods including poultry products, are important causes of bacterial gastroenteritis worldwide. The colonization of the chicken gut by S. enterica could result in the contamination of the environment and food chain. The aim of this study was to compare the genomes of 25 S. enterica serovars isolated from broiler chicken farms to assess their intra- and inter-genetic variability, with a focus on virulence and antibiotic resistance characteristics. METHODOLOGY/PRINCIPAL FINDING The genomes of 25 S. enterica isolates covering five serovars (ten Typhimurium including three monophasic 4,[5],12:i:, four Enteritidis, three Hadar, four Heidelberg and four Kentucky) were sequenced. Most serovars were clustered in strongly supported phylogenetic clades, except for isolates of serovar Enteritidis that were scattered throughout the tree. Plasmids of varying sizes were detected in several isolates independently of serovars. Genes associated with the IncF plasmid and the IncI1 plasmid were identified in twelve and four isolates, respectively, while genes associated with the IncQ plasmid were found in one isolate. The presence of numerous genes associated with Salmonella pathogenicity islands (SPIs) was also confirmed. Components of the type III and IV secretion systems (T3SS and T4SS) varied in different isolates, which could explain in part, differences of their pathogenicity in humans and/or persistence in broilers. Conserved clusters of genes in the T3SS were detected that could be used in designing effective strategies (diagnostic, vaccination or treatments) to combat Salmonella. Antibiotic resistance genes (CMY, aadA, ampC, florR, sul1, sulI, tetAB, and srtA) and class I integrons were detected in resistant isolates while all isolates carried multidrug efflux pump systems regardless of their antibiotic susceptibility profile. CONCLUSIONS/SIGNIFICANCE This study showed that the predominant Salmonella serovars in broiler chickens harbor genes encoding adhesins, flagellar proteins, T3SS, iron acquisition systems, and antibiotic and metal resistance genes that may explain their pathogenicity, colonization ability and persistence in chicken. The existence of mobile genetic elements indicates that isolates from a given serovar could acquire and transfer genetic material. Conserved genes in the T3SS and T4SS that we have identified are promising candidates for identification of diagnostic, antimicrobial or vaccine targets for the control of Salmonella in broiler chickens.
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Affiliation(s)
- Akhilesh S. Dhanani
- Faculty of Computer Science, Dalhousie University, Halifax, Nova Scotia, B3H 4R2, Canada
| | - Glenn Block
- Pacific Agri-Food Research Center, Agriculture and Agri-Food Canada (AAFC), Agassiz, British Columbia, V0M 1A0, Canada
| | - Ken Dewar
- McGill University and Genome Quebec Innovation Centre, Montreal, Quebec, H3A 1A4, Canada
| | - Vincenzo Forgetta
- Lady Davis Institute for Medical Research, Montréal, Québec, H3T 1E2, Canada
| | - Edward Topp
- Southern Crop Protection and Food Research Centre, AAFC, London, Ontario, N5V 4T3, Canada
| | - Robert G. Beiko
- Faculty of Computer Science, Dalhousie University, Halifax, Nova Scotia, B3H 4R2, Canada
| | - Moussa S. Diarra
- Pacific Agri-Food Research Center, Agriculture and Agri-Food Canada (AAFC), Agassiz, British Columbia, V0M 1A0, Canada
- * E-mail:
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20
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Bridge DR, Whitmire JM, Gilbreath JJ, Metcalf ES, Merrell DS. An enterobacterial common antigen mutant of Salmonella enterica serovar Typhimurium as a vaccine candidate. Int J Med Microbiol 2015; 305:511-22. [PMID: 26070977 DOI: 10.1016/j.ijmm.2015.05.004] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2014] [Revised: 05/15/2015] [Accepted: 05/26/2015] [Indexed: 11/19/2022] Open
Abstract
Due to increasing rates of invasive Salmonella enterica serovar Typhimurium infection, there is a need for an effective vaccine to prevent this disease. Previous studies showed that a mutation in the first gene of the Enterobacterial common antigen biosynthetic pathway, wecA, resulted in attenuation of S. Typhimurium in a murine model of salmonellosis. Furthermore, immunization with a wecA(-) strain protected against lethal challenge with the parental wild type S. Typhimurium strain. Herein, we examined whether the S. Typhimurium wecA(-) strain could also provide cross-protection against non-parental strains of S. Typhimurium and S. Enteritidis. We found that intraperitoneal immunization (IP) with S. Typhimurium SL1344 wecA(-) resulted in a significant increase in survival compared to control mice for all Salmonella challenge strains tested. Oral immunization with SL1344 wecA(-) also resulted in increased survival; however, protection was less significant than with intraperitoneal immunization. The increase in survival of SL1344 wecA(-) immunized mice was associated with a Salmonella-specific IgG antibody response. Furthermore, analysis of sera from IP and orally immunized animals revealed cross-reactive antibodies to numerous Salmonella isolates. Functional analysis of antibodies found within the sera from IP immunized animals revealed agglutination and opsonophagocytic activity against all tested O:4 Salmonella serovars. Together these results indicate that immunization with a S. Typhimurium wecA(-) strain confers protection against lethal challenge with wild type S. Typhimurium and S. Enteritidis and that immunization correlates with functional antibody production.
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Affiliation(s)
- Dacie R Bridge
- Department of Microbiology and Immunology, F. Edward Hébert School of Medicine, Uniformed Services University of the Health Sciences, 4301 Jones Bridge Road, Bethesda, MD 20814, USA.
| | - Jeannette M Whitmire
- Department of Microbiology and Immunology, F. Edward Hébert School of Medicine, Uniformed Services University of the Health Sciences, 4301 Jones Bridge Road, Bethesda, MD 20814, USA.
| | - Jeremy J Gilbreath
- Department of Microbiology and Immunology, F. Edward Hébert School of Medicine, Uniformed Services University of the Health Sciences, 4301 Jones Bridge Road, Bethesda, MD 20814, USA.
| | - Eleanor S Metcalf
- Department of Microbiology and Immunology, F. Edward Hébert School of Medicine, Uniformed Services University of the Health Sciences, 4301 Jones Bridge Road, Bethesda, MD 20814, USA.
| | - D Scott Merrell
- Department of Microbiology and Immunology, F. Edward Hébert School of Medicine, Uniformed Services University of the Health Sciences, 4301 Jones Bridge Road, Bethesda, MD 20814, USA.
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21
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Zhang X, Kong W, Wanda SY, Xin W, Alamuri P, Curtiss R. Generation of influenza virus from avian cells infected by Salmonella carrying the viral genome. PLoS One 2015; 10:e0119041. [PMID: 25742162 PMCID: PMC4351096 DOI: 10.1371/journal.pone.0119041] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2014] [Accepted: 01/09/2015] [Indexed: 12/14/2022] Open
Abstract
Domestic poultry serve as intermediates for transmission of influenza A virus from the wild aquatic bird reservoir to humans, resulting in influenza outbreaks in poultry and potential epidemics/pandemics among human beings. To combat emerging avian influenza virus, an inexpensive, heat-stable, and orally administered influenza vaccine would be useful to vaccinate large commercial poultry flocks and even migratory birds. Our hypothesized vaccine is a recombinant attenuated bacterial strain able to mediate production of attenuated influenza virus in vivo to induce protective immunity against influenza. Here we report the feasibility and technical limitations toward such an ideal vaccine based on our exploratory study. Five 8-unit plasmids carrying a chloramphenicol resistance gene or free of an antibiotic resistance marker were constructed. Influenza virus was successfully generated in avian cells transfected by each of the plasmids. The Salmonella carrier was engineered to allow stable maintenance and conditional release of the 8-unit plasmid into the avian cells for recovery of influenza virus. Influenza A virus up to 10⁷ 50% tissue culture infective doses (TCID50)/ml were recovered from 11 out of 26 co-cultures of chicken embryonic fibroblasts (CEF) and Madin-Darby canine kidney (MDCK) cells upon infection by the recombinant Salmonella carrying the 8-unit plasmid. Our data prove that a bacterial carrier can mediate generation of influenza virus by delivering its DNA cargoes into permissive host cells. Although we have made progress in developing this Salmonella influenza virus vaccine delivery system, further improvements are necessary to achieve efficient virus production, especially in vivo.
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Affiliation(s)
- Xiangmin Zhang
- The Biodesign Institute, Arizona State University, Tempe, Arizona, United States of America
- Department of Pharmaceutical Sciences, Eugene Applebaum College of Pharmacy/Health Sciences, Wayne State University, Detroit, Michigan, United States of America
- * E-mail:
| | - Wei Kong
- The Biodesign Institute, Arizona State University, Tempe, Arizona, United States of America
| | - Soo-Young Wanda
- The Biodesign Institute, Arizona State University, Tempe, Arizona, United States of America
| | - Wei Xin
- The Biodesign Institute, Arizona State University, Tempe, Arizona, United States of America
| | - Praveen Alamuri
- The Biodesign Institute, Arizona State University, Tempe, Arizona, United States of America
| | - Roy Curtiss
- The Biodesign Institute, Arizona State University, Tempe, Arizona, United States of America
- School of Life Science, Arizona State University, Tempe, Arizona, United States of America
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Yun J, Fan X, Li X, Jin TZ, Jia X, Mattheis JP. Natural surface coating to inactivate Salmonella enterica serovar Typhimurium and maintain quality of cherry tomatoes. Int J Food Microbiol 2015; 193:59-67. [DOI: 10.1016/j.ijfoodmicro.2014.10.013] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2014] [Revised: 10/06/2014] [Accepted: 10/11/2014] [Indexed: 11/16/2022]
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Abstract
This chapter reviews papers mostly written since 2005 that report results using live attenuated bacterial vectors to deliver after administration through mucosal surfaces, protective antigens, and DNA vaccines, encoding protective antigens to induce immune responses and/or protective immunity to pathogens that colonize on or invade through mucosal surfaces. Papers that report use of such vaccine vector systems for parenteral vaccination or to deal with nonmucosal pathogens or do not address induction of mucosal antibody and/or cellular immune responses are not reviewed.
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Jofré MR, Rodríguez LM, Villagra NA, Hidalgo AA, Mora GC, Fuentes JA. RpoS integrates CRP, Fis, and PhoP signaling pathways to control Salmonella Typhi hlyE expression. BMC Microbiol 2014; 14:139. [PMID: 24885225 PMCID: PMC4105832 DOI: 10.1186/1471-2180-14-139] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2013] [Accepted: 05/21/2014] [Indexed: 12/26/2022] Open
Abstract
BACKGROUND SPI-18 is a pathogenicity island found in some Salmonella enterica serovars, including S. Typhi. SPI-18 harbors two ORFs organized into an operon, hlyE and taiA genes, both implicated in virulence. Regarding the hlyE regulation in S. Typhi, it has been reported that RpoS participates as transcriptional up-regulator under low pH and high osmolarity. In addition, CRP down-regulates hlyE expression during exponential growth. Previously, it has been suggested that there is another factor related to catabolite repression, different from CRP, involved in the down-regulation of hlyE. Moreover, PhoP-dependent hlyE up-regulation has been reported in bacteria cultured simultaneously under low pH and low concentration of Mg2+. Nevertheless, the relative contribution of each environmental signal is not completely clear. In this work we aimed to better understand the regulation of hlyE in S. Typhi and the integration of different environmental signals through global regulators. RESULTS We found that Fis participates as a CRP-independent glucose-dependent down-regulator of hlyE. Also, Fis and CRP seem to exert the repression over hlyE through down-regulating rpoS. Moreover, PhoP up-regulates hlyE expression via rpoS under low pH and low Mg2+ conditions. CONCLUSIONS All these results together show that, at least under the tested conditions, RpoS is the central regulator in the hlyE regulatory network, integrating multiple environmental signals and global regulators.
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Affiliation(s)
| | | | | | | | | | - Juan A Fuentes
- Facultad de Ciencias Biológicas, Universidad Andres Bello, Santiago, Chile.
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Identification and characterization of a novel flagellum-dependent Salmonella-infecting bacteriophage, iEPS5. Appl Environ Microbiol 2013; 79:4829-37. [PMID: 23747700 DOI: 10.1128/aem.00706-13] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
A novel flagellatropic phage of Salmonella enterica serovar Typhimurium, called iEPS5, was isolated and characterized. iEPS5 has an icosahedral head and a long noncontractile tail with a tail fiber. Genome sequencing revealed a double-stranded DNA of 59,254 bp having 73 open reading frames (ORFs). To identify the receptor for iEPS5, Tn5 transposon insertion mutants of S. Typhimurium SL1344 that were resistant to the phage were isolated. All of the phage-resistant mutants were found to have mutations in genes involved in flagellar formation, suggesting that the flagellum is the adsorption target of this phage. Analysis of phage infection using the ΔmotA mutant, which is flagellated but nonmotile, demonstrated the requirement of flagellar rotation for iEPS5 infection. Further analysis of phage infection using the ΔcheY mutant revealed that iEPS5 could infect host bacteria only when the flagellum is rotating counterclockwise (CCW). These results suggested that the CCW-rotating flagellar filament is essential for phage adsorption and required for successful infection by iEPS5. In contrast to the well-studied flagellatropic phage Chi, iEPS5 cannot infect the ΔfliK mutant that makes a polyhook without a flagellar filament, suggesting that these two flagellatropic phages utilize different infection mechanisms. Here, we present evidence that iEPS5 injects its DNA into the flagellar filament for infection by assessing DNA transfer from SYBR gold-labeled iEPS5 to the host bacteria.
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Yun J, Fan X, Li X. Inactivation of Salmonella enterica serovar Typhimurium and quality maintenance of cherry tomatoes treated with gaseous essential oils. J Food Sci 2013; 78:M458-64. [PMID: 23398191 DOI: 10.1111/1750-3841.12052] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2012] [Accepted: 12/07/2012] [Indexed: 10/27/2022]
Abstract
The antimicrobial activity of the essential oils (EOs) from cinnamon bark, oregano, mustard, and of their major components cinnamaldehyde, carvacrol, and allyl isothiocyanate (AIT) was evaluated as a gaseous treatment to reduce Salmonella enterica serovar Typhimurium in vitro and on tomatoes. In vitro tests showed that mustard EO and AIT had the greatest inhibition of Salmonella, followed by cinnamon EO and cinnamaldehyde, while oregano and carvacrol showed the least inhibition. Scanning electron microscopy images of S. Typhimurium on tomatoes suggest that the EOs and their major components damaged the bacteria, and the damage was more obvious after posttreatment storage at 10 °C for 4 and 7 d. Salmonella on inoculated tomatoes was reduced by more than 5 log colony forming units (CFU)/g by mustard EO and AIT, by 4.56 and 3.79 log CFU/g following cinnamon EO and cinnamaldehyde treatments, respectively, and 1.54 and 3.37 log CFU/g after oregano EO and carvacrol treatments, respectively. Mustard EO and AIT induced discoloration, softening, and loss of the vitamin C and lycopene during 21 d of storage at 10 °C, while treatment with cinnamon EO and cinnamaldehyde did not result in significant changes in tomato quality. Tomatoes treated with oregano EO had better quality than nontreated samples after storage. Therefore, treatment with cinnamon and oregano EO and their major components appeared to be feasible for inactivation of Salmonella on tomatoes and maintaining quality.
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Affiliation(s)
- Juan Yun
- Key Laboratory of Food Nutrition and Safety, Tianjin University of Science and Technology, Ministry of Education, Tianjin, P R China
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Barat S, Willer Y, Rizos K, Claudi B, Mazé A, Schemmer AK, Kirchhoff D, Schmidt A, Burton N, Bumann D. Immunity to intracellular Salmonella depends on surface-associated antigens. PLoS Pathog 2012; 8:e1002966. [PMID: 23093937 PMCID: PMC3475680 DOI: 10.1371/journal.ppat.1002966] [Citation(s) in RCA: 66] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2012] [Accepted: 08/14/2012] [Indexed: 01/05/2023] Open
Abstract
Invasive Salmonella infection is an important health problem that is worsening because of rising antimicrobial resistance and changing Salmonella serovar spectrum. Novel vaccines with broad serovar coverage are needed, but suitable protective antigens remain largely unknown. Here, we tested 37 broadly conserved Salmonella antigens in a mouse typhoid fever model, and identified antigen candidates that conferred partial protection against lethal disease. Antigen properties such as high in vivo abundance or immunodominance in convalescent individuals were not required for protectivity, but all promising antigen candidates were associated with the Salmonella surface. Surprisingly, this was not due to superior immunogenicity of surface antigens compared to internal antigens as had been suggested by previous studies and novel findings for CD4 T cell responses to model antigens. Confocal microscopy of infected tissues revealed that many live Salmonella resided alone in infected host macrophages with no damaged Salmonella releasing internal antigens in their vicinity. In the absence of accessible internal antigens, detection of these infected cells might require CD4 T cell recognition of Salmonella surface-associated antigens that could be processed and presented even from intact Salmonella. In conclusion, our findings might pave the way for development of an efficacious Salmonella vaccine with broad serovar coverage, and suggest a similar crucial role of surface antigens for immunity to both extracellular and intracellular pathogens. Salmonella infections cause extensive morbidity and mortality worldwide. A vaccine that prevents systemic Salmonella infections is urgently needed but suitable antigens remain largely unknown. In this study we identified several antigen candidates that mediated protective immunity to Salmonella in a mouse typhoid fever model. Interestingly, all these antigens were associated with the Salmonella surface. This suggested that similar antigen properties might be relevant for CD4 T cell dependent immunity to intracellular pathogens like Salmonella, as for antibody-dependent immunity to extracellular pathogens. Detailed analysis revealed that Salmonella surface antigens were not generally more immunogenic compared to internal antigens. However, internal antigens were inaccessible for CD4 T cell recognition of a substantial number of infected host cells that contained exclusively live intact Salmonella. Together, these results might pave the way for development of an efficacious Salmonella vaccine, and provide a basis to facilitate antigen identification for Salmonella and possibly other intracellular pathogens.
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Affiliation(s)
- Somedutta Barat
- Focal Area Infection Biology, Biozentrum, University of Basel, Basel, Switzerland
| | - Yvonne Willer
- Junior Group “Mucosal Infections”, Hannover Medical School, Hannover, Germany
| | - Konstantin Rizos
- Department of Molecular Biology, Max-Planck-Institute for Infection Biology, Berlin, Germany
| | - Beatrice Claudi
- Focal Area Infection Biology, Biozentrum, University of Basel, Basel, Switzerland
| | - Alain Mazé
- Focal Area Infection Biology, Biozentrum, University of Basel, Basel, Switzerland
| | - Anne K. Schemmer
- Focal Area Infection Biology, Biozentrum, University of Basel, Basel, Switzerland
| | - Dennis Kirchhoff
- Immunomodulation Group, Deutsches Rheuma-Forschungszentrum Berlin, Berlin, Germany
| | - Alexander Schmidt
- Proteomics Core Facility, Biozentrum, University of Basel, Basel, Switzerland
| | - Neil Burton
- Focal Area Infection Biology, Biozentrum, University of Basel, Basel, Switzerland
| | - Dirk Bumann
- Focal Area Infection Biology, Biozentrum, University of Basel, Basel, Switzerland
- Junior Group “Mucosal Infections”, Hannover Medical School, Hannover, Germany
- Department of Molecular Biology, Max-Planck-Institute for Infection Biology, Berlin, Germany
- * E-mail:
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Shin H, Lee JH, Kim H, Choi Y, Heu S, Ryu S. Receptor diversity and host interaction of bacteriophages infecting Salmonella enterica serovar Typhimurium. PLoS One 2012; 7:e43392. [PMID: 22927964 PMCID: PMC3424200 DOI: 10.1371/journal.pone.0043392] [Citation(s) in RCA: 80] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2012] [Accepted: 07/20/2012] [Indexed: 01/21/2023] Open
Abstract
BACKGROUND Salmonella enterica subspecies enterica serovar Typhimurium is a gram-negative pathogen causing salmonellosis. Salmonella Typhimurium-targeting bacteriophages have been proposed as an alternative biocontrol agent to antibiotics. To further understand infection and interaction mechanisms between the host strains and the bacteriophages, the receptor diversity of these phages needs to be elucidated. METHODOLOGY/PRINCIPAL FINDINGS Twenty-five Salmonella phages were isolated and their receptors were identified by screening a Tn5 random mutant library of S. Typhimurium SL1344. Among them, three types of receptors were identified flagella (11 phages), vitamin B(12) uptake outer membrane protein, BtuB (7 phages) and lipopolysaccharide-related O-antigen (7 phages). TEM observation revealed that the phages using flagella (group F) or BtuB (group B) as a receptor belong to Siphoviridae family, and the phages using O-antigen of LPS as a receptor (group L) belong to Podoviridae family. Interestingly, while some of group F phages (F-I) target FliC host receptor, others (F-II) target both FliC and FljB receptors, suggesting that two subgroups are present in group F phages. Cross-resistance assay of group B and L revealed that group L phages could not infect group B phage-resistant strains and reversely group B phages could not infect group L SPN9TCW-resistant strain. CONCLUSIONS/SIGNIFICANCE In this report, three receptor groups of 25 newly isolated S. Typhimurium-targeting phages were determined. Among them, two subgroups of group F phages interact with their host receptors in different manner. In addition, the host receptors of group B or group L SPN9TCW phages hinder other group phage infection, probably due to interaction between receptors of their groups. This study provides novel insights into phage-host receptor interaction for Salmonella phages and will inform development of optimal phage therapy for protection against Salmonella.
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Affiliation(s)
- Hakdong Shin
- Department of Food and Animal Biotechnology, Department of Agricultural Biotechnology and Center for Agricultural Biomaterials, Seoul National University, Seoul, Korea
| | - Ju-Hoon Lee
- Department of Food Science and Biotechnology, Kyung Hee University, Yongin, Korea
| | - Hyeryen Kim
- Department of Food and Animal Biotechnology, Department of Agricultural Biotechnology and Center for Agricultural Biomaterials, Seoul National University, Seoul, Korea
| | - Younho Choi
- Department of Food and Animal Biotechnology, Department of Agricultural Biotechnology and Center for Agricultural Biomaterials, Seoul National University, Seoul, Korea
| | - Sunggi Heu
- Microbial Safety Division, National Academy of Agricultural Science, Rural Development Administration, Suwon, Korea
| | - Sangryeol Ryu
- Department of Food and Animal Biotechnology, Department of Agricultural Biotechnology and Center for Agricultural Biomaterials, Seoul National University, Seoul, Korea
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Simple Deletion: a vector- and marker-free method to generate and isolate site-directed deletion mutants. Appl Microbiol Biotechnol 2012; 94:215-22. [PMID: 22391971 DOI: 10.1007/s00253-012-3964-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2011] [Revised: 02/06/2012] [Accepted: 02/10/2012] [Indexed: 10/28/2022]
Abstract
We have designed a new vector- and marker-free site-directed deletion system for gram-negative bacteria. In this system, a specific DNA fragment is amplified from a parental strain by using polymerase chain reaction (PCR), then circularized and introduced back into the parental strain for homologous recombination. The recombinant mutant is then detected and isolated by PCR-based sib selection. Unlike conventional methods, our Simple Deletion method requires no cloning procedures, and no foreign genes such as antibiotic-resistance genes are introduced as selection markers. The resulting mutant is, therefore, the same as the parental strain except for the lack of the target region. This method is categorized as a type of "self-cloning," and the resulting mutant can be used for laboratory research without restrictions. Using this method, we generated a mutant of a plant pathogenic bacterium, Xanthomonas campestris pv. campestris, in which the 20.4-kb hrp gene cluster involved in the type III secretion system and in pathogenicity was deleted. In addition, we proved that this method can also be used to delete smaller DNA regions of X. campestris pv. campestris and to generate deletion mutants of the bacterium Ralstonia solanacearum.
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Park M, Lee JH, Shin H, Kim M, Choi J, Kang DH, Heu S, Ryu S. Characterization and comparative genomic analysis of a novel bacteriophage, SFP10, simultaneously inhibiting both Salmonella enterica and Escherichia coli O157:H7. Appl Environ Microbiol 2012; 78:58-69. [PMID: 22020516 PMCID: PMC3255626 DOI: 10.1128/aem.06231-11] [Citation(s) in RCA: 134] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2011] [Accepted: 10/07/2011] [Indexed: 11/20/2022] Open
Abstract
Salmonella enterica and Escherichia coli O157:H7 are major food-borne pathogens causing serious illness. Phage SFP10, which revealed effective infection of both S. enterica and E. coli O157:H7, was isolated and characterized. SFP10 contains a 158-kb double-stranded DNA genome belonging to the Vi01 phage-like family Myoviridae. In vitro adsorption assays showed that the adsorption constant rates to both Salmonella enterica serovar Typhimurium and E. coli O157:H7 were 2.50 × 10⁻⁸ ml/min and 1.91 × 10⁻⁸ ml/min, respectively. One-step growth analysis revealed that SFP10 has a shorter latent period (25 min) and a larger burst size (>200 PFU) than ordinary Myoviridae phages, suggesting effective host infection and lytic activity. However, differential development of resistance to SFP10 in S. Typhimurium and E. coli O157:H7 was observed; bacteriophage-insensitive mutant (BIM) frequencies of 1.19 × 10⁻² CFU/ml for S. Typhimurium and 4.58 × 10⁻⁵ CFU/ml for E. coli O157:H7 were found, indicating that SFP10 should be active and stable for control of E. coli O157:H7 with minimal emergence of SFP10-resistant pathogens but may not be for S. Typhimurium. Specific mutation of rfaL in S. Typhimurium and E. coli O157:H7 revealed the O antigen as an SFP10 receptor for both bacteria. Genome sequence analysis of SFP10 and its comparative analysis with homologous Salmonella Vi01 and Shigella phiSboM-AG3 phages revealed that their tail fiber and tail spike genes share low sequence identity, implying that the genes are major host specificity determinants. This is the first report identifying specific infection and inhibition of Salmonella Typhimurium and E. coli O157:H7 by a single bacteriophage.
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Affiliation(s)
- Minjung Park
- Department of Food and Animal Biotechnology, Department of Agricultural Biotechnology, Research Institute for Agriculture and Life Sciences, and Center for Agricultural Biomaterials, Seoul National University, Seoul, South Korea
| | - Ju-Hoon Lee
- Laboratory of Food Microbiology and Functional Genomics, Department of Food Science and Biotechnology, CHA University, Seongnam, South Korea
| | - Hakdong Shin
- Department of Food and Animal Biotechnology, Department of Agricultural Biotechnology, Research Institute for Agriculture and Life Sciences, and Center for Agricultural Biomaterials, Seoul National University, Seoul, South Korea
| | - Minsik Kim
- Department of Food and Animal Biotechnology, Department of Agricultural Biotechnology, Research Institute for Agriculture and Life Sciences, and Center for Agricultural Biomaterials, Seoul National University, Seoul, South Korea
| | - Jeongjoon Choi
- Department of Food and Animal Biotechnology, Department of Agricultural Biotechnology, Research Institute for Agriculture and Life Sciences, and Center for Agricultural Biomaterials, Seoul National University, Seoul, South Korea
| | - Dong-Hyun Kang
- Department of Food and Animal Biotechnology, Department of Agricultural Biotechnology, Research Institute for Agriculture and Life Sciences, and Center for Agricultural Biomaterials, Seoul National University, Seoul, South Korea
| | - Sunggi Heu
- Microbial Safety Division, National Academy of Agricultural Science, Rural Development Administration, Suwon, South Korea
| | - Sangryeol Ryu
- Department of Food and Animal Biotechnology, Department of Agricultural Biotechnology, Research Institute for Agriculture and Life Sciences, and Center for Agricultural Biomaterials, Seoul National University, Seoul, South Korea
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Baek CH, Kang HY, Roland KL, Curtiss R. Lrp acts as both a positive and negative regulator for type 1 fimbriae production in Salmonella enterica serovar Typhimurium. PLoS One 2011; 6:e26896. [PMID: 22046399 PMCID: PMC3203922 DOI: 10.1371/journal.pone.0026896] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2011] [Accepted: 10/05/2011] [Indexed: 12/16/2022] Open
Abstract
Leucine-responsive regulatory protein (Lrp) is known to be an indirect activator of type 1 fimbriae synthesis in Salmonella enterica serovar Typhimurium via direct regulation of FimZ, a direct positive regulator for type 1 fimbriae production. Using RT-PCR, we have shown previously that fimA transcription is dramatically impaired in both lrp-deletion (Δlrp) and constitutive-lrp expression (lrpC) mutant strains. In this work, we used chromosomal PfimA-lacZ fusions and yeast agglutination assays to confirm and extend our previous results. Direct binding of Lrp to PfimA was shown by an electrophoretic mobility shift assay (EMSA) and DNA footprinting assay. Site-directed mutagenesis revealed that the Lrp-binding motifs in PfimA play a role in both activation and repression of type 1 fimbriae production. Overproduction of Lrp also abrogates fimZ expression. EMSA data showed that Lrp and FimZ proteins independently bind to PfimA without competitive exclusion. In addition, both Lrp and FimZ binding to PfimA caused a hyper retardation (supershift) of the DNA-protein complex compared to the shift when each protein was present alone. Nutrition-dependent cellular Lrp levels closely correlated with the amount of type 1 fimbriae production. These observations suggest that Lrp plays important roles in type 1 fimbriation by acting as both a positive and negative regulator and its effect depends, at least in part, on the cellular concentration of Lrp in response to the nutritional environment.
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Affiliation(s)
- Chang-Ho Baek
- The Biodesign Institute at Arizona State University, Tempe, Arizona, United States of America
| | - Ho-Young Kang
- Department of Microbiology, Pusan National University, Pusan, Korea
| | - Kenneth L. Roland
- The Biodesign Institute at Arizona State University, Tempe, Arizona, United States of America
| | - Roy Curtiss
- The Biodesign Institute at Arizona State University, Tempe, Arizona, United States of America
- School of Life Sciences at Arizona State University, Tempe, Arizona, United States of America
- * E-mail:
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Engineering and preclinical evaluation of attenuated nontyphoidal Salmonella strains serving as live oral vaccines and as reagent strains. Infect Immun 2011; 79:4175-85. [PMID: 21807911 DOI: 10.1128/iai.05278-11] [Citation(s) in RCA: 74] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
While nontyphoidal Salmonella (NTS) has long been recognized as a cause of self-limited gastroenteritis, it is becoming increasingly evident that multiple-antibiotic-resistant strains are also emerging as important causes of invasive bacteremia and focal infections, resulting in hospitalizations and deaths. We have constructed attenuated Salmonella enterica serovar Typhimurium and Salmonella enterica serovar Enteritidis strains that can serve as live oral vaccines and as "reagent strains" for subunit vaccine production in a safe and economical manner. Prototype attenuated vaccine strains CVD 1921 and CVD 1941, derived from the invasive wild-type strains S. Typhimurium I77 and S. Enteritidis R11, respectively, were constructed by deleting guaBA, encoding guanine biosynthesis, and clpP, encoding a master protease regulator. The clpP mutation resulted in a hyperflagellation phenotype. An additional deletion in fliD yielded reagent strains CVD 1923 and CVD 1943, respectively, which export flagellin monomers. Oral 50% lethal dose (LD₅₀) analyses showed that the NTS vaccine strains were all highly attenuated in mice. Oral immunization with CVD 1921 or CVD 1923 protected mice against lethal challenge with wild-type S. Typhimurium I77. Immunization with CVD 1941 but not CVD 1943 protected mice against lethal infection with S. Enteritidis R11. Immune responses induced by these strains included high levels of serum IgG anti-lipopolysaccharide (LPS) and anti-flagellum antibodies, with titers increasing progressively during the immunization schedule. Since S. Typhimurium and S. Enteritidis are the most common NTS serovars associated with invasive disease, these findings can pave the way for development of a highly effective, broad-spectrum vaccine against invasive NTS.
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Simon R, Tennant SM, Galen JE, Levine MM. Mouse models to assess the efficacy of non-typhoidal Salmonella vaccines: revisiting the role of host innate susceptibility and routes of challenge. Vaccine 2011; 29:5094-106. [PMID: 21616112 DOI: 10.1016/j.vaccine.2011.05.022] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2011] [Revised: 04/22/2011] [Accepted: 05/09/2011] [Indexed: 01/24/2023]
Abstract
Non-typhoidal Salmonella enterica (NTS) serovars Typhimurium and Enteritidis are important causes of bacterial gastroenteritis in the USA and worldwide. In sub-Saharan Africa these two serovars are emerging as agents associated with lethal invasive disease (e.g., bacteremia, meningitis). The development of NTS vaccines, based on mucosally administered live attenuated strains and parenteral non-living antigens, could diminish the NTS disease burden globally. Mouse models of S. Typhimurium and S. Enteritidis invasive disease can accelerate the development of NTS vaccines. Live attenuated NTS vaccines elicit both cellular and humoral immunity in mice and their efficacy is well established. In contrast, non-living vaccines that primarily elicit humoral immunity have demonstrated variable efficacy. An analysis of the reported studies with non-living vaccines against S. Typhimurium and S. Enteritidis reveals that efficacy is influenced by two important independent variables: (1) the innate susceptibility to NTS infection that differs dramatically between commonly used mouse strains and (2) the virulence of the NTS strain used for challenge. Protection by non-living vaccines has generally been seen only in host-pathogen interactions where a sub-lethal infection results, such as challenging resistant mice with either highly virulent or weakly virulent strains or susceptible mice with weakly virulent strains. The immunologic basis of this discrepancy and the implications for human NTS vaccine development are reviewed herein.
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Affiliation(s)
- Raphael Simon
- Center for Vaccine Development, University of Maryland School of Medicine, Baltimore, MD, 21201, USA.
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Zhang X, Wanda SY, Brenneman K, Kong W, Zhang X, Roland K, Curtiss R. Improving Salmonella vector with rec mutation to stabilize the DNA cargoes. BMC Microbiol 2011; 11:31. [PMID: 21303535 PMCID: PMC3047425 DOI: 10.1186/1471-2180-11-31] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2010] [Accepted: 02/08/2011] [Indexed: 01/16/2023] Open
Abstract
BACKGROUND Salmonella has been employed to deliver therapeutic molecules against cancer and infectious diseases. As the carrier for target gene(s), the cargo plasmid should be stable in the bacterial vector. Plasmid recombination has been reduced in E. coli by mutating several genes including the recA, recE, recF and recJ. However, to our knowledge, there have been no published studies of the effect of these or any other genes that play a role in plasmid recombination in Salmonella enterica. RESULTS The effect of recA, recF and recJ deletions on DNA recombination was examined in three serotypes of Salmonella enterica. We found that (1) intraplasmid recombination between direct duplications was RecF-independent in Typhimurium and Paratyphi A, but could be significantly reduced in Typhi by a ΔrecA or ΔrecF mutation; (2) in all three Salmonella serotypes, both ΔrecA and ΔrecF mutations reduced intraplasmid recombination when a 1041 bp intervening sequence was present between the duplications; (3) ΔrecA and ΔrecF mutations resulted in lower frequencies of interplasmid recombination in Typhimurium and Paratyphi A, but not in Typhi; (4) in some cases, a ΔrecJ mutation could reduce plasmid recombination but was less effective than ΔrecA and ΔrecF mutations. We also examined chromosome-related recombination. The frequencies of intrachromosomal recombination and plasmid integration into the chromosome were 2 and 3 logs lower than plasmid recombination frequencies in Rec+ strains. A ΔrecA mutation reduced both intrachromosomal recombination and plasmid integration frequencies. CONCLUSIONS The ΔrecA and ΔrecF mutations can reduce plasmid recombination frequencies in Salmonella enterica, but the effect can vary between serovars. This information will be useful for developing Salmonella delivery vectors able to stably maintain plasmid cargoes for vaccine development and gene therapy.
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Affiliation(s)
- Xiangmin Zhang
- The Biodesign Institute, Arizona State University, Tempe, AZ 85287, USA
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Immunological responses induced by asd and wzy/asd mutant strains of Salmonella enterica serovar Typhimurium in BALB/c mice. J Microbiol 2010; 48:486-95. [PMID: 20799091 DOI: 10.1007/s12275-010-0023-z] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2010] [Accepted: 03/17/2010] [Indexed: 12/27/2022]
Abstract
Attenuated bacteria have long been developed as vaccine candidates but can have some disadvantages, such as the potential for damage to immune organs due to insufficient clearance. To minimize these disadvantages, we generated Salmonella enterica serovar Typhimurium mutants SHJ2104 (asd::cm) and HTSaYA (wzy::km, asd::cm). The wzy gene codes for the O-antigen polymerase, which is involved in lipopolysaccharide (LPS) biosynthesis, and asd codes for aspartate beta-semialdehyde dehydrogenase, which participates in cell wall formation. The strains synthesized LPS with a short-chain length, and showed lower cytotoxicity and reduced intracellular proliferation in animal cells compared to wild-type bacteria. After oral infection, the mutants were cleared in immune tissues, including the Peyer's patch, mesenteric lymph node, and spleen, within 5 days. The LD50 of the mutants in Balb/c mice was estimated to be 10(6) higher than wild-type bacteria when administered either via an oral or i.p. route, indicating that the two strains are highly attenuated. To compare the immune response to and protective effects of the mutants against wild-type bacterial infection, we inoculated the mutants into mice via an oral (1x10(10)CFU) or i.p. (1x10(7) CFU) route once or twice at a two week interval. All immune responses, such as serum IgG and secretory IgA levels, cytokine production, and delayed hypersensitivity, were highly induced by two rounds of immunization. HTSaYA and SHJ2104 induced similar immune responses, and mice immunized with HTSaYA or SHJ2104 via an i.p. route were protected against wild-type Salmonella infection even at 100-fold of the LD(50) (5x10(6) CFU). Taken together, these data indicate that HTSaYA and SHJ2104 could be developed as live attenuated Salmonella vaccine candidates.
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Ameiss K, Ashraf S, Kong W, Pekosz A, Wu WH, Milich D, Billaud JN, Curtiss R. Delivery of woodchuck hepatitis virus-like particle presented influenza M2e by recombinant attenuated Salmonella displaying a delayed lysis phenotype. Vaccine 2010; 28:6704-13. [PMID: 20691653 DOI: 10.1016/j.vaccine.2010.07.083] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2010] [Revised: 07/27/2010] [Accepted: 07/28/2010] [Indexed: 02/02/2023]
Abstract
The use of live recombinant attenuated Salmonella vaccines (RASV) is a promising approach for controlling infections by multiple pathogens. The highly conserved extracellular domain of the influenza M2 protein (M2e) has been shown to provide broad spectrum protection against multiple influenza subtypes sharing similar M2e sequences. An M2e epitope common to a number of avian influenza subtypes was inserted into the core antigen of woodchuck hepatitis virus and expressed in two different recombinant attenuated Salmonella Typhimurium strains. One strain was attenuated via deletion of the cya and crp genes. The second strain was engineered to exhibit a programmed delayed lysis phenotype. Both strains were able to produce both monomeric fusion proteins and fully assembled core particles. Mice orally immunized with the strain exhibiting delayed lysis induced significantly greater antibody titers than the Δcya Δcrp strain and provided moderate protection against weight loss to a low level challenge with the influenza strain A/WSN/33 modified to express the M2e sequence common to avian viruses. Further studies indicated that the Salmonella expressed core antigen induced comparable antibody levels to the purified core antigen injected with an alum adjuvant and that both are able to reduce viral replication in the lungs. To our knowledge this is the first report demonstrating Salmonella-mediated delivery of influenza virus M2e protein in a mammalian host to induce a protective immune response against viral challenge.
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Affiliation(s)
- Keith Ameiss
- The Biodesign Institute, Center for Infectious Diseases and Vaccinology, Arizona State University, Tempe, AZ 85287, USA
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Choi J, Shin D, Ryu S. Salmonella enterica serovar Typhimurium ruvB mutant can confer protection against salmonellosis in mice. Vaccine 2010; 28:6436-44. [PMID: 20670908 DOI: 10.1016/j.vaccine.2010.07.048] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2010] [Revised: 07/13/2010] [Accepted: 07/15/2010] [Indexed: 12/29/2022]
Abstract
Salmonella enterica is an important pathogen that causes a variety of infectious diseases in animals and humans. Live attenuated vaccines generally confer better protection than killed or subunit vaccines; however, the former are limited by their inherent toxicity. We evaluated the potential of a novel candidate Salmonella vaccine strain that lacks the ruvB gene. The ruvB gene encodes a Holliday junction helicase that is required to resolve junctions that arise during the repair of non-arresting lesions after DNA replication. The deletion of this gene in Salmonella significantly impaired cell survival and proliferation within epithelial cells and macrophages. The defective virulence in ruvB mutant may be partially due to decreased expression of ssaG, a Salmonella pathogenicity island-2 gene, and increased sensitivity to hydrogen peroxide in the lack of ruvB gene. The virulence of the ruvB-deleted mutant was also greatly attenuated in BALB/c mice. The ruvB mutant conferred strong and durable immune-based protection against a challenge with a lethal dose of a virulent strain of Salmonella Typhimurium. Moreover, protective immunity was induced by a single dose of the vaccine, and the efficacy of protection was maintained for at least 6 months. These results suggest the use of the S. Typhimurium ruvB mutant as a novel vaccine.
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Affiliation(s)
- Jeongjoon Choi
- Department of Food and Animal Biotechnology, Department of Agricultural Biotechnology, Center for Agricultural Biomaterials, and Research Institute for Agriculture and Life Sciences, Seoul National University, Seoul 151-921, Republic of Korea
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Construction of recombinant attenuated Salmonella enterica serovar typhimurium vaccine vector strains for safety in newborn and infant mice. CLINICAL AND VACCINE IMMUNOLOGY : CVI 2010; 17:354-62. [PMID: 20053874 DOI: 10.1128/cvi.00412-09] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Recombinant bacterial vaccines must be safe, efficacious, and well tolerated, especially when administered to newborns and infants to prevent diseases of early childhood. Many means of attenuation have been shown to render vaccine strains susceptible to host defenses or unable to colonize lymphoid tissue effectively, thus decreasing their immunogenicity. We have constructed recombinant attenuated Salmonella vaccine strains that display high levels of attenuation while retaining the ability to induce high levels of immunogenicity and are well tolerated in high doses when administered to infant mice as young as 24 h old. The strains contain three means of regulated delayed attenuation, as well as a constellation of additional mutations that aid in enhancing safety, regulate antigen expression, and reduce disease symptoms commonly associated with Salmonella infection. The vaccine strains are well tolerated when orally administered to infant mice 24 h old at doses as high as 3.5 x 10(8) CFU.
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Kotarsky K, Sitnik KM, Stenstad H, Kotarsky H, Schmidtchen A, Koslowski M, Wehkamp J, Agace WW. A novel role for constitutively expressed epithelial-derived chemokines as antibacterial peptides in the intestinal mucosa. Mucosal Immunol 2010; 3:40-8. [PMID: 19812544 DOI: 10.1038/mi.2009.115] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Intestinal-derived chemokines have a central role in orchestrating immune cell influx into the normal and inflamed intestine. Here, we identify the chemokine CCL6 as one of the most abundant chemokines constitutively expressed by both murine small intestinal and colonic epithelial cells. CCL6 protein localized to crypt epithelial cells, was detected in the gut lumen and reached high concentrations at the mucosal surface. Its expression was further enhanced in the small intestine following in vivo administration of LPS or after stimulation of the small intestinal epithelial cell line, mIC(c12), with IFNgamma, IL-4 or TNFalpha. Recombinant- and intestinal-derived CCL6 bound to a subset of the intestinal microflora and displayed antibacterial activity. Finally, the human homologs to CCL6, CCL14 and CCL15 were also constitutively expressed at high levels in human intestinal epithelium, were further enhanced in inflammatory bowel disease and displayed similar antibacterial activity. These findings identify a novel role for constitutively expressed, epithelial-derived chemokines as antimicrobial peptides in the intestinal mucosa.
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Affiliation(s)
- K Kotarsky
- Immunology Section, Department of Experimental Medical Sciences, Lund University, Lund, Sweden.
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Chen ZW, Hsuan SL, Liao JW, Chen TH, Wu CM, Lee WC, Lin CC, Liao CM, Yeh KS, Winton JR, Huang C, Chien MS. Mutations in the Salmonella enterica serovar Choleraesuis cAMP-receptor protein gene lead to functional defects in the SPI-1 Type III secretion system. Vet Res 2009; 41:5. [PMID: 19775595 PMCID: PMC2769549 DOI: 10.1051/vetres/2009053] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2009] [Accepted: 09/18/2009] [Indexed: 12/30/2022] Open
Abstract
Salmonella enterica serovar Choleraesuis (Salmonella Choleraesuis) causes a lethal systemic infection (salmonellosis) in swine. Live attenuated Salmonella Choleraesuis vaccines are effective in preventing the disease, and isolates of Salmonella Choleraesuis with mutations in the cAMP-receptor protein (CRP) gene (Salmonella Choleraesuis ∆crp) are the most widely used, although the basis of the attenuation remains unclear. The objective of this study was to determine if the attenuated phenotype of Salmonella Choleraesuis ∆crp was due to alterations in susceptibility to gastrointestinal factors such as pH and bile salts, ability to colonize or invade the intestine, or cytotoxicity for macrophages. Compared with the parental strain, the survival rate of Salmonella Choleraesuis ∆crp at low pH or in the presence of bile salts was higher, while the ability of the mutant to invade intestinal epithelia was significantly decreased. In examining the role of CRP on the secretory function of the Salmonella pathogenicity island 1 (SPI-1) encoded type III secretion system (T3SS), it was shown that Salmonella Choleraesuis ∆crp was unable to secrete the SPI-1 T3SS effector proteins, SopB and SipB, which play a role in Salmonella intestinal invasiveness and macrophage cytotoxicity, respectively. In addition, caspase-1 dependent cytotoxicity for macrophages was significantly reduced in Salmonella Choleraesuis ∆crp. Collectively, this study demonstrates that the CRP affects the secretory function of SPI-1 T3SS and the resulting ability to invade the host intestinal epithelium, which is a critical element in the pathogenesis of Salmonella Choleraesuis.
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Affiliation(s)
- Zeng-Weng Chen
- Graduate Institute of Veterinary Pathobiology, College of Veterinary Medicine, National Chung Hsing University, 250 Kuo Kuang Road, Taichung 402, Taiwan, Republic of China
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Leucine-responsive regulatory protein (Lrp) acts as a virulence repressor in Salmonella enterica serovar Typhimurium. J Bacteriol 2008; 191:1278-92. [PMID: 19074398 DOI: 10.1128/jb.01142-08] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Leucine-responsive regulatory protein (Lrp) is a global gene regulator that influences expression of a large number of genes including virulence-related genes in Escherichia coli and Salmonella. No systematic studies examining the regulation of virulence genes by Lrp have been reported in Salmonella. We report here that constitutive expression of Lrp [lrp(Con)] dramatically attenuates Salmonella virulence while an lrp deletion (Deltalrp) mutation enhances virulence. The lrp(Con) mutant caused pleiotropic effects that include defects in invasion, cytotoxicity, and colonization, whereas the Deltalrp mutant was more proficient at these activities than the wild-type strain. We present evidence that Lrp represses transcription of key virulence regulator genes--hilA, invF, and ssrA--in Salmonella pathogenicity island 1 (SPI-1) and 2 (SPI-2), by binding directly to their promoter regions, P(hilA), P(invF), and P(ssrA). In addition, Western blot analysis showed that the expression of the SPI-1 effector SipA was reduced in the lrp(Con) mutant and enhanced in the Deltalrp mutant. Computational analysis revealed putative Lrp-binding consensus DNA motifs located in P(hilA), P(invF), and P(ssrA). These results suggest that Lrp binds to the consensus motifs and modulates expression of the linked genes. The presence of leucine enhanced Lrp binding to P(invF) in vitro and the addition of leucine to growth medium decreased the level of invF transcription. However, leucine had no effect on expression of hilA and ssrA or on cellular levels of Lrp. In addition, Lrp appears to be an antivirulence gene, since the deletion mutant showed enhanced cell invasion, cytotoxicity, and hypervirulence in BALB/c mice.
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Regulated programmed lysis of recombinant Salmonella in host tissues to release protective antigens and confer biological containment. Proc Natl Acad Sci U S A 2008; 105:9361-6. [PMID: 18607005 DOI: 10.1073/pnas.0803801105] [Citation(s) in RCA: 108] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
We have devised and constructed a biological containment system designed to cause programmed bacterial cell lysis with no survivors. We have validated this system, using Salmonella enterica serovar Typhimurium vaccines for antigen delivery after colonization of host lymphoid tissues. The system is composed of two parts. The first component is Salmonella typhimurium strain chi8937, with deletions of asdA and arabinose-regulated expression of murA, two genes required for peptidoglycan synthesis and additional mutations to enhance complete lysis and antigen delivery. The second component is plasmid pYA3681, which encodes arabinose-regulated murA and asdA expression and C2-regulated synthesis of antisense asdA and murA mRNA transcribed from the P22 P(R) promoter. An arabinose-regulated c2 gene is present in the chromosome. chi8937(pYA3681) exhibits arabinose-dependent growth. Upon invasion of host tissues, an arabinose-free environment, transcription of asdA, murA, and c2 ceases, and concentrations of their gene products decrease because of cell division. The drop in C2 concentration results in activation of P(R), driving synthesis of antisense mRNA to block translation of any residual asdA and murA mRNA. A highly antigenic alpha-helical domain of Streptococcus pneumoniae Rx1 PspA was cloned into pYA3681, resulting in pYA3685 to test antigen delivery. Mice orally immunized with chi8937(pYA3685) developed antibody responses to PspA and Salmonella outer membrane proteins. No viable vaccine strain cells were detected in host tissues after 21 days. This system has potential applications with other Gram-negative bacteria in which biological containment would be desirable.
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Analysis of type II secretion of recombinant pneumococcal PspA and PspC in a Salmonella enterica serovar Typhimurium vaccine with regulated delayed antigen synthesis. Infect Immun 2008; 76:3241-54. [PMID: 18458067 DOI: 10.1128/iai.01623-07] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Recombinant attenuated Salmonella vaccines (RASVs) have been used extensively to express and deliver heterologous antigens to host mucosal tissues. Immune responses can be enhanced greatly when the antigen is secreted to the periplasm or extracellular compartment. The most common method for accomplishing this is by fusion of the antigen to a secretion signal sequence. Finding an optimal signal sequence is typically done empirically. To facilitate this process, we constructed a series of plasmid expression vectors, each containing a different type II signal sequence. We evaluated the utilities of these vectors by fusing two different antigens, the alpha-helix domains of pneumococcal surface protein A (PspA) and pneumococcal surface protein C (PspC), to the signal sequences of beta-lactamase (bla SS), ompA, and phoA and the signal sequence and C-terminal peptide of beta-lactamase (bla SS+CT) on Asd(+) plasmids under the control of the P(trc) promoter. Strains were characterized for level of expression, subcellular antigen location, and the capacity to elicit antigen-specific immune responses and protection against challenge with Streptococcus pneumoniae in mice. The immune responses to each protein differed depending on the signal sequence used. Strains carrying the bla SS-pspA and bla SS+CT-pspC fusions yielded the largest amounts of secreted PspA and PspC, respectively, and induced the highest serum IgG titers, although all fusion proteins tested induced some level of antigen-specific IgG response. Consistent with the serum antibody responses, RASVs expressing the bla SS-pspA and bla SS+CT-pspC fusions induced the greatest protection against S. pneumoniae challenge.
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Liu T, König R, Sha J, Agar SL, Tseng CTK, Klimpel GR, Chopra AK. Immunological responses against Salmonella enterica serovar Typhimurium Braun lipoprotein and lipid A mutant strains in Swiss-Webster mice: potential use as live-attenuated vaccines. Microb Pathog 2007; 44:224-37. [PMID: 17997275 DOI: 10.1016/j.micpath.2007.09.005] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2007] [Revised: 09/19/2007] [Accepted: 09/21/2007] [Indexed: 10/22/2022]
Abstract
We generated and characterized Salmonella enterica serovar Typhimurium mutants that were deleted for the genes encoding Braun lipoprotein (lpp) alone or in conjunction with the msbB gene, which codes for an enzyme required for the acylation of the lipid A moiety of lipopolysaccharide. Two copies of the lpp gene, designated as lppA and lppB, exist on the chromosome of S. Typhimurium. These mutants were highly attenuated in a mouse infection model and induced minimal histopathological changes in mouse organs compared to those seen in infection with wild-type (WT) S. Typhimurium. The lppB/msbB and the lppAB/msbB mutants were maximally attenuated, and hence further examined in this study for their ability to induce humoral and cellular immune responses. Importantly, infection of out-bred Swiss-Webster mice with the mutant S. Typhimurium generated superior T helper cell type 2 (Th2) responses compared to WT S. Typhimurium, as determined by measuring IgG subclasses and cytokines. WT S. Typhimurium induced higher levels of IgG2a in sera of infected mice, while the lppB/msbB and lppAB/msbB mutants mounted higher levels of IgG1 as determined by an enzyme-linked immunosorbent assay. Mice immunized with lppB/msbB and lppAB/msbB mutants rapidly cleared WT S. Typhimurium upon subsequent rechallenge, and naïve mice passively immunized with sera from animals infected with S. Typhimurium mutants were protected against subsequent challenge with WT S. Typhimurium. Splenic T cells produced higher levels of interferon-gamma following ex vivo exposure to WT S. Typhimurium, while splenic T cells infected with the above-mentioned two mutants evoked higher levels of interleukin-6. Further, mice infected with lppB/msbB and lppAB/msbB mutants showed much higher levels of splenic T cell activation as measured by CD44(+) expression on CD4(+) T cells by flow cytometry and by incorporation of (3)H-thymidine compared to mice that were infected with WT S. Typhimurium. We expect the lppB/msbB and lppAB/msbB mutants to be excellent live-attenuated vaccine candidates, because they induced minimal inflammatory responses and evoked stronger and specific antibody and cellular immune responses.
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Affiliation(s)
- Tie Liu
- Department of Microbiology and Immunology, University of Texas Medical Branch, 301 University Blvd., Galveston, TX 775551070, USA
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Rosu V, Chadfield MS, Santona A, Christensen JP, Thomsen LE, Rubino S, Olsen JE. Effects of crp deletion in Salmonella enterica serotype Gallinarum. Acta Vet Scand 2007; 49:14. [PMID: 17488512 PMCID: PMC1885444 DOI: 10.1186/1751-0147-49-14] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2006] [Accepted: 05/08/2007] [Indexed: 11/10/2022] Open
Abstract
Background Salmonella enterica serotype Gallinarum (S. Gallinarum) remains an important pathogen of poultry, especially in developing countries. There is a need to develop effective and safe vaccines. In the current study, the effect of crp deletion was investigated with respect to virulence and biochemical properties and the possible use of a deletion mutant as vaccine candidate was preliminarily tested. Methods Mutants were constructed in S. Gallinarum by P22 transduction from Salmonella Typhimurium (S. Typhimurium) with deletion of the crp gene. The effect was characterized by measuring biochemical properties and by testing of invasion in a chicken loop model and by challenge of six-day-old chickens. Further, birds were immunized with the deleted strain and challenged with the wild type isolate. Results The crp deletions caused complete attenuation of S. Gallinarum. This was shown by ileal loop experiments not to be due to significantly reduced invasion. Strains with such deletions may have vaccine potential, since oral inoculatoin with S. Gallinarum Δcrp completely protected against challenge with the same dose of wild type S. Gallinarum ten days post immunization. Interestingly, the mutations did not cause the same biochemical and growth changes to the two biotypes of S. Gallinarum. All biochemical effects but not virulence could be complemented by providing an intact crp-gene from S. Typhimurium on the plasmid pSD110. Conclusion Transduction of a Tn10 disrupted crp gene from S. Typhimurium caused attenuation in S. Gallinarum and mutated strains are possible candidates for live vaccines against fowl typhoid.
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Ledeboer NA, Frye JG, McClelland M, Jones BD. Salmonella enterica serovar Typhimurium requires the Lpf, Pef, and Tafi fimbriae for biofilm formation on HEp-2 tissue culture cells and chicken intestinal epithelium. Infect Immun 2006; 74:3156-69. [PMID: 16714543 PMCID: PMC1479237 DOI: 10.1128/iai.01428-05] [Citation(s) in RCA: 116] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2005] [Revised: 01/03/2006] [Accepted: 02/22/2006] [Indexed: 01/08/2023] Open
Abstract
Recent work has demonstrated that Salmonella enterica serovar Typhimurium forms biofilms on HEp-2 tissue culture cells in a type 1 fimbria-dependent manner. To investigate how biofilm growth of HEp-2 tissue culture cells affects gene expression in Salmonella, we compared global gene expression during planktonic growth and biofilm growth. Microarray results indicated that the transcription of approximately 100 genes was substantially altered by growth in a biofilm. These genes encode proteins with a wide range of functions, including antibiotic resistance, central metabolism, conjugation, intracellular survival, membrane transport, regulation, and fimbrial biosynthesis. The identification of five fimbrial gene clusters was of particular interest, as we have demonstrated that type 1 fimbriae are required for biofilm formation on HEp-2 cells and murine intestinal epithelium. Mutations in each of these fimbriae were constructed in S. enterica serovar Typhimurium strain BJ2710, and the mutants were found to have various biofilm phenotypes on plastic, HEp-2 cells, and chicken intestinal tissue. The pef and csg mutants were defective for biofilm formation on each of the three surfaces tested, while the lpf mutant exhibited a complete loss of the ability to form a biofilm on chicken intestinal tissue but only an intermediate loss of the ability to form a biofilm on tissue culture cells and plastic surfaces. The bcf mutant displayed increased biofilm formation on both HEp-2 cells and chicken intestinal epithelium, while the sth mutant had no detectable biofilm defects. In all instances, the mutants could be restored to a wild-type phenotype by a plasmid carrying the functional genes. This is the first work to identify the genomic responses of Salmonella to biofilm formation on host cells, and this work highlights the importance of fimbriae in adhering to and adapting to a eukaryotic cell surface. An understanding of these interactions is likely to provide new insights for intervention strategies in Salmonella colonization and infection.
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Affiliation(s)
- Nathan A Ledeboer
- Department of Microbiology, Roy J. and Lucille A. Carver School of Medicine, University of Iowa, Iowa City, IA 52242-1109.
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Tatum FM, Briggs RE. Construction of in-frame aroA deletion mutants of Mannheimia haemolytica, Pasteurella multocida, and Haemophilus somnus by using a new temperature-sensitive plasmid. Appl Environ Microbiol 2005; 71:7196-202. [PMID: 16269759 PMCID: PMC1287724 DOI: 10.1128/aem.71.11.7196-7202.2005] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
A temperature-sensitive (TS) plasmid was generated from the endogenous streptomycin resistance plasmid of Mannheimia hemolytica and used to engineer in-frame aroA deletion mutants of Mannheimia hemolytica, Pasteurella multocida, and Haemophilus somnus. TS replacement plasmids carrying in-frame aroA deletions were constructed for each target species and introduced into host cells by electroporation. After recovery in broth, cells were spread onto plates containing antibiotic and incubated at 30 degrees C, the permissive temperature for autonomous plasmid replication. Transfer of transformants to selective plates cultured at a nonpermissive temperature for plasmid replication selected for single-crossover mutants consisting of replacement plasmids that had integrated into host chromosomes by homologous recombination. Transfer of the single-crossover mutants back to a permissive temperature without antibiotic selection drove plasmid resolution, and, depending on where plasmid excision occurred, either deletion mutants or wild-type cells were generated. The system used here represents a broadly applicable means for generating unmarked mutants of Pasteurellaceae species.
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Affiliation(s)
- Fred M Tatum
- National Animal Disease Center, Agricultural Research Service, U.S. Department of Agriculture, Ames, IA 50010, USA.
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Na HS, Kim HJ, Lee HC, Hong Y, Rhee JH, Choy HE. Immune response induced by Salmonella typhimurium defective in ppGpp synthesis. Vaccine 2005; 24:2027-34. [PMID: 16356600 DOI: 10.1016/j.vaccine.2005.11.031] [Citation(s) in RCA: 80] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2005] [Revised: 11/09/2005] [Accepted: 11/15/2005] [Indexed: 11/24/2022]
Abstract
Systemic infection by Salmonella typhimurium requires coordinated expression of virulence genes found primarily in Salmonella Pathogenecity Islands (SPIs). We have previously reported that the intracellular signal that induces these virulence genes is a stringent signal molecule, ppGpp [Song et al. J Biol Chem 2003;279:34183]. In this study, we found that relA and spoT double mutant Salmonella (DeltappGpp strain), which is defective in ppGpp synthesis, was virtually avirulent in BALB/c mice. Subsequently, the live vaccine potential of the avirulent DeltappGpp Salmonella strain was determined. A single immunization with live DeltappGpp Salmonella efficiently protected mice from challenge with wild-type Salmonella at a dose 10(6)-fold above the LD50 30 days after immunization. Various assays revealed that immunization of mice with the DeltappGpp strain elicited both systemic and mucosal antibody responses, in addition to cell-mediated immunity.
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Affiliation(s)
- Hee Sam Na
- Genome Research Center for Enteropathogenic Bacteria and Research Institute of Vibrio Infection, South Korea
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Uzzau S, Marogna G, Leori GS, Curtiss R, Schianchi G, Stocker BAD, Rubino S. Virulence attenuation and live vaccine potential of aroA, crp cdt cya, and plasmid-cured mutants of Salmonella enterica serovar Abortusovis in mice and sheep. Infect Immun 2005; 73:4302-8. [PMID: 15972523 PMCID: PMC1168578 DOI: 10.1128/iai.73.7.4302-4308.2005] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Three live vaccine candidates of Salmonella enterica subspecies I serotype Abortusovis (aroA, cya crp cdt, and plasmid-cured strains) have been developed, and their efficacies in inducing humoral antibodies and protecting against abortion after challenge with wild-type strain SS44 were evaluated in sheep. Following estrus synchronization, animals were immunized 3 weeks after fertilization and boosted once 3 weeks later. Following challenge with wild-type SS44, pregnancy failure of vaccinated ewes was reduced compared to that of nonimmunized controls. Attenuation of each vaccine was also assessed in challenge experiments with nonimmunized pregnant ewes and in BALB/c mice. All three vaccine candidates appear to be safe for use in sheep and provide a model for the development of live vaccine candidates against naturally occurring ovine salmonellosis.
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Affiliation(s)
- Sergio Uzzau
- Dipartimento di Scienze Biomediche, Center for Biotechnology Development and Biodiversity Research, Università di Sassari, Italy
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Antigen Delivery Systems II: Development of Live Recombinant Attenuated Bacterial Antigen and DNA Vaccine Delivery Vector Vaccines. Mucosal Immunol 2005. [DOI: 10.1016/b978-012491543-5/50060-7] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
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