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Mansour MN, Yaghi J, El Khoury A, Felten A, Mistou MY, Atoui A, Radomski N. Prediction of Salmonella serovars isolated from clinical and food matrices in Lebanon and genomic-based investigation focusing on Enteritidis serovar. Int J Food Microbiol 2020; 333:108831. [PMID: 32854018 DOI: 10.1016/j.ijfoodmicro.2020.108831] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2020] [Revised: 08/09/2020] [Accepted: 08/10/2020] [Indexed: 12/17/2022]
Abstract
Salmonella enterica subsp. enterica serovars are considered major causes of food poisoning and we performed this study because Salmonella is a burden in Lebanon. The present study investigated the ability of genomic information to predict serovar using a collection of Salmonella isolates from infected humans (n = 24) and contaminated food (n = 63) in Lebanon. Further, the phylogenomic relationships of the serovar the predominated in Lebanon (i.e., S. Enteritidis; n = 25) were investigated in comparison with isolates from other countries (n = 130) based on coregenome single nucleotide polymorphisms (SNPs). Genetic elements, specifically Salmonella pathogenicity islands (SPIs), plasmid replicons, and antibiotic-resistance genes were screened in S. Enteritidis genomes (n = 155). Our results revealed that the Salmonella serovars identification by seroagglutination from the samples isolated in Lebanon (n = 87) was highly correlated with the genomic-based prediction of serovars (80.4-85.0% with SeqSero1 and 93.1-94.2% with SeqSero2). The Salmonella serovars isolated from human and food samples in Lebanon were mainly Enteritidis (28.7%) and Infantis (26%). To a rare extent, other serovars included Amager, Anatum, Bredeney, Chincol, Heidelberg, Hofit, Kentucky, Montevideo, Muenster, Newport, Schwarzengrund, Senftenberg and Typhimurium. In comparison with other countries, S. Enteritidis samples isolated in Lebanon (56 ± 27 intra-group pairwise SNP differences) presented a strong phylogenomic relativeness at the coregenome level with samples, as for example with samples isolated from Syria (65 ± 31 inter-group pairwise SNP differences). Most of the studied S. Enteritidis genomes encoded 10 SPIs involved in survival in immune cells (i.e. SPIs 1, 2, 3, 4, 5, 12, 13, 14, 16 and 17). The plasmid replicons IncFIB (S)_1 and IncFII (S)_1 encoding elements involved in virulence were identified in the majority of the S. Enteritidis genomes (94% and 96%, respectively), the majority exhibiting aminoglycosides (gene aac(6')-Iaa_1). The IncI_1_Alpha replicon responsible for ampicillin-resistance was only detected in 2 of 25 S. Enteritidis Lebanese strains. Genomic-based risk assessment of Salmonella serovars in Lebanon showed that food imported from Syria might be an origin of the S. Enteritidis human cases in Lebanon. The detection of several SPIs involved in the survival, plasmid replicons involved in virulence, and aminoglycoside-resistance genes, emphasizes that S. Enteritidis is of paramount importance for public health in Lebanon and other countries.
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Affiliation(s)
- Marie Noel Mansour
- Centre d'Analyses et de Recherche (CAR), Unité de Recherche « Technologies et Valorisation Agro-alimentaire » (UR-TVA), Faculty of Sciences, Saint-Joseph University of Beirut, Campus of Sciences and Technologies, Mar Roukos, Lebanon.
| | - Joseph Yaghi
- Centre d'Analyses et de Recherche (CAR), Unité de Recherche « Technologies et Valorisation Agro-alimentaire » (UR-TVA), Faculty of Sciences, Saint-Joseph University of Beirut, Campus of Sciences and Technologies, Mar Roukos, Lebanon.
| | - André El Khoury
- Centre d'Analyses et de Recherche (CAR), Unité de Recherche « Technologies et Valorisation Agro-alimentaire » (UR-TVA), Faculty of Sciences, Saint-Joseph University of Beirut, Campus of Sciences and Technologies, Mar Roukos, Lebanon.
| | - Arnaud Felten
- Paris-Est University, French Agency for Food, Environmental and Occupational Health and Safety (Anses), Laboratory for Food Safety (LSAL), Maisons-Alfort, France.
| | - Michel-Yves Mistou
- Applied Mathematics and Computer Science, From Genomes to the Environment (MaIAGE), National Institute for Agricultural, Food and Environmental Research (INRAE), Université Paris-Saclay, Jouy-en-Josas, France.
| | - Ali Atoui
- Laboratory of Microbiology, Department of Life and Earth Sciences, Faculty of Sciences I, Lebanese University, Hadat Campus, Beirut, Lebanon.
| | - Nicolas Radomski
- Paris-Est University, French Agency for Food, Environmental and Occupational Health and Safety (Anses), Laboratory for Food Safety (LSAL), Maisons-Alfort, France.
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Carneiro DG, Almeida FA, Aguilar AP, Vieira NM, Pinto UM, Mendes TAO, Vanetti MCD. Salmonella enterica Optimizes Metabolism After Addition of Acyl-Homoserine Lactone Under Anaerobic Conditions. Front Microbiol 2020; 11:1459. [PMID: 32849316 PMCID: PMC7401450 DOI: 10.3389/fmicb.2020.01459] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2019] [Accepted: 06/04/2020] [Indexed: 01/01/2023] Open
Abstract
Acyl-homoserine lactones (AHLs) are quorum sensing (QS) signaling molecules that mediate cell-to-cell communication in Gram-negative bacteria. Salmonella does not produce AHL, however, it can recognize AHLs produced by other species through SdiA protein modulating important cellular functions. In this work, the influence of the N-dodecanoyl-DL-homoserine lactone (C12-HSL) on glucose consumption, metabolic profile, and gene expression of Salmonella throughout the cultivation time in Tryptic Soy Broth (TSB) under anaerobic conditions was evaluated. Analysis of the supernatant culture in high-performance liquid chromatography (HPLC) revealed lower glucose uptake after 4 and 6 h of the addition of C12-HSL. Gas chromatography-mass spectrometry (GC-MS) based analysis of the intracellular metabolites revealed C12-HSL perturbation in the abundance levels of metabolites related to the metabolic pathways of glycerolipids, purines, amino acids, and aminoacyl-tRNA biosynthesis. The real-time quantitative PCR (RT-qPCR) indicated that Salmonella increase expression of genes associated with nucleoside degradation and quantification of metabolites supported the induction of pentose phosphate pathway to ensure growth under lower glucose consumption. The obtained data suggest an important role of C12-HSL in the optimization of metabolism at a situation of high population densities.
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Affiliation(s)
- Deisy G Carneiro
- Department of Microbiology, Universidade Federal de Viçosa, Viçosa, Brazil
| | - Felipe A Almeida
- Department of Nutrition, Universidade Federal de Juiz de Fora, Governador Valadares, Brazil
| | - Ananda P Aguilar
- Department of Biochemistry and Molecular Biology, Universidade Federal de Viçosa, Viçosa, Brazil
| | - Nívea M Vieira
- Department of Microbiology, Universidade Federal de Viçosa, Viçosa, Brazil
| | - Uelinton M Pinto
- Department of Food and Experimental Nutrition, Food Research Center, Universidade de São Paulo, São Paulo, Brazil
| | - Tiago A O Mendes
- Department of Biochemistry and Molecular Biology, Universidade Federal de Viçosa, Viçosa, Brazil
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Canaviri Paz P, Janny RJ, Håkansson Å. Safeguarding of quinoa beverage production by fermentation with Lactobacillus plantarum DSM 9843. Int J Food Microbiol 2020; 324:108630. [DOI: 10.1016/j.ijfoodmicro.2020.108630] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2020] [Revised: 03/25/2020] [Accepted: 04/11/2020] [Indexed: 12/24/2022]
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54
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Evolutionary causes and consequences of bacterial antibiotic persistence. Nat Rev Microbiol 2020; 18:479-490. [PMID: 32461608 DOI: 10.1038/s41579-020-0378-z] [Citation(s) in RCA: 114] [Impact Index Per Article: 22.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/17/2020] [Indexed: 12/12/2022]
Abstract
Antibiotic treatment failure is of growing concern. Genetically encoded resistance is key in driving this process. However, there is increasing evidence that bacterial antibiotic persistence, a non-genetically encoded and reversible loss of antibiotic susceptibility, contributes to treatment failure and emergence of resistant strains as well. In this Review, we discuss the evolutionary forces that may drive the selection for antibiotic persistence. We review how some aspects of antibiotic persistence have been directly selected for whereas others result from indirect selection in disparate ecological contexts. We then discuss the consequences of antibiotic persistence on pathogen evolution. Persisters can facilitate the evolution of antibiotic resistance and virulence. Finally, we propose practical means to prevent persister formation and how this may help to slow down the evolution of virulence and resistance in pathogens.
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Sofy AR, Abd El Haliem NF, Refaey EE, Hmed AA. Polyvalent Phage CoNShP-3 as a Natural Antimicrobial Agent Showing Lytic and Antibiofilm Activities against Antibiotic-Resistant Coagulase-Negative Staphylococci Strains. Foods 2020; 9:E673. [PMID: 32456227 PMCID: PMC7278617 DOI: 10.3390/foods9050673] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2020] [Revised: 05/18/2020] [Accepted: 05/19/2020] [Indexed: 12/15/2022] Open
Abstract
Synthetic antimicrobials have a negative impact on food quality and consumer health, which is why natural antimicrobials are urgently needed. Coagulase-negative staphylococci (CoNS) has gained considerable importance for food poisoning and infection in humans and animals, particularly in biofilms. As a result, this study was conducted to control the CoNS isolated from food samples in Egypt. CoNS isolates were selected on the basis of their antibiotic susceptibility profiles and their biofilm-associated behavior. In this context, a total of 29 different bacteriophages were isolated and, in particular, lytic phages (6 isolates) were selected. The host range and physiological parameters of the lytic phages have been studied. Electron microscopy images showed that lytic phages were members of the families Myoviridae (CoNShP-1, CoNShP-3, and CoNSeP-2 isolates) and Siphoviridae (CoNShP-2, CoNSsP-1, and CoNSeP-1 isolates). CoNShP-1, CoNShP-2, and CoNShP-3 were found to be virulent to Staphylococcus haemolyticus, CoNSsP-1 to Staphylococcus saprophyticus and CoNSeP-1 and CoNSeP-2 to Staphylococcus epidermidis. Interestingly, the CoNShP-exhibited a typical polyvalent behavior, where not only lysis CoNS, but also other genera include Staphylococcus aureus, methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant Staphylococcus aureus (VRSA), Bacillus cereus and Bacillus subtilis. In addition, CoNShP-3 phage showed high stability at different temperatures and pH levels. Indeed, CoNShP-3 phage showed an antibiofilm effect against Staphylococcus epidermidis CFS79 and Staphylococcus haemolyticus CFS43, respectively, while Staphylococcus saprophyticus CFS28 biofilm was completely removed. Finally, CoNShP-3 phage demonstrated a high preservative efficacy over short and long periods of storage against inoculated CoNS in chicken breast sections. In conclusion, this study highlights the control of CoNS pathogens using a polyvalent lytic phage as a natural antibacterial and antibiofilm agent from a food safety perspective.
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Affiliation(s)
- Ahmed R. Sofy
- Botany and Microbiology Department, Faculty of Science, Al-Azhar University, Nasr City, 11884 Cairo, Egypt;
| | - Naglaa F. Abd El Haliem
- Microbiology and Immunology Department, Faculty of Medicine (Girls), Al-Azhar University, Nasr City, 11884 Cairo, Egypt;
| | - Ehab E. Refaey
- Botany and Microbiology Department, Faculty of Science, Al-Azhar University, Nasr City, 11884 Cairo, Egypt;
| | - Ahmed A. Hmed
- Botany and Microbiology Department, Faculty of Science, Al-Azhar University, Nasr City, 11884 Cairo, Egypt;
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Lerminiaux NA, MacKenzie KD, Cameron ADS. Salmonella Pathogenicity Island 1 (SPI-1): The Evolution and Stabilization of a Core Genomic Type Three Secretion System. Microorganisms 2020; 8:microorganisms8040576. [PMID: 32316180 PMCID: PMC7232297 DOI: 10.3390/microorganisms8040576] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2020] [Revised: 04/10/2020] [Accepted: 04/10/2020] [Indexed: 11/16/2022] Open
Abstract
Salmonella Pathogenicity Island 1 (SPI-1) encodes a type three secretion system (T3SS), effector proteins, and associated transcription factors that together enable invasion of epithelial cells in animal intestines. The horizontal acquisition of SPI-1 by the common ancestor of all Salmonella is considered a prime example of how gene islands potentiate the emergence of new pathogens with expanded niche ranges. However, the evolutionary history of SPI-1 has attracted little attention. Here, we apply phylogenetic comparisons across the family Enterobacteriaceae to examine the history of SPI-1, improving the resolution of its boundaries and unique architecture by identifying its composite gene modules. SPI-1 is located between the core genes fhlA and mutS, a hotspot for the gain and loss of horizontally acquired genes. Despite the plasticity of this locus, SPI-1 demonstrates stable residency of many tens of millions of years in a host genome, unlike short-lived homologous T3SS and effector islands including Escherichia ETT2, Yersinia YSA, Pantoea PSI-2, Sodalis SSR2, and Chromobacterium CPI-1. SPI-1 employs a unique series of regulatory switches, starting with the dedicated transcription factors HilC and HilD, and flowing through the central SPI-1 regulator HilA. HilA is shared with other T3SS, but HilC and HilD may have their evolutionary origins in Salmonella. The hilA, hilC, and hilD gene promoters are the most AT-rich DNA in SPI-1, placing them under tight control by the transcriptional repressor H-NS. In all Salmonella lineages, these three promoters resist amelioration towards the genomic average, ensuring strong repression by H-NS. Hence, early development of a robust and well-integrated regulatory network may explain the evolutionary stability of SPI-1 compared to T3SS gene islands in other species.
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Affiliation(s)
- Nicole A. Lerminiaux
- Department of Biology, Faculty of Science, University of Regina, Regina, SK S4S 0A2, Canada; (N.A.L.); (K.D.M.)
- Institute for Microbial Systems and Society, Faculty of Science, University of Regina, Regina, SK S4S 0A2, Canada
| | - Keith D. MacKenzie
- Department of Biology, Faculty of Science, University of Regina, Regina, SK S4S 0A2, Canada; (N.A.L.); (K.D.M.)
- Institute for Microbial Systems and Society, Faculty of Science, University of Regina, Regina, SK S4S 0A2, Canada
| | - Andrew D. S. Cameron
- Department of Biology, Faculty of Science, University of Regina, Regina, SK S4S 0A2, Canada; (N.A.L.); (K.D.M.)
- Institute for Microbial Systems and Society, Faculty of Science, University of Regina, Regina, SK S4S 0A2, Canada
- Correspondence:
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Nagy T, Szmolka A, Wilk T, Kiss J, Szabó M, Pászti J, Nagy B, Olasz F. Comparative Genome Analysis of Hungarian and Global Strains of Salmonella Infantis. Front Microbiol 2020; 11:539. [PMID: 32318036 PMCID: PMC7147451 DOI: 10.3389/fmicb.2020.00539] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2019] [Accepted: 03/12/2020] [Indexed: 12/11/2022] Open
Abstract
INTRODUCTION The emergence and spread of new strains of zoonotic bacteria, such as multidrug resistant (MDR) Salmonella Infantis, represent a growing health risk for humans in and outside Europe due to foodborne infections of poultry meat origin. OBJECTIVES In order to understand genome relations of S. Infantis strains from Hungary and from different geographic regions, we performed a comprehensive genome analysis of nine Hungarian and 67 globally selected strains of S. Infantis and 26 Salmonella strains representing 13 non-Infantis serovars. RESULTS Analyses of whole-, and accessory genomes, showed that almost all S. Infantis strains were separated from the non-Infantis serovars. S. Infantis strains from Hungary formed subclusters based on their time of isolation. In whole genome sequence analysis, the Swiss strains of S. Infantis were closely related to each other and clustered together with subclusters of strains from Hungary, Japan, Italy, United States, and Israel. The accessory genome analysis revealed that the Swiss strains were distinct from most of the strains investigated, including the Hungarian ones. Analysis of the cloud genes offered the most detailed insight into the genetic distance and relationship of S. Infantis strains confirming that the Swiss and Hungarian strains belonged to different lineages. As expected, core genome analysis provided the least discriminatory power for analysis of S. Infantis. Genomic sequences of nine strains from Brazil, Israel, Mexico, Nigeria, and Senegal (deposited as S. Infantis) proved to be outliers from the S. Infantis clade. They were predicted to be Salmonella Rissen, Salmonella Ouakarm, Salmonella Kentucky, Salmonella Thompson, and Salmonella enterica subsp. diarizonae. CONCLUSION Accessory genome of S. Infantis showed the highest diversity suggesting a faster evolution than that of the whole genomes contributing to the emergence of multiple genetic variants of S. Infantis worldwide. Accordingly, in spite of the comprehensive analysis of several genomic characteristics, no epidemiologic links between these S. Infantis strains from different countries could be established. It is also concluded that several strains originally designated as S. Infantis need in databanks reclassification.
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Affiliation(s)
- Tibor Nagy
- National Agricultural Research and Innovation Centre, Agricultural Biotechnology Institute, Gödöllő, Hungary
| | - Ama Szmolka
- Centre for Agricultural Research, Institute for Veterinary Medical Research, Budapest, Hungary
| | - Tímea Wilk
- National Agricultural Research and Innovation Centre, Agricultural Biotechnology Institute, Gödöllő, Hungary
| | - János Kiss
- National Agricultural Research and Innovation Centre, Agricultural Biotechnology Institute, Gödöllő, Hungary
| | - Mónika Szabó
- National Agricultural Research and Innovation Centre, Agricultural Biotechnology Institute, Gödöllő, Hungary
| | - Judit Pászti
- National Center for Epidemiology, Budapest, Hungary
| | - Béla Nagy
- Centre for Agricultural Research, Institute for Veterinary Medical Research, Budapest, Hungary
| | - Ferenc Olasz
- National Agricultural Research and Innovation Centre, Agricultural Biotechnology Institute, Gödöllő, Hungary
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Type III Secretion Effectors with Arginine N-Glycosyltransferase Activity. Microorganisms 2020; 8:microorganisms8030357. [PMID: 32131463 PMCID: PMC7142665 DOI: 10.3390/microorganisms8030357] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2020] [Revised: 02/27/2020] [Accepted: 02/29/2020] [Indexed: 01/31/2023] Open
Abstract
Type III secretion systems are used by many Gram-negative bacterial pathogens to inject proteins, known as effectors, into the cytosol of host cells. These virulence factors interfere with a diverse array of host signal transduction pathways and cellular processes. Many effectors have catalytic activities to promote post-translational modifications of host proteins. This review focuses on a family of effectors with glycosyltransferase activity that catalyze addition of N-acetyl-d-glucosamine to specific arginine residues in target proteins, leading to reduced NF-κB pathway activation and impaired host cell death. This family includes NleB from Citrobacter rodentium, NleB1 and NleB2 from enteropathogenic and enterohemorrhagic Escherichia coli, and SseK1, SseK2, and SseK3 from Salmonella enterica. First, we place these effectors in the general framework of the glycosyltransferase superfamily and in the particular context of the role of glycosylation in bacterial pathogenesis. Then, we provide detailed information about currently known members of this family, their role in virulence, and their targets.
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Rihtar E, Žgur Bertok D, Podlesek Z. The Uropathogenic Specific Protein Gene usp from Escherichia coli and Salmonella bongori is a Novel Member of the TyrR and H-NS Regulons. Microorganisms 2020; 8:E330. [PMID: 32111072 PMCID: PMC7142922 DOI: 10.3390/microorganisms8030330] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2020] [Accepted: 02/25/2020] [Indexed: 12/16/2022] Open
Abstract
The Escherichia coli PAIusp is a small pathogenicity island encoding usp, for the uropathogenic specific protein (Usp), a genotoxin and three associated downstream imu1-3 genes that protect the producer against its own toxin. Bioinformatic analysis revealed the presence of the PAIusp also in publically available Salmonella bongori and Salmonella enterica subps. salamae genome sequences. PAIusp is in all examined sequences integrated within the aroP-pdhR chromosomal intergenic region. The focus of this work was identification of the usp promoter and regulatory elements controlling its activity. We show that, in both E. coli and S. bongori, the divergent TyrR regulated P3 promoter of the aroP gene, encoding an aromatic amino acid membrane transporter, drives usp transcription while H-NS acts antagonistically repressing expression. Our results show that the horizontally acquired PAIusp has integrated into the TyrR regulatory network and that environmental factors such as aromatic amino acids, temperature and urea induce usp expression.
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Affiliation(s)
- Erik Rihtar
- Biotechnical Faculty, University of Ljubljana, 1000 Ljubljana, Slovenia; (E.R.); (Z.P.)
- National Institute of Chemistry, 1000 Ljubljana, Slovenia
| | - Darja Žgur Bertok
- Biotechnical Faculty, University of Ljubljana, 1000 Ljubljana, Slovenia; (E.R.); (Z.P.)
| | - Zdravko Podlesek
- Biotechnical Faculty, University of Ljubljana, 1000 Ljubljana, Slovenia; (E.R.); (Z.P.)
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60
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Wang X, Zhu S, Zhao JH, Bao HX, Liu H, Ding TM, Liu GR, Li YG, Johnston RN, Cao FL, Tang L, Liu SL. Genetic boundaries delineate the potential human pathogen Salmonella bongori into discrete lineages: divergence and speciation. BMC Genomics 2019; 20:930. [PMID: 31801462 PMCID: PMC6894293 DOI: 10.1186/s12864-019-6259-z] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2019] [Accepted: 11/05/2019] [Indexed: 12/13/2022] Open
Abstract
BACKGROUND Salmonella bongori infect mainly cold-blooded hosts, but infections by S. bongori in warm-blooded hosts have been reported. We hypothesized that S. bongori might have diverged into distinct phylogenetic lineages, with some being able to infect warm-blooded hosts. RESULTS To inspect the divergence status of S. bongori, we first completely sequenced the parakeet isolate RKS3044 and compared it with other sequenced S. bongori strains. We found that RKS3044 contained a novel T6SS encoded in a pathogenicity island-like structure, in addition to a T6SS encoded in SPI-22, which is common to all S. bongori strains so far reported. This novel T6SS resembled the SPI-19 T6SS of the warm-blooded host infecting Salmonella Subgroup I lineages. Genomic sequence comparisons revealed different genomic sequence amelioration events among the S. bongori strains, including a unique CTAG tetranucleotide degeneration pattern in RKS3044, suggesting non-overlapping gene pools between RKS3044 and other S. bongori lineages/strains leading to their independent accumulation of genomic variations. We further proved the existence of a clear-cut genetic boundary between RKS3044 and the other S. bongori lineages/strains analyzed in this study. CONCLUSIONS The warm-blooded host-infecting S. bongori strain RKS3044 has diverged with distinct genomic features from other S. bongori strains, including a novel T6SS encoded in a previously not reported pathogenicity island-like structure and a unique genomic sequence degeneration pattern. These findings alert cautions about the emergence of new pathogens originating from non-pathogenic ancestors by acquiring specific pathogenic traits.
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Affiliation(s)
- Xiaoyu Wang
- Systemomics Center, College of Pharmacy, and Genomics Research Center (State-Province Key Laboratories of Biomedicine-Pharmaceutics of China), Harbin Medical University, 157 Baojian Road, Harbin, 150081 China
- HMU-UCCSM Centre for Infection and Genomics, Harbin Medical University, Harbin, China
- Translational Medicine Research and Cooperation Center of Northern China, Heilongjiang Academy of Medical Sciences, Harbin, China
| | - Songling Zhu
- Systemomics Center, College of Pharmacy, and Genomics Research Center (State-Province Key Laboratories of Biomedicine-Pharmaceutics of China), Harbin Medical University, 157 Baojian Road, Harbin, 150081 China
- HMU-UCCSM Centre for Infection and Genomics, Harbin Medical University, Harbin, China
- Translational Medicine Research and Cooperation Center of Northern China, Heilongjiang Academy of Medical Sciences, Harbin, China
| | - Jian-Hua Zhao
- Systemomics Center, College of Pharmacy, and Genomics Research Center (State-Province Key Laboratories of Biomedicine-Pharmaceutics of China), Harbin Medical University, 157 Baojian Road, Harbin, 150081 China
- HMU-UCCSM Centre for Infection and Genomics, Harbin Medical University, Harbin, China
- Translational Medicine Research and Cooperation Center of Northern China, Heilongjiang Academy of Medical Sciences, Harbin, China
| | - Hong-Xia Bao
- Systemomics Center, College of Pharmacy, and Genomics Research Center (State-Province Key Laboratories of Biomedicine-Pharmaceutics of China), Harbin Medical University, 157 Baojian Road, Harbin, 150081 China
- HMU-UCCSM Centre for Infection and Genomics, Harbin Medical University, Harbin, China
- Translational Medicine Research and Cooperation Center of Northern China, Heilongjiang Academy of Medical Sciences, Harbin, China
| | - Huidi Liu
- Systemomics Center, College of Pharmacy, and Genomics Research Center (State-Province Key Laboratories of Biomedicine-Pharmaceutics of China), Harbin Medical University, 157 Baojian Road, Harbin, 150081 China
- HMU-UCCSM Centre for Infection and Genomics, Harbin Medical University, Harbin, China
- Translational Medicine Research and Cooperation Center of Northern China, Heilongjiang Academy of Medical Sciences, Harbin, China
| | - Tie-Min Ding
- Department of Medicine and Food Engineering, Harbin Labor Technician College, Harbin, China
| | - Gui-Rong Liu
- Systemomics Center, College of Pharmacy, and Genomics Research Center (State-Province Key Laboratories of Biomedicine-Pharmaceutics of China), Harbin Medical University, 157 Baojian Road, Harbin, 150081 China
- HMU-UCCSM Centre for Infection and Genomics, Harbin Medical University, Harbin, China
- Translational Medicine Research and Cooperation Center of Northern China, Heilongjiang Academy of Medical Sciences, Harbin, China
| | - Yong-Guo Li
- Department of Infectious Diseases, The First Affiliated Hospital, Harbin Medical University, Harbin, China
| | - Randal N. Johnston
- Department of Biochemistry and Molecular Biology, University of Calgary, Calgary, Canada
| | - Feng-Lin Cao
- Systemomics Center, College of Pharmacy, and Genomics Research Center (State-Province Key Laboratories of Biomedicine-Pharmaceutics of China), Harbin Medical University, 157 Baojian Road, Harbin, 150081 China
- Department of Hematology, The First Affiliated Hospital, Harbin Medical University, Harbin, China
| | - Le Tang
- Systemomics Center, College of Pharmacy, and Genomics Research Center (State-Province Key Laboratories of Biomedicine-Pharmaceutics of China), Harbin Medical University, 157 Baojian Road, Harbin, 150081 China
- HMU-UCCSM Centre for Infection and Genomics, Harbin Medical University, Harbin, China
- Translational Medicine Research and Cooperation Center of Northern China, Heilongjiang Academy of Medical Sciences, Harbin, China
- Department of Ecosystems and Public Health, University of Calgary, Calgary, Canada
| | - Shu-Lin Liu
- Systemomics Center, College of Pharmacy, and Genomics Research Center (State-Province Key Laboratories of Biomedicine-Pharmaceutics of China), Harbin Medical University, 157 Baojian Road, Harbin, 150081 China
- HMU-UCCSM Centre for Infection and Genomics, Harbin Medical University, Harbin, China
- Translational Medicine Research and Cooperation Center of Northern China, Heilongjiang Academy of Medical Sciences, Harbin, China
- Department of Infectious Diseases, The First Affiliated Hospital, Harbin Medical University, Harbin, China
- Department of Microbiology, Immunology and Infectious Diseases, University of Calgary, Calgary, Canada
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Pokharel P, Habouria H, Bessaiah H, Dozois CM. Serine Protease Autotransporters of the Enterobacteriaceae (SPATEs): Out and About and Chopping It Up. Microorganisms 2019; 7:E594. [PMID: 31766493 PMCID: PMC6956023 DOI: 10.3390/microorganisms7120594] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2019] [Accepted: 11/13/2019] [Indexed: 02/06/2023] Open
Abstract
Autotransporters are secreted proteins with multiple functions produced by a variety of Gram-negative bacteria. In Enterobacteriaceae, a subgroup of these autotransporters are the SPATEs (serine protease autotransporters of Enterobacteriaceae). SPATEs play a crucial role in survival and virulence of pathogens such as Escherichia coli and Shigella spp. and contribute to intestinal and extra-intestinal infections. These high molecular weight proteases are transported to the external milieu by the type Va secretion system and function as proteases with diverse substrate specificities and biological functions including adherence and cytotoxicity. Herein, we provide an overview of SPATEs and discuss recent findings on the biological roles of these secreted proteins, including proteolysis of substrates, adherence to cells, modulation of the immune response, and virulence in host models. In closing, we highlight recent insights into the regulation of expression of SPATEs that could be exploited to understand fundamental SPATE biology.
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Affiliation(s)
- Pravil Pokharel
- Institut National de Recherche Scientifique (INRS)-Centre Armand-Frappier Santé Biotechnologie, Laval, QC H7V 1B7, Canada; (P.P.); (H.H.); (H.B.)
- Centre de Recherche en Infectiologie Porcine et Avicole (CRIPA), Saint-Hyacinthe, QC J2S 2M2, Canada
| | - Hajer Habouria
- Institut National de Recherche Scientifique (INRS)-Centre Armand-Frappier Santé Biotechnologie, Laval, QC H7V 1B7, Canada; (P.P.); (H.H.); (H.B.)
- Centre de Recherche en Infectiologie Porcine et Avicole (CRIPA), Saint-Hyacinthe, QC J2S 2M2, Canada
| | - Hicham Bessaiah
- Institut National de Recherche Scientifique (INRS)-Centre Armand-Frappier Santé Biotechnologie, Laval, QC H7V 1B7, Canada; (P.P.); (H.H.); (H.B.)
- Centre de Recherche en Infectiologie Porcine et Avicole (CRIPA), Saint-Hyacinthe, QC J2S 2M2, Canada
| | - Charles M. Dozois
- Institut National de Recherche Scientifique (INRS)-Centre Armand-Frappier Santé Biotechnologie, Laval, QC H7V 1B7, Canada; (P.P.); (H.H.); (H.B.)
- Centre de Recherche en Infectiologie Porcine et Avicole (CRIPA), Saint-Hyacinthe, QC J2S 2M2, Canada
- Institut Pasteur International Network, Laval, QC H7V 1B7, Canada
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Vila Nova M, Durimel K, La K, Felten A, Bessières P, Mistou MY, Mariadassou M, Radomski N. Genetic and metabolic signatures of Salmonella enterica subsp. enterica associated with animal sources at the pangenomic scale. BMC Genomics 2019; 20:814. [PMID: 31694533 PMCID: PMC6836353 DOI: 10.1186/s12864-019-6188-x] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2019] [Accepted: 10/15/2019] [Indexed: 12/14/2022] Open
Abstract
BACKGROUND Salmonella enterica subsp. enterica is a public health issue related to food safety, and its adaptation to animal sources remains poorly described at the pangenome scale. Firstly, serovars presenting potential mono- and multi-animal sources were selected from a curated and synthetized subset of Enterobase. The corresponding sequencing reads were downloaded from the European Nucleotide Archive (ENA) providing a balanced dataset of 440 Salmonella genomes in terms of serovars and sources (i). Secondly, the coregenome variants and accessory genes were detected (ii). Thirdly, single nucleotide polymorphisms and small insertions/deletions from the coregenome, as well as the accessory genes were associated to animal sources based on a microbial Genome Wide Association Study (GWAS) integrating an advanced correction of the population structure (iii). Lastly, a Gene Ontology Enrichment Analysis (GOEA) was applied to emphasize metabolic pathways mainly impacted by the pangenomic mutations associated to animal sources (iv). RESULTS Based on a genome dataset including Salmonella serovars from mono- and multi-animal sources (i), 19,130 accessory genes and 178,351 coregenome variants were identified (ii). Among these pangenomic mutations, 52 genomic signatures (iii) and 9 over-enriched metabolic signatures (iv) were associated to avian, bovine, swine and fish sources by GWAS and GOEA, respectively. CONCLUSIONS Our results suggest that the genetic and metabolic determinants of Salmonella adaptation to animal sources may have been driven by the natural feeding environment of the animal, distinct livestock diets modified by human, environmental stimuli, physiological properties of the animal itself, and work habits for health protection of livestock.
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Affiliation(s)
- Meryl Vila Nova
- French Agency for Food, Environmental and Occupational Health and Safety (Anses), Laboratory for Food Safety (LSAL), Paris-Est University, Maisons-Alfort, France
- Applied Mathematics and Computer Science, from Genomes to the Environment (MaIAGE), French National Institute for Agricultural Research (INRA), Université Paris-Saclay, 78350, Jouy-en-Josas, France
| | - Kévin Durimel
- French Agency for Food, Environmental and Occupational Health and Safety (Anses), Laboratory for Food Safety (LSAL), Paris-Est University, Maisons-Alfort, France
| | - Kévin La
- French Agency for Food, Environmental and Occupational Health and Safety (Anses), Laboratory for Food Safety (LSAL), Paris-Est University, Maisons-Alfort, France
| | - Arnaud Felten
- French Agency for Food, Environmental and Occupational Health and Safety (Anses), Laboratory for Food Safety (LSAL), Paris-Est University, Maisons-Alfort, France
| | - Philippe Bessières
- Applied Mathematics and Computer Science, from Genomes to the Environment (MaIAGE), French National Institute for Agricultural Research (INRA), Université Paris-Saclay, 78350, Jouy-en-Josas, France
| | - Michel-Yves Mistou
- French Agency for Food, Environmental and Occupational Health and Safety (Anses), Laboratory for Food Safety (LSAL), Paris-Est University, Maisons-Alfort, France
| | - Mahendra Mariadassou
- Applied Mathematics and Computer Science, from Genomes to the Environment (MaIAGE), French National Institute for Agricultural Research (INRA), Université Paris-Saclay, 78350, Jouy-en-Josas, France
| | - Nicolas Radomski
- French Agency for Food, Environmental and Occupational Health and Safety (Anses), Laboratory for Food Safety (LSAL), Paris-Est University, Maisons-Alfort, France.
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The Ferric Uptake Regulator Represses Type VI Secretion System Function by Binding Directly to the clpV Promoter in Salmonella enterica Serovar Typhimurium. Infect Immun 2019; 87:IAI.00562-19. [PMID: 31383745 DOI: 10.1128/iai.00562-19] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2019] [Accepted: 07/25/2019] [Indexed: 12/16/2022] Open
Abstract
Type VI secretion systems (T6SSs) are highly conserved and complex protein secretion systems that deliver effector proteins into eukaryotic hosts or other bacteria. T6SSs are regulated precisely by a variety of regulatory systems, which enables bacteria to adapt to varied environments. A T6SS within Salmonella pathogenicity island 6 (SPI-6) is activated during infection, and it contributes to the pathogenesis, as well as interbacterial competition, of Salmonella enterica serovar Typhimurium (S. Typhimurium). However, the regulation of the SPI-6 T6SS in S. Typhimurium is not well understood. In this study, we found that the SPI-6 T6SS core gene clpV was significantly upregulated in response to the iron-depleted condition and during infection. The global ferric uptake regulator (Fur) was shown to repress the clpV expression in the iron-replete medium. Moreover, electrophoretic mobility shift and DNase I footprinting assays revealed that Fur binds directly to the clpV promoter region at multiple sites spanning the transcriptional start site. We also observed that the relieving of Fur-mediated repression on clpV contributed to the interbacterial competition activity and pathogenicity of S. Typhimurium. These findings provide insights into the direct regulation of Fur in the expression and functional activity of SPI-6 T6SS in S. Typhimurium and thus help to elucidate the mechanisms of bacterial adaptability and virulence.
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64
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Riquelme NA, Leon MF, Santander JA, Robeson JP. Productive infection and transduction by bacteriophage P1 in the species Salmonella bongori. ELECTRON J BIOTECHN 2019. [DOI: 10.1016/j.ejbt.2019.04.011] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
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65
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Mthembu TP, Zishiri OT, El Zowalaty ME. Detection and Molecular Identification of Salmonella Virulence Genes in Livestock Production Systems in South Africa. Pathogens 2019; 8:pathogens8030124. [PMID: 31405078 PMCID: PMC6789496 DOI: 10.3390/pathogens8030124] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2019] [Revised: 07/26/2019] [Accepted: 08/05/2019] [Indexed: 01/07/2023] Open
Abstract
Livestock are an important source of protein and food for humans, however opportunistic pathogens such as Salmonella spp. turn livestock into vehicles of foodborne diseases. This study investigated the prevalence of virulence genes in Salmonella spp. isolated from livestock production systems in two provinces of South Africa. During the period from May to August, 2018, a total of 361 faecal (189), oral (100), environmental (soil (36) and water (27)) and feed (9) samples were randomly collected from different animals (cattle, sheep, goats, pigs, ducks and chickens) that were housed in small-scale livestock production systems from Eastern Cape and KwaZulu-Natal Provinces in South Africa. Salmonella spp. were isolated and identified using microbiological and DNA molecular methods. Salmonella spp. were present in 29.0% of the samples of which 30.2% belonged to the Salmonella enterica species as confirmed by the positive amplification of the species specific iroB gene. Virulence genes that were screened from livestock-associated Salmonella were invA, iroB, spiC, pipD and int1. Statistically significant associations (p < 0.05) were established between the virulence genes, sampling location, animal host as well as the season when samples were collected. Furthermore, statistically significant (p < 0.05) positive correlations were observed between most of the virulence genes investigated. This is one of the recent studies to detect and investigate livestock-associated Salmonella spp. in South Africa. This study highlights the importance of continuous monitoring and surveillance for pathogenic salmonellae. It also demonstrated the detection and prevalence of virulent Salmonella spp. harbored by livestock in South Africa. This study demonstrated the potential risks of pathogenic Salmonella enterica to cause foodborne diseases and zoonotic infections from farm-to-fork continuum using the global one-health approach.
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Affiliation(s)
- Thobeka P Mthembu
- Discipline of Genetics, School of Life Sciences, University of KwaZulu-Natal, Private Bag X54001, Durban 4000, South Africa
| | - Oliver T Zishiri
- Discipline of Genetics, School of Life Sciences, University of KwaZulu-Natal, Private Bag X54001, Durban 4000, South Africa
| | - Mohamed E El Zowalaty
- Virology and Microbiology Research Group, College of Pharmacy City University College of Ajman, Al Tallah 2, Ajman, P.O. Box 18484, UAE.
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66
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Wang Y, Cai Y, Zhang J, Liu D, Gong X, Pan Z, Geng S, Jiao X. Controversy Surrounding the Function of SpiC Protein in Salmonella: An Overview. Front Microbiol 2019; 10:1784. [PMID: 31440219 PMCID: PMC6693482 DOI: 10.3389/fmicb.2019.01784] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2019] [Accepted: 07/18/2019] [Indexed: 01/19/2023] Open
Abstract
Salmonella is an important pathogenic microorganism that can infect humans and animals and has been studied globally as a model microorganism for its pathogenesis. The SpiC protein of T3SS2 is a significant factor that has been studied for almost 20 years, but to date, the function/effect of SpiC in the pathogenesis of Salmonella has not been completely understood. There is controversy over the functions of SpiC protein in the literature. Thus, an overview of the literature on SpiC protein is provided here which highlights expression features of SpiC protein and its various functions and effect.
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Affiliation(s)
- Yaonan Wang
- College of Bioscience and Biotechnology and College of Veterinary Medicine, Jiangsu Key Laboratory of Zoonosis, Jiangsu Co-Innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou University, Yangzhou, China
| | - Yuan Cai
- College of Bioscience and Biotechnology and College of Veterinary Medicine, Jiangsu Key Laboratory of Zoonosis, Jiangsu Co-Innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou University, Yangzhou, China
| | - Jian Zhang
- College of Bioscience and Biotechnology and College of Veterinary Medicine, Jiangsu Key Laboratory of Zoonosis, Jiangsu Co-Innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou University, Yangzhou, China
| | - Dong Liu
- Research and Development Center, State Key Laboratory of Genetically Engineered Veterinary Vaccines, Yebio Bioengineering Co., Ltd of Qingdao, Qingdao, China
| | - Xiao Gong
- Research and Development Center, State Key Laboratory of Genetically Engineered Veterinary Vaccines, Yebio Bioengineering Co., Ltd of Qingdao, Qingdao, China
| | - Zhiming Pan
- College of Bioscience and Biotechnology and College of Veterinary Medicine, Jiangsu Key Laboratory of Zoonosis, Jiangsu Co-Innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou University, Yangzhou, China
| | - Shizhong Geng
- College of Bioscience and Biotechnology and College of Veterinary Medicine, Jiangsu Key Laboratory of Zoonosis, Jiangsu Co-Innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou University, Yangzhou, China
| | - Xin'an Jiao
- College of Bioscience and Biotechnology and College of Veterinary Medicine, Jiangsu Key Laboratory of Zoonosis, Jiangsu Co-Innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou University, Yangzhou, China
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Criscuolo A, Issenhuth-Jeanjean S, Didelot X, Thorell K, Hale J, Parkhill J, Thomson NR, Weill FX, Falush D, Brisse S. The speciation and hybridization history of the genus Salmonella. Microb Genom 2019; 5. [PMID: 31347998 PMCID: PMC6755497 DOI: 10.1099/mgen.0.000284] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
Bacteria and archaea make up most of natural diversity, but the mechanisms that underlie the origin and maintenance of prokaryotic species are poorly understood. We investigated the speciation history of the genus Salmonella, an ecologically diverse bacterial lineage, within which S. enterica subsp. enterica is responsible for important human food-borne infections. We performed a survey of diversity across a large reference collection using multilocus sequence typing, followed by genome sequencing of distinct lineages. We identified 11 distinct phylogroups, 3 of which were previously undescribed. Strains assigned to S. enterica subsp. salamae are polyphyletic, with two distinct lineages that we designate Salamae A and B. Strains of the subspecies houtenae are subdivided into two groups, Houtenae A and B, and are both related to Selander’s group VII. A phylogroup we designate VIII was previously unknown. A simple binary fission model of speciation cannot explain observed patterns of sequence diversity. In the recent past, there have been large-scale hybridization events involving an unsampled ancestral lineage and three distantly related lineages of the genus that have given rise to Houtenae A, Houtenae B and VII. We found no evidence for ongoing hybridization in the other eight lineages, but detected subtler signals of ancient recombination events. We are unable to fully resolve the speciation history of the genus, which might have involved additional speciation-by-hybridization or multi-way speciation events. Our results imply that traditional models of speciation by binary fission and divergence are not sufficient to account for Salmonella evolution.
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Affiliation(s)
- Alexis Criscuolo
- Hub de Bioinformatique et Biostatistique - Département Biologie Computationnelle, Institut Pasteur, USR 3756 CNRS, Paris, France
| | - Sylvie Issenhuth-Jeanjean
- Institut Pasteur, Unité des Bactéries Pathogènes Entériques, World Health Organization Collaborating Centre for Reference and Research on Salmonella, Paris, France
| | - Xavier Didelot
- School of Life Sciences and Department of Statistics, University of Warwick, Coventry, UK
| | - Kaisa Thorell
- Department of Microbiology and Immunology, University of Gothenburg, Gothenburg, Sweden
| | - James Hale
- Environmental Research Institute, University College Cork, Cork, Ireland
| | | | | | - François-Xavier Weill
- Institut Pasteur, Unité des Bactéries Pathogènes Entériques, World Health Organization Collaborating Centre for Reference and Research on Salmonella, Paris, France
| | - Daniel Falush
- The Milner Centre for Evolution, University of Bath, Bath, UK
| | - Sylvain Brisse
- Institut Pasteur, Biodiversity and Epidemiology of Bacterial Pathogens, Paris, France
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68
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Hews CL, Pritchard EJ, Rowley G. The Salmonella Specific, σ E-Regulated, STM1250 and AgsA, Function With the sHsps IbpA and IbpB, to Counter Oxidative Stress and Survive Macrophage Killing. Front Cell Infect Microbiol 2019; 9:263. [PMID: 31396489 PMCID: PMC6663981 DOI: 10.3389/fcimb.2019.00263] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2019] [Accepted: 07/04/2019] [Indexed: 11/13/2022] Open
Abstract
The host presents an array of environments which induce bacterial stress including changes in pH, antimicrobial compounds and reactive oxygen species. The bacterial envelope sits at the interface between the intracellular and extracellular environment and its maintenance is essential for Salmonella cell viability under a range of conditions, including during infection. In this study, we aimed to understand the contribution of the σH- and σE-regulated small heat shock proteins IbpA, IbpB, and AgsA and the putative σE-regulated stress response protein STM1250 to the Salmonella envelope stress response. Due to shared sequence identity, regulatory overlap, and the specificity of STM1250 and AgsA to Salmonella sp., we hypothesized that functional overlap exists between these four stress response proteins, which might afford a selective advantage during Salmonella exposure to stress. We present here new roles for three small heat shock proteins and a putative stress response protein in Salmonella that are not limited to heat shock. We have shown that, compared to WT, a quadruple mutant is significantly more sensitive to hydrogen peroxide, has a lower minimum bactericidal concentration to the cationic antimicrobial peptide polymyxin B, and is attenuated in macrophages.
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Affiliation(s)
- Claire L Hews
- School of Biological Sciences, University of East Anglia, Norwich, United Kingdom
| | - Emily J Pritchard
- School of Biological Sciences, University of East Anglia, Norwich, United Kingdom
| | - Gary Rowley
- School of Biological Sciences, University of East Anglia, Norwich, United Kingdom
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69
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Cheng RA, Wiedmann M. The ADP-Ribosylating Toxins of Salmonella. Toxins (Basel) 2019; 11:E416. [PMID: 31315299 PMCID: PMC6669713 DOI: 10.3390/toxins11070416] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2019] [Revised: 07/10/2019] [Accepted: 07/10/2019] [Indexed: 12/22/2022] Open
Abstract
A number of pathogenic bacteria utilize toxins to mediate disease in a susceptible host. The foodborne pathogen Salmonella is one of the most important and well-studied bacterial pathogens. Recently, whole genome sequence characterizations revealed the presence of multiple novel ADP-ribosylating toxins encoded by a variety of Salmonella serovars. In this review, we discuss both the classical (SpvB) and novel (typhoid toxin, ArtAB, and SboC/SeoC) ADP-ribosylating toxins of Salmonella, including the structure and function of these toxins and our current understanding of their contributions to virulence.
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Affiliation(s)
- Rachel A Cheng
- Department of Food Science, Cornell University, Ithaca, NY 14853, USA.
| | - Martin Wiedmann
- Department of Food Science, Cornell University, Ithaca, NY 14853, USA
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70
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Cheng RA, Eade CR, Wiedmann M. Embracing Diversity: Differences in Virulence Mechanisms, Disease Severity, and Host Adaptations Contribute to the Success of Nontyphoidal Salmonella as a Foodborne Pathogen. Front Microbiol 2019; 10:1368. [PMID: 31316476 PMCID: PMC6611429 DOI: 10.3389/fmicb.2019.01368] [Citation(s) in RCA: 105] [Impact Index Per Article: 17.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2018] [Accepted: 05/31/2019] [Indexed: 12/19/2022] Open
Abstract
Not all Salmonella enterica serovars cause the same disease. S. enterica represents an incredibly diverse species comprising >2,600 unique serovars. While some S. enterica serovars are host-restricted, others infect a wide range of hosts. The diseases that nontyphoidal Salmonella (NTS) serovars cause vary considerably, with some serovars being significantly more likely to cause invasive disease in humans than others. Furthermore, while genomic analyses have advanced our understanding of the genetic diversity of these serovars, they have not been able to fully account for the observed clinical differences. One overarching challenge is that much of what is known about Salmonella's general biology and virulence strategies is concluded from studies examining a select few serovars, especially serovar Typhimurium. As targeted control strategies have been implemented to control select serovars, an increasing number of foodborne outbreaks involving serovars that are less frequently associated with human clinical illness are being detected. Harnessing what is known about the diversity of NTS serovars represents an important factor in achieving the ultimate goal of reducing salmonellosis-associated morbidity and mortality worldwide. In this review we summarize the current understanding of the differences and similarities among NTS serovars, highlighting the virulence mechanisms, genetic differences, and sources that characterize S. enterica diversity and contribute to its success as a foodborne pathogen.
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Affiliation(s)
- Rachel A. Cheng
- Department of Food Science, Cornell University, Ithaca, NY, United States
| | - Colleen R. Eade
- Department of Population Medicine and Diagnostic Sciences, Cornell University, Ithaca, NY, United States
- Department of Chemistry, University of North Carolina at Charlotte, Charlotte, NC, United States
| | - Martin Wiedmann
- Department of Food Science, Cornell University, Ithaca, NY, United States
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71
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McDowell MA, Byrne AM, Mylona E, Johnson R, Sagfors A, Crepin VF, Lea S, Frankel G. The S. Typhi effector StoD is an E3/E4 ubiquitin ligase which binds K48- and K63-linked diubiquitin. Life Sci Alliance 2019; 2:2/3/e201800272. [PMID: 31142637 PMCID: PMC6545606 DOI: 10.26508/lsa.201800272] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2018] [Revised: 05/03/2019] [Accepted: 05/07/2019] [Indexed: 11/24/2022] Open
Abstract
Salmonella Typhi is estimated to cause 100,000–200,000 deaths annually, yet its infection strategy remains elusive. This article reports of the first Typhi-specific effector, which has an E3/E4 ubiquitin ligase activity and can uniquely bind K48- and K63-linked diubiquitin. Salmonella enterica (e.g., serovars Typhi and Typhimurium) relies on translocation of effectors via type III secretion systems (T3SS). Specialization of typhoidal serovars is thought to be mediated via pseudogenesis. Here, we show that the Salmonella Typhi STY1076/t1865 protein, named StoD, a homologue of the enteropathogenic Escherichia coli/enterohemorrhagic E. coli/Citrobacter rodentium NleG, is a T3SS effector. The StoD C terminus (StoD-C) is a U-box E3 ubiquitin ligase, capable of autoubiquitination in the presence of multiple E2s. The crystal structure of the StoD N terminus (StoD-N) at 2.5 Å resolution revealed a ubiquitin-like fold. In HeLa cells expressing StoD, ubiquitin is redistributed into puncta that colocalize with StoD. Binding assays showed that StoD-N and StoD-C bind the same exposed surface of the β-sheet of ubiquitin, suggesting that StoD could simultaneously interact with two ubiquitin molecules. Consistently, StoD interacted with both K63- (KD = 5.6 ± 1 μM) and K48-linked diubiquitin (KD = 15 ± 4 μM). Accordingly, we report the first S. Typhi–specific T3SS effector. We suggest that StoD recognizes and ubiquitinates pre-ubiquitinated targets, thus subverting intracellular signaling by functioning as an E4 enzyme.
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Affiliation(s)
| | - Alexander Mp Byrne
- MRC Centre for Molecular Bacteriology and Infection, Department of Life Sciences, Imperial College, London, UK
| | - Elli Mylona
- MRC Centre for Molecular Bacteriology and Infection, Department of Life Sciences, Imperial College, London, UK
| | - Rebecca Johnson
- MRC Centre for Molecular Bacteriology and Infection, Department of Life Sciences, Imperial College, London, UK
| | - Agnes Sagfors
- MRC Centre for Molecular Bacteriology and Infection, Department of Life Sciences, Imperial College, London, UK
| | - Valerie F Crepin
- MRC Centre for Molecular Bacteriology and Infection, Department of Life Sciences, Imperial College, London, UK
| | - Susan Lea
- Sir William Dunn School of Pathology, University of Oxford, Oxford, UK
| | - Gad Frankel
- MRC Centre for Molecular Bacteriology and Infection, Department of Life Sciences, Imperial College, London, UK
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72
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Branchu P, Charity OJ, Bawn M, Thilliez G, Dallman TJ, Petrovska L, Kingsley RA. SGI-4 in Monophasic Salmonella Typhimurium ST34 Is a Novel ICE That Enhances Resistance to Copper. Front Microbiol 2019; 10:1118. [PMID: 31178839 PMCID: PMC6543542 DOI: 10.3389/fmicb.2019.01118] [Citation(s) in RCA: 45] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2019] [Accepted: 05/03/2019] [Indexed: 12/23/2022] Open
Abstract
A multi drug resistant Salmonella enterica 4,[5],12:i- of sequence type 34 (monophasic S. Typhimurium ST34) is a current pandemic clone associated with livestock, particularly pigs, and numerous outbreaks in the human population. A large genomic island, termed SGI-4, is present in the monophasic Typhimurium ST34 clade and absent from other S. Typhimurium strains. SGI-4 consists of 87 open reading frames including sil and pco genes previously implicated in resistance to copper (Cu) and silver, and multiple genes predicted to be involved in mobilization and transfer by conjugation. SGI-4 was excised from the chromosome, circularized, and transferred to recipient strains of S. Typhimurium at a frequency influenced by stress induced by mitomycin C, and oxygen tension. The presence of SGI-4 was associated with increased resistance to Cu, particularly but not exclusively under anaerobic conditions. The presence of silCBA genes, predicted to encode an RND family efflux pump that transports Cu from the periplasm to the external milieu, was sufficient to impart the observed enhanced resistance to Cu, above that commonly associated with S. Typhimurium isolates. The presence of these genes resulted in the absence of Cu-dependent induction of pco genes encoding multiple proteins linked to Cu resistance, also present on SGI-4, suggesting that the system effectively limits the Cu availability in the periplasm, but did not affect SodCI-dependent macrophage survival.
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Affiliation(s)
| | | | - Matt Bawn
- Quadram Institute Bioscience, Norwich, United Kingdom
| | | | - Timothy J. Dallman
- Gastrointestinal Bacteria Reference Unit, National Infection Service, Public Health England, London, United Kingdom
| | | | - Robert A. Kingsley
- Quadram Institute Bioscience, Norwich, United Kingdom
- School of Biological Sciences, University of East Anglia, Norwich, United Kingdom
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73
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Yong HS, Song SL, Eamsobhana P, Pasartvit A, Lim PE. Differential abundance and core members of the bacterial community associated with wild male Zeugodacus cucurbitae fruit flies (Insecta: Tephritidae) from three geographical regions of Southeast Asia. Mol Biol Rep 2019; 46:3765-3776. [PMID: 31012029 DOI: 10.1007/s11033-019-04818-3] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2019] [Accepted: 04/12/2019] [Indexed: 12/29/2022]
Abstract
Zeugodacus cucurbitae (Coquillet) is one of the most significant and widespread tephritid pest species of agricultural crops. This study reports the bacterial communities associated with Z. cucurbitae from three geographical regions in Southeast Asia (Thailand, Peninsular Malaysia, and Sarawak). The bacterial microbiota were investigated by targeted 16S rRNA gene (V3-V4 region) sequencing using the Illumina Mi-Seq platform. At 97% similarity and filtering at 0.001%, there were seven bacterial phyla and unassigned bacteria, comprising 11 classes, 23 orders, 39 families and 67 genera. The bacterial diversity and richness varied within and among the samples from the three geographical regions. Five phyla were detected for the Sarawak sample, and six each for the Thailand and Peninsular Malaysia samples. Four phyla-Actinobacteria, Bacteroidetes, Firmicutes, and Proteobacteria-were represented in all the fruit fly specimens, forming the core members of the bacterial community. Proteobacteria was the predominant phylum, followed by Bacteroidetes, Firmicutes, and Actinobacteria. Fifty-three genera were represented in the Thailand sample, 56 in the Peninsular Malaysia sample, and 55 in the Sarawak sample. Forty-two genera were present in all the three geographical regions. The predominant core members were order Enterobacteriales (Proeteobacteria), and family Enterobacteriaceae (Enterobacteriales). Klebsiella (Enterobacteriaceae) was the predominant genus and K. oxytoca the predominant species with all specimens having > 10% relative abundance. The results indicate the presence of a great diversity as well as core members of the bacterial community associated with different populations of Z. cucurbitae.
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Affiliation(s)
- Hoi-Sen Yong
- Institute of Biological Sciences, Faculty of Science, University of Malaya, 50603, Kuala Lumpur, Malaysia
| | - Sze-Looi Song
- Institute of Ocean and Earth Sciences, University of Malaya, 50603, Kuala Lumpur, Malaysia. .,China-ASEAN College of Marine Sciences, Xiamen University Malaysia, Jalan Sunsuria, Bandar Sunsuria, 43900, Sepang, Selangor, Malaysia.
| | - Praphathip Eamsobhana
- Department of Parasitology, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand
| | - Anchana Pasartvit
- Department of Disease Control, Ministry of Public Health, Nonthaburi, Thailand
| | - Phaik-Eem Lim
- Institute of Ocean and Earth Sciences, University of Malaya, 50603, Kuala Lumpur, Malaysia
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74
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Patel S, Wall DM, Castillo A, McCormick BA. Caspase-3 cleavage of Salmonella type III secreted effector protein SifA is required for localization of functional domains and bacterial dissemination. Gut Microbes 2019; 10:172-187. [PMID: 30727836 PMCID: PMC6546311 DOI: 10.1080/19490976.2018.1506668] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
SifA is a bi-functional Type III Secretion System (T3SS) effector protein that plays an important role in Salmonella virulence. The N-terminal domain of SifA binds SifA-Kinesin-Interacting-Protein (SKIP), and via an interaction with kinesin, forms tubular membrane extensions called Sif filaments (Sifs) that emanate from the Salmonella Containing Vacuole (SCV). The C-terminal domain of SifA harbors a WxxxE motif that functions to mimic active host cell GTPases. Taken together, SifA functions in inducing endosomal tubulation in order to maintain the integrity of the SCV and promote bacterial dissemination. Since SifA performs multiple, unrelated functions, the objective of this study was to determine how each functional domain of SifA becomes processed. Our work demonstrates that a linker region containing a caspase-3 cleavage motif separates the two functional domains of SifA. To test the hypothesis that processing of SifA by caspase-3 at this particular site is required for function and proper localization of the effector protein domains, we developed two tracking methods to analyze the intracellular localization of SifA. We first adapted a fluorescent tag called phiLOV that allowed for type-III secretion system (T3SS) mediated delivery of SifA and observation of its intracellular colocalization with caspase-3. Additionally, we created a dual-tagging strategy that permitted tracking of each of the SifA functional domains following caspase-3 cleavage to different subcellular locations. The results of this study reveal that caspase-3 cleavage of SifA is required for the proper localization of functional domains and bacterial dissemination. Considering the importance of these events in Salmonella pathogenesis, we conclude that caspase-3 cleavage of effector proteins is a more broadly applicable effector processing mechanism utilized by Salmonella to invade and persist during infection.
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Affiliation(s)
- Samir Patel
- Department of Microbiology and Physiological Systems, University of Massachusetts Medical School, Worcester, MA, USA,CONTACT Beth McCormick Department of Microbiology and Physiological Systems, University of Massachusetts Medical School, 368 Plantation Street AS8-2011, Worcester, MA 01605, USA
| | - Daniel M. Wall
- Institute of Infection, Immunity and Inflammation, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, UK
| | - Antonio Castillo
- Department of Microbiology and Physiological Systems, University of Massachusetts Medical School, Worcester, MA, USA
| | - Beth A. McCormick
- Department of Microbiology and Physiological Systems, University of Massachusetts Medical School, Worcester, MA, USA
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75
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Bao H, Zhao JH, Zhu S, Wang S, Zhang J, Wang XY, Hua B, Liu C, Liu H, Liu SL. Genetic diversity and evolutionary features of type VI secretion systems in Salmonella. Future Microbiol 2019; 14:139-154. [PMID: 30672329 DOI: 10.2217/fmb-2018-0260] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
AIM Type VI secretion systems (T6SS) play key roles in bacterial pathogenesis, but their evolutionary features remain largely unclear. In this study, we conducted systematic comparisons among the documented T6SSs in Salmonella and determined their structural diversity, phylogenetic distribution and lineage-specific properties. MATERIALS & METHODS We screened 295 Salmonella genomes for 13 T6SS core components by hidden Markov models and identified 363 T6SS clusters covering types i1, i2, i3 and i4a. RESULTS Type i3 and i4a T6SSs were restricted to Salmonella enterica subspecies enterica and Salmonella bongori, respectively. whereas type i2 T6SSs were conserved between S. enterica subspecies, arizonae and diarizonae. S. enterica subspecies salamae, indica and houtenae harbored only type i1 T6SSs, which had wide distribution and high sequence diversity. CONCLUSION The diverse Salmonella T6SSs have undergone purifying selection pressures during the bacterial evolution and may be involved in host adaptation.
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Affiliation(s)
- Hongxia Bao
- Systemomics Center, College of Pharmacy & Genomics Research Center, Harbin Medical University, Harbin, PR China.,HMU-UCCSM Centre for Infection & Genomics, Harbin Medical University, Harbin, PR China.,Translational Medicine Research & Cooperation Center of Northern China, Heilongjiang Academy of Medical Sciences, Harbin, PR China
| | - Jian-Hua Zhao
- Systemomics Center, College of Pharmacy & Genomics Research Center, Harbin Medical University, Harbin, PR China.,HMU-UCCSM Centre for Infection & Genomics, Harbin Medical University, Harbin, PR China.,Translational Medicine Research & Cooperation Center of Northern China, Heilongjiang Academy of Medical Sciences, Harbin, PR China
| | - Songling Zhu
- Systemomics Center, College of Pharmacy & Genomics Research Center, Harbin Medical University, Harbin, PR China.,HMU-UCCSM Centre for Infection & Genomics, Harbin Medical University, Harbin, PR China.,Translational Medicine Research & Cooperation Center of Northern China, Heilongjiang Academy of Medical Sciences, Harbin, PR China
| | - Shuang Wang
- Department of Biopharmaceutical Sciences, College of Pharmacy, Harbin Medical University, Harbin, PR China
| | - Jianjuan Zhang
- Systemomics Center, College of Pharmacy & Genomics Research Center, Harbin Medical University, Harbin, PR China.,HMU-UCCSM Centre for Infection & Genomics, Harbin Medical University, Harbin, PR China.,Translational Medicine Research & Cooperation Center of Northern China, Heilongjiang Academy of Medical Sciences, Harbin, PR China
| | - Xiao-Yu Wang
- Systemomics Center, College of Pharmacy & Genomics Research Center, Harbin Medical University, Harbin, PR China.,HMU-UCCSM Centre for Infection & Genomics, Harbin Medical University, Harbin, PR China.,Translational Medicine Research & Cooperation Center of Northern China, Heilongjiang Academy of Medical Sciences, Harbin, PR China
| | - Bing Hua
- Systemomics Center, College of Pharmacy & Genomics Research Center, Harbin Medical University, Harbin, PR China.,HMU-UCCSM Centre for Infection & Genomics, Harbin Medical University, Harbin, PR China.,Translational Medicine Research & Cooperation Center of Northern China, Heilongjiang Academy of Medical Sciences, Harbin, PR China
| | - Chang Liu
- Systemomics Center, College of Pharmacy & Genomics Research Center, Harbin Medical University, Harbin, PR China.,HMU-UCCSM Centre for Infection & Genomics, Harbin Medical University, Harbin, PR China.,Translational Medicine Research & Cooperation Center of Northern China, Heilongjiang Academy of Medical Sciences, Harbin, PR China
| | - Huidi Liu
- Systemomics Center, College of Pharmacy & Genomics Research Center, Harbin Medical University, Harbin, PR China.,HMU-UCCSM Centre for Infection & Genomics, Harbin Medical University, Harbin, PR China.,Translational Medicine Research & Cooperation Center of Northern China, Heilongjiang Academy of Medical Sciences, Harbin, PR China
| | - Shu-Lin Liu
- Systemomics Center, College of Pharmacy & Genomics Research Center, Harbin Medical University, Harbin, PR China.,HMU-UCCSM Centre for Infection & Genomics, Harbin Medical University, Harbin, PR China.,Translational Medicine Research & Cooperation Center of Northern China, Heilongjiang Academy of Medical Sciences, Harbin, PR China.,Department of Microbiology, Immunology & Infectious Diseases, University of Calgary, Calgary, T2N 1N4, Canada
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76
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Chatterjee R, Shreenivas MM, Sunil R, Chakravortty D. Enteropathogens: Tuning Their Gene Expression for Hassle-Free Survival. Front Microbiol 2019; 9:3303. [PMID: 30687282 PMCID: PMC6338047 DOI: 10.3389/fmicb.2018.03303] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2018] [Accepted: 12/19/2018] [Indexed: 12/27/2022] Open
Abstract
Enteropathogenic bacteria have been the cause of the majority of foodborne illnesses. Much of the research has been focused on elucidating the mechanisms by which these pathogens evade the host immune system. One of the ways in which they achieve the successful establishment of a niche in the gut microenvironment and survive is by a chain of elegantly regulated gene expression patterns. Studies have shown that this process is very elaborate and is also regulated by several factors. Pathogens like, enteropathogenic Escherichia coli (EPEC), Salmonella Typhimurium, Shigella flexneri, Yersinia sp. have been seen to employ various regulated gene expression strategies. These include toxin-antitoxin systems, quorum sensing systems, expression controlled by nucleoid-associated proteins (NAPs), several regulons and operons specific to these pathogens. In the following review, we have tried to discuss the common gene regulatory systems of enteropathogenic bacteria as well as pathogen-specific regulatory mechanisms.
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Affiliation(s)
- Ritika Chatterjee
- Department of Microbiology and Cell Biology, Indian Institute of Science, Bengaluru, India
- Division of Biological Sciences, Indian Institute of Science, Bengaluru, India
| | - Meghanashree M. Shreenivas
- Department of Microbiology and Cell Biology, Indian Institute of Science, Bengaluru, India
- Division of Biological Sciences, Indian Institute of Science, Bengaluru, India
- Undergraduate Studies, Indian Institute of Science, Bengaluru, India
| | - Rohith Sunil
- Department of Microbiology and Cell Biology, Indian Institute of Science, Bengaluru, India
- Division of Biological Sciences, Indian Institute of Science, Bengaluru, India
- Undergraduate Studies, Indian Institute of Science, Bengaluru, India
| | - Dipshikha Chakravortty
- Department of Microbiology and Cell Biology, Indian Institute of Science, Bengaluru, India
- Division of Biological Sciences, Indian Institute of Science, Bengaluru, India
- Centre for Biosystems Science and Engineering, Indian Institute of Science, Bengaluru, India
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77
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Elder JR, Paul NC, Burin R, Guard J, Shah DH. Genomic organization and role of SPI-13 in nutritional fitness of Salmonella. Int J Med Microbiol 2018; 308:1043-1052. [PMID: 30466554 DOI: 10.1016/j.ijmm.2018.10.004] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2018] [Revised: 09/21/2018] [Accepted: 10/10/2018] [Indexed: 02/07/2023] Open
Abstract
Salmonella pathogenicity island 13 (SPI-13) contributes to the virulence of Salmonella. The majority of the SPI-13 genes encode proteins putatively involved in bacterial metabolism, however, their functions largely remain uncharacterized. It is currently unknown if SPI-13 contributes to metabolic fitness of Salmonella and, if so, what are the metabolic substrates for the protein encoded by genes within SPI-13. We employed Phenotype Microarray (Biolog, USA) to compare the metabolic properties of SPI-13 deficient mutant (ΔSPI-13) and the WT parent strain of non-typhoidal Salmonella enterica sub sp. enterica serovar Enteritidis (S. Enteritidis). The results of Phenotype Microarray revealed that SPI-13 is required for efficient utilization of two micronutrients, namely, d-glucuronic acid (DGA) and tyramine (TYR), as sole sources of carbon and/or nitrogen. By systematic deletion of the individual gene(s), we identified specific genes within SPI-13 that are required for efficient utilization of DGA (SEN2977-80) and TYR (SEN2967 and SEN2971-72) as sole nutrient sources. The results show that SPI-13 mediated DGA and TYR metabolic pathways afford nutritional fitness to S. Enteritidis. Comparative genomics analysis of the SPI-13 locus from 247 Salmonella strains belonging to 57 different serovars revealed that SPI-13 genes specifically involved in the metabolism of DGA and TYR are highly conserved in Salmonella enterica. Because DGA and TYR are naturally present as metabolic byproducts in the gastrointestinal tract and other host tissues, we propose a metabolic model that shows that the role of SPI-13 mediated DGA and TYR metabolism in the nutritional fitness of Salmonella is likely linked to nutritional virulence of this pathogen.
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Affiliation(s)
- Jacob R Elder
- Department of Microbiology and Pathology, College of Veterinary Medicine, Washington State University, Pullman, Washington, 99164-7040, USA
| | - Narayan C Paul
- Department of Microbiology and Pathology, College of Veterinary Medicine, Washington State University, Pullman, Washington, 99164-7040, USA
| | - Raquel Burin
- Department of Microbiology and Pathology, College of Veterinary Medicine, Washington State University, Pullman, Washington, 99164-7040, USA
| | - Jean Guard
- Egg Quality and Safety Research Unit, Agriculture Research Service, United StatesDepartment of Agriculture, Athens, GA, 30605, USA
| | - Devendra H Shah
- Department of Microbiology and Pathology, College of Veterinary Medicine, Washington State University, Pullman, Washington, 99164-7040, USA; Paul Allen School for Global Animal Health, College of Veterinary Medicine, Washington State University, Pullman, Washington, 99164-7040, USA.
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78
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Roche SM, Holbert S, Trotereau J, Schaeffer S, Georgeault S, Virlogeux-Payant I, Velge P. Salmonella Typhimurium Invalidated for the Three Currently Known Invasion Factors Keeps Its Ability to Invade Several Cell Models. Front Cell Infect Microbiol 2018; 8:273. [PMID: 30148118 PMCID: PMC6095967 DOI: 10.3389/fcimb.2018.00273] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2018] [Accepted: 07/23/2018] [Indexed: 12/25/2022] Open
Abstract
To establish an infection, Salmonella has to interact with eukaryotic cells. Invasion of non-phagocytic cells (i.e., epithelial, fibroblast and endothelial cells) involves either a trigger or a zipper mechanism mediated by the T3SS-1 or the invasin Rck, respectively. Another outer membrane protein, PagN, was also implicated in the invasion. However, other unknown invasion factors have been previously suggested. Our goal was to evaluate the invasion capability of a Salmonella Typhimurium strain invalidated for the three known invasion factors. Non-phagocytic cell lines of several animal origins were tested in a gentamicin protection assay. In most cells, we observed a drastic decrease in the invasion rate between the wild-type and the triple mutant. However, in five cell lines, the triple mutant invaded cells at a similarly high level to the wild-type, suggesting the existence of unidentified invasion factors. For the wild-type and the triple mutant, scanning-electron microscopy, confocal imaging and use of biochemical inhibitors confirmed their cellular uptake and showed a zipper-like mechanism of internalization involving both clathrin- and non-clathrin-dependent pathways. Despite a functional T3SS-1, the wild-type bacteria seemed to use the same entry route as the mutant in our cell model. All together, these results demonstrate the existence of unknown Salmonella invasion factors, which require further characterization.
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Affiliation(s)
- Sylvie M. Roche
- ISP, Institut National de la Recherche Agronomique (INRA), UMR 1282, Université de Tours, Paris, France
| | - Sébastien Holbert
- ISP, Institut National de la Recherche Agronomique (INRA), UMR 1282, Université de Tours, Paris, France
| | - Jérôme Trotereau
- ISP, Institut National de la Recherche Agronomique (INRA), UMR 1282, Université de Tours, Paris, France
| | - Samantha Schaeffer
- ISP, Institut National de la Recherche Agronomique (INRA), UMR 1282, Université de Tours, Paris, France
- INSERM UMR 1162, Institut de Génétique Moléculaire, Paris, France
| | - Sonia Georgeault
- Plateforme des Microscopies, Université et CHRU de Tours, Tours, France
| | - Isabelle Virlogeux-Payant
- ISP, Institut National de la Recherche Agronomique (INRA), UMR 1282, Université de Tours, Paris, France
| | - Philippe Velge
- ISP, Institut National de la Recherche Agronomique (INRA), UMR 1282, Université de Tours, Paris, France
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79
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Salmonella-containing vacuole development in avian cells and characteristic of cigR in Salmonella enterica serovar Pullorum replication within macrophages. Vet Microbiol 2018; 223:65-71. [PMID: 30173754 DOI: 10.1016/j.vetmic.2018.07.013] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2018] [Revised: 07/16/2018] [Accepted: 07/18/2018] [Indexed: 01/03/2023]
Abstract
Salmonella enterica serovar Pullorum (S. Pullorum) is one of the host-restricted serotypes causing systemic infection in poultry. Survival in macrophages is one of the mechanisms underlying the persistent infection of S. Pullorum in hosts. Formation of Salmonella-containing vacuole (SCV) is essential for bacteria to be concealed in macrophages. In this study, confocal microscopy was applied to detect the SCV development by S. Pullorum in the chicken hepatocellular carcinoma cell line LMH and the macrophage cell line HD-11, respectively. The results showed that macrophages were more appropriate for the SCV maturation during S. Pullorum infection compared to epithelial cells. We evaluated the role of the CigR effector protein in the formation of SCVs. CigR is a membrane-binding protein, which is one of the type III secretion system 2 (T3SS2) effectors encoded within Salmonella pathogenicity island 3 (SPI3). The deletion of cigR in S. Typhimurium and S. Pullorum enhanced bacterial virulence to both mice and chickens. To analyze the influence of CigR on the SCV development during S. Pullorum infection, this study compared the formation of SCVs by using S. Pullorum C79-13 and the cigR deleted strain C79-13ΔcigR. Compared to the wild type strain, the loss of cigR gene in strain C79-13ΔcigR caused a four-fold increase in the recruitment ability of the SCV marker protein Rab7 in infected macrophages after 30 min, 5 h, and 16 h post-infection. In addition, infection and proliferation of strain C79-13ΔcigR in the avian macrophage cell line HD-11 was higher than that of the wild type strain. Our findings suggest that CigR is an anti-virulence effector inhibiting replication of S. Pullorum and SCV development in macrophages.
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80
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Jiang X, Li X, Sun S, Jiang L. The transcriptional regulator VarN contributes to Salmonella Typhimurium growth in macrophages and virulence in mice. Res Microbiol 2018; 169:214-221. [DOI: 10.1016/j.resmic.2018.03.003] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2018] [Revised: 03/21/2018] [Accepted: 03/29/2018] [Indexed: 11/30/2022]
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81
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Yin J, Xia J, Tao M, Xu L, Li Q, Geng S, Jiao X. Construction and characterization of a cigR deletion mutant of Salmonella enterica serovar Pullorum. Avian Pathol 2018; 45:569-75. [PMID: 27163262 DOI: 10.1080/03079457.2016.1187708] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
Salmonella enterica serovar Pullorum (S. Pullorum) is the causative agent of pullorum disease (PD) and results in severe economic losses to the poultry industry. As a Salmonella type III secretion system 2 (T3SS2) effector and predicted membrane protein, CigR is encoded by the cigR gene within Salmonella pathogenicity island 3 (SPI3). In order to research the influence of the cigR gene on S. Pullorum, a cigR mutant of S. Pullorum S06004 was constructed by the lambda Red recombination system, and then its characterization was analysed. Lack of cigR did not affect the growth and biochemical properties, but resulted in decreased biofilm formation. The mutant strain was stable with the deletion of the cigR gene. Macrophage infection assay and in vivo competition assay showed that the mutant strain increased the replication and/or survival ability in the HD11 cell line and in chickens compared to that of the parent strain, the median lethal dose (LD50) of the mutant strain was one-fifth of the parent strain for 2-day-old chickens when injected intramuscularly. These results demonstrate CigR plays roles in biofilm formation and pathogenicity of S. Pullorum, deletion of cigR can significantly decrease biofilm formation and significantly increase virulence.
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Affiliation(s)
- Junlei Yin
- a Jiangsu Key Laboratory of Zoonosis, Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses , Yangzhou University , Yangzhou , People's Republic of China
| | - Jie Xia
- a Jiangsu Key Laboratory of Zoonosis, Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses , Yangzhou University , Yangzhou , People's Republic of China
| | - Mingxin Tao
- a Jiangsu Key Laboratory of Zoonosis, Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses , Yangzhou University , Yangzhou , People's Republic of China
| | - Lijuan Xu
- a Jiangsu Key Laboratory of Zoonosis, Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses , Yangzhou University , Yangzhou , People's Republic of China
| | - Qiuchun Li
- a Jiangsu Key Laboratory of Zoonosis, Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses , Yangzhou University , Yangzhou , People's Republic of China
| | - Shizhong Geng
- a Jiangsu Key Laboratory of Zoonosis, Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses , Yangzhou University , Yangzhou , People's Republic of China
| | - Xinan Jiao
- a Jiangsu Key Laboratory of Zoonosis, Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses , Yangzhou University , Yangzhou , People's Republic of China
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82
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Lamas A, Miranda JM, Regal P, Vázquez B, Franco CM, Cepeda A. A comprehensive review of non-enterica subspecies of Salmonella enterica. Microbiol Res 2018; 206:60-73. [DOI: 10.1016/j.micres.2017.09.010] [Citation(s) in RCA: 109] [Impact Index Per Article: 15.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2017] [Revised: 09/22/2017] [Accepted: 09/26/2017] [Indexed: 12/11/2022]
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83
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Barquist L, Westermann AJ, Vogel J. Molecular phenotyping of infection-associated small non-coding RNAs. Philos Trans R Soc Lond B Biol Sci 2017; 371:rstb.2016.0081. [PMID: 27672158 DOI: 10.1098/rstb.2016.0081] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/19/2016] [Indexed: 02/07/2023] Open
Abstract
Infection is a complicated balance, with both pathogen and host struggling to tilt the result in their favour. Bacterial infection biology has relied on forward genetics for many of its advances, defining phenotype in terms of replication in model systems. However, many known virulence factors fail to produce robust phenotypes, particularly in the systems most amenable to genetic manipulation, such as cell-culture models. This has particularly been limiting for the study of the bacterial regulatory small RNAs (sRNAs) in infection. We argue that new sequencing-based technologies can work around this problem by providing a 'molecular phenotype', defined in terms of the specific transcriptional dysregulation in the infection system induced by gene deletion. We illustrate this using the example of our recent study of the PinT sRNA using dual RNA-seq, that is, simultaneous RNA sequencing of host and pathogen during infection. We additionally discuss how other high-throughput technologies, in particular genetic interaction mapping using transposon insertion sequencing, may be used to further dissect molecular phenotypes. We propose a strategy for how high-throughput technologies can be integrated in the study of non-coding regulators as well as bacterial virulence factors, enhancing our ability to rapidly generate hypotheses with regards to their function.This article is part of the themed issue 'The new bacteriology'.
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Affiliation(s)
- Lars Barquist
- RNA Biology Group, Institute for Molecular Infection Biology, University of Würzburg, Josef-Schneider-Straße 2/D15, 97080 Würzburg, Germany
| | - Alexander J Westermann
- RNA Biology Group, Institute for Molecular Infection Biology, University of Würzburg, Josef-Schneider-Straße 2/D15, 97080 Würzburg, Germany
| | - Jörg Vogel
- RNA Biology Group, Institute for Molecular Infection Biology, University of Würzburg, Josef-Schneider-Straße 2/D15, 97080 Würzburg, Germany Research Centre for Infectious Diseases (ZINF), University of Würzburg, 97070 Würzburg, Germany
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84
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Domesle KJ, Yang Q, Hammack TS, Ge B. Validation of a Salmonella loop-mediated isothermal amplification assay in animal food. Int J Food Microbiol 2017; 264:63-76. [PMID: 29121500 DOI: 10.1016/j.ijfoodmicro.2017.10.020] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2017] [Revised: 10/12/2017] [Accepted: 10/16/2017] [Indexed: 12/18/2022]
Abstract
Loop-mediated isothermal amplification (LAMP) has emerged as a promising alternative to PCR for pathogen detection in food testing and clinical diagnostics. This study aimed to validate a Salmonella LAMP method run on both turbidimetry (LAMP I) and fluorescence (LAMP II) platforms in representative animal food commodities. The U.S. Food and Drug Administration (FDA)'s culture-based Bacteriological Analytical Manual (BAM) method was used as the reference method and a real-time quantitative PCR (qPCR) assay was also performed. The method comparison study followed the FDA's microbiological methods validation guidelines, which align well with those from the AOAC International and ISO. Both LAMP assays were 100% specific among 300 strains (247 Salmonella of 185 serovars and 53 non-Salmonella) tested. The detection limits ranged from 1.3 to 28 cells for six Salmonella strains of various serovars. Six commodities consisting of four animal feed items (cattle feed, chicken feed, horse feed, and swine feed) and two pet food items (dry cat food and dry dog food) all yielded satisfactory results. Compared to the BAM method, the relative levels of detection (RLODs) for LAMP I ranged from 0.317 to 1 with a combined value of 0.610, while those for LAMP II ranged from 0.394 to 1.152 with a combined value of 0.783, which all fell within the acceptability limit (2.5) for an unpaired study. This also suggests that LAMP was more sensitive than the BAM method at detecting low-level Salmonella contamination in animal food and results were available 3days sooner. The performance of LAMP on both platforms was comparable to that of qPCR but notably faster, particularly LAMP II. Given the importance of Salmonella in animal food safety, the LAMP assays validated in this study holds great promise as a rapid, reliable, and robust method for routine screening of Salmonella in these commodities.
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Affiliation(s)
- Kelly J Domesle
- Division of Animal and Food Microbiology, Office of Research, Center for Veterinary Medicine, U.S. Food and Drug Administration, 8401 Muirkirk Road, Laurel, MD 20708, USA
| | - Qianru Yang
- Division of Animal and Food Microbiology, Office of Research, Center for Veterinary Medicine, U.S. Food and Drug Administration, 8401 Muirkirk Road, Laurel, MD 20708, USA
| | - Thomas S Hammack
- Division of Microbiology, Office of Regulatory Science, Center for Food Safety and Applied Nutrition, U.S. Food and Drug Administration, 5001 Campus Drive, College Park, MD 20740, USA
| | - Beilei Ge
- Division of Animal and Food Microbiology, Office of Research, Center for Veterinary Medicine, U.S. Food and Drug Administration, 8401 Muirkirk Road, Laurel, MD 20708, USA.
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85
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Ilyas B, Tsai CN, Coombes BK. Evolution of Salmonella-Host Cell Interactions through a Dynamic Bacterial Genome. Front Cell Infect Microbiol 2017; 7:428. [PMID: 29034217 PMCID: PMC5626846 DOI: 10.3389/fcimb.2017.00428] [Citation(s) in RCA: 84] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2017] [Accepted: 09/19/2017] [Indexed: 11/13/2022] Open
Abstract
Salmonella Typhimurium has a broad arsenal of genes that are tightly regulated and coordinated to facilitate adaptation to the various host environments it colonizes. The genome of Salmonella Typhimurium has undergone multiple gene acquisition events and has accrued changes in non-coding DNA that have undergone selection by regulatory evolution. Together, at least 17 horizontally acquired pathogenicity islands (SPIs), prophage-associated genes, and changes in core genome regulation contribute to the virulence program of Salmonella. Here, we review the latest understanding of these elements and their contributions to pathogenesis, emphasizing the regulatory circuitry that controls niche-specific gene expression. In addition to an overview of the importance of SPI-1 and SPI-2 to host invasion and colonization, we describe the recently characterized contributions of other SPIs, including the antibacterial activity of SPI-6 and adhesion and invasion mediated by SPI-4. We further discuss how these fitness traits have been integrated into the regulatory circuitry of the bacterial cell through cis-regulatory evolution and by a careful balance of silencing and counter-silencing by regulatory proteins. Detailed understanding of regulatory evolution within Salmonella is uncovering novel aspects of infection biology that relate to host-pathogen interactions and evasion of host immunity.
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Affiliation(s)
- Bushra Ilyas
- Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, ON, Canada.,Michael DeGroote Institute for Infectious Disease Research, McMaster University, Hamilton, ON, Canada
| | - Caressa N Tsai
- Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, ON, Canada.,Michael DeGroote Institute for Infectious Disease Research, McMaster University, Hamilton, ON, Canada
| | - Brian K Coombes
- Michael DeGroote Institute for Infectious Disease Research, McMaster University, Hamilton, ON, Canada
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86
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Comparative Genomics of Bacillus thuringiensis Reveals a Path to Specialized Exploitation of Multiple Invertebrate Hosts. mBio 2017; 8:mBio.00822-17. [PMID: 28790205 PMCID: PMC5550751 DOI: 10.1128/mbio.00822-17] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Understanding the genetic basis of host shifts is a key genomic question for pathogen and parasite biology. The Bacillus cereus group, which encompasses Bacillus thuringiensis and Bacillus anthracis, contains pathogens that can infect insects, nematodes, and vertebrates. Since the target range of the essential virulence factors (Cry toxins) and many isolates is well known, this group presents a powerful system for investigating how pathogens can diversify and adapt to phylogenetically distant hosts. Specialization to exploit insects occurs at the level of the major clade and is associated with substantial changes in the core genome, and host switching between insect orders has occurred repeatedly within subclades. The transfer of plasmids with linked cry genes may account for much of the adaptation to particular insect orders, and network analysis implies that host specialization has produced strong associations between key toxin genes with similar targets. Analysis of the distribution of plasmid minireplicons shows that plasmids with orf156 and orf157, which carry genes encoding toxins against Lepidoptera or Diptera, were contained only by B. thuringiensis in the specialized insect clade (clade 2), indicating that tight genome/plasmid associations have been important in adaptation to invertebrate hosts. Moreover, the accumulation of multiple virulence factors on transposable elements suggests that cotransfer of diverse virulence factors is advantageous in terms of expanding the insecticidal spectrum, overcoming insect resistance, or through gains in pathogenicity via synergistic interactions between toxins.IMPORTANCE Population genomics have provided many new insights into the formation, evolution, and dynamics of bacterial pathogens of humans and other higher animals, but these pathogens usually have very narrow host ranges. As a pathogen of insects and nematodes, Bacillus thuringiensis, which produces toxins showing toxicity to many orders of insects and other invertebrates, can be used as a model to study the evolution of pathogens with wide host ranges. Phylogenomic analysis revealed that host specialization and switching occur at the level of the major clade and subclade, respectively. A toxin gene co-occurrence network indicates that multiple toxins with similar targets were accumulated by the same cell in the whole species. This accumulation may be one of the strategies that B. thuringiensis has used to fight against host resistance. This kind of formation and evolution of pathogens represents a different path used against multiple invertebrate hosts from that used against higher animals.
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87
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Whole-Genome Shotgun Sequence of Salmonella bongori, First Isolated in Northwestern Italy. GENOME ANNOUNCEMENTS 2017; 5:5/27/e00560-17. [PMID: 28684570 PMCID: PMC5502851 DOI: 10.1128/genomea.00560-17] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
This study describes the whole-genome shotgun sequence of Salmonella bongori 48:z35:–, originally isolated from a 1-year-old symptomatic patient in northwest Italy, a typically nonendemic area. The draft genome sequence contained 4.56 Mbp and the G+C content was 51.27%.
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88
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Hu Y, Huang H, Cheng X, Shu X, White AP, Stavrinides J, Köster W, Zhu G, Zhao Z, Wang Y. A global survey of bacterial type III secretion systems and their effectors. Environ Microbiol 2017; 19:3879-3895. [DOI: 10.1111/1462-2920.13755] [Citation(s) in RCA: 50] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2016] [Accepted: 04/04/2017] [Indexed: 11/27/2022]
Affiliation(s)
- Yueming Hu
- Department of Cell Biology and Genetics, School of Basic Medical Sciences; Shenzhen University Health Science Center; Shenzhen 518060 P.R. China
| | - He Huang
- MOH Key Laboratory of Systems Biology of Pathogens, Institute of Pathogen Biology; Chinese Academy of Medical Sciences & Peking Union Medical College; Beijing China
| | - Xi Cheng
- Department of Cell Biology and Genetics, School of Basic Medical Sciences; Shenzhen University Health Science Center; Shenzhen 518060 P.R. China
| | - Xingsheng Shu
- Department of Cell Biology and Genetics, School of Basic Medical Sciences; Shenzhen University Health Science Center; Shenzhen 518060 P.R. China
| | - Aaron P. White
- Vaccine and Infectious Disease Organization; University of Saskatchewan; Saskatoon SK Canada
| | | | - Wolfgang Köster
- Vaccine and Infectious Disease Organization; University of Saskatchewan; Saskatoon SK Canada
| | - Guoqiang Zhu
- College of Veterinary Medicine; Yangzhou University; Yangzhou China
| | - Zhendong Zhao
- MOH Key Laboratory of Systems Biology of Pathogens, Institute of Pathogen Biology; Chinese Academy of Medical Sciences & Peking Union Medical College; Beijing China
| | - Yejun Wang
- Department of Cell Biology and Genetics, School of Basic Medical Sciences; Shenzhen University Health Science Center; Shenzhen 518060 P.R. China
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89
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Newson JPM. Salmonella in Australia: understanding and controlling infection. MICROBIOLOGY AUSTRALIA 2017. [DOI: 10.1071/ma17044] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
The bacterium Salmonella causes a spectrum of foodborne diseases ranging from acute gastroenteritis to systemic infections, and represents a significant burden of disease globally. In Australia, Salmonella is frequently associated with outbreaks and is a leading cause of foodborne illness, which results in a significant medical and economic burden. Salmonella infection involves colonisation of the small intestine, where the bacteria invades host cells and establishes an intracellular infection. To survive within host cells, Salmonella employs type-three secretion systems to deliver bacterial effector proteins into the cytoplasm of host cells. These bacterial effectors seek out and modify specific host proteins, disrupting host processes such as cell signalling, intracellular trafficking, and programmed cell death. This strategy of impairing host cells allows Salmonella to establish a replicative niche within the cell, where they can replicate to high numbers before escaping to infect neighbouring cells, or be transmitted to new hosts. While the importance of effector protein translocation to infection is well established, our understanding of many effector proteins remains incomplete. Many Salmonella effectors have unknown function and unknown roles during infection. A greater understanding of how Salmonella manipulates host cells during infection will lead to improved strategies to prevent, control, and eliminate disease. Further, studying effector proteins can be a useful means for exploring host cell biology and elucidating the details of host cell signalling.
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90
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Martínez-Flores I, Pérez-Morales D, Sánchez-Pérez M, Paredes CC, Collado-Vides J, Salgado H, Bustamante VH. In silico clustering of Salmonella global gene expression data reveals novel genes co-regulated with the SPI-1 virulence genes through HilD. Sci Rep 2016; 6:37858. [PMID: 27886269 PMCID: PMC5122947 DOI: 10.1038/srep37858] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2016] [Accepted: 11/02/2016] [Indexed: 01/04/2023] Open
Abstract
A wide variety of Salmonella enterica serovars cause intestinal and systemic infections to humans and animals. Salmonella Patogenicity Island 1 (SPI-1) is a chromosomal region containing 39 genes that have crucial virulence roles. The AraC-like transcriptional regulator HilD, encoded in SPI-1, positively controls the expression of the SPI-1 genes, as well as of several other virulence genes located outside SPI-1. In this study, we applied a clustering method to the global gene expression data of S. enterica serovar Typhimurium from the COLOMBOS database; thus genes that show an expression pattern similar to that of SPI-1 genes were selected. This analysis revealed nine novel genes that are co-expressed with SPI-1, which are located in different chromosomal regions. Expression analyses and protein-DNA interaction assays showed regulation by HilD for six of these genes: gtgE, phoH, sinR, SL1263 (lpxR) and SL4247 were regulated directly, whereas SL1896 was regulated indirectly. Interestingly, phoH is an ancestral gene conserved in most of bacteria, whereas the other genes show characteristics of genes acquired by Salmonella. A role in virulence has been previously demonstrated for gtgE, lpxR and sinR. Our results further expand the regulon of HilD and thus identify novel possible Salmonella virulence genes.
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Affiliation(s)
- Irma Martínez-Flores
- Programa de Genómica Computacional, Centro de Ciencias Genómicas, Universidad Nacional Autónoma de México, Cuernavaca, Morelos 62210, México
| | - Deyanira Pérez-Morales
- Departamento de Microbiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Morelos 62210, México
| | - Mishael Sánchez-Pérez
- Programa de Genómica Computacional, Centro de Ciencias Genómicas, Universidad Nacional Autónoma de México, Cuernavaca, Morelos 62210, México
| | - Claudia C Paredes
- Departamento de Microbiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Morelos 62210, México
| | - Julio Collado-Vides
- Programa de Genómica Computacional, Centro de Ciencias Genómicas, Universidad Nacional Autónoma de México, Cuernavaca, Morelos 62210, México
| | - Heladia Salgado
- Programa de Genómica Computacional, Centro de Ciencias Genómicas, Universidad Nacional Autónoma de México, Cuernavaca, Morelos 62210, México
| | - Víctor H Bustamante
- Departamento de Microbiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Morelos 62210, México
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91
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The Type III Secretion System Effector SeoC of Salmonella enterica subsp. salamae and S. enterica subsp. arizonae ADP-Ribosylates Src and Inhibits Opsonophagocytosis. Infect Immun 2016; 84:3618-3628. [PMID: 27736780 PMCID: PMC5116738 DOI: 10.1128/iai.00704-16] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2016] [Accepted: 10/02/2016] [Indexed: 01/23/2023] Open
Abstract
Salmonella species utilize type III secretion systems (T3SSs) to translocate effectors into the cytosol of mammalian host cells, subverting cell signaling and facilitating the onset of gastroenteritis. In this study, we compared a draft genome assembly of Salmonella enterica subsp. salamae strain 3588/07 against the genomes of S. enterica subsp. enterica serovar Typhimurium strain LT2 and Salmonella bongori strain 12419. S. enterica subsp. salamae encodes the Salmonella pathogenicity island 1 (SPI-1), SPI-2, and the locus of enterocyte effacement (LEE) T3SSs. Though several key S Typhimurium effector genes are missing (e.g., avrA, sopB, and sseL), S. enterica subsp. salamae invades HeLa cells and contains homologues of S. bongori sboK and sboC, which we named seoC SboC and SeoC are homologues of EspJ from enteropathogenic and enterohemorrhagic Escherichia coli (EPEC and EHEC, respectively), which inhibit Src kinase-dependent phagocytosis by ADP-ribosylation. By screening 73 clinical and environmental Salmonella isolates, we identified EspJ homologues in S. bongori, S. enterica subsp. salamae, and Salmonella enterica subsp. arizonae The β-lactamase TEM-1 reporter system showed that SeoC is translocated by the SPI-1 T3SS. All the Salmonella SeoC/SboC homologues ADP-ribosylate Src E310 in vitro Ectopic expression of SeoC/SboC inhibited phagocytosis of IgG-opsonized beads into Cos-7 cells stably expressing green fluorescent protein (GFP)-FcγRIIa. Concurrently, S. enterica subsp. salamae infection of J774.A1 macrophages inhibited phagocytosis of beads, in a seoC-dependent manner. These results show that S. bongori, S. enterica subsp. salamae, and S. enterica subsp. arizonae share features of the infection strategy of extracellular pathogens EPEC and EHEC and shed light on the complexities of the T3SS effector repertoires of Enterobacteriaceae.
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92
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Choi J, Groisman EA. Acidic pH sensing in the bacterial cytoplasm is required for Salmonella virulence. Mol Microbiol 2016; 101:1024-38. [PMID: 27282333 PMCID: PMC5015592 DOI: 10.1111/mmi.13439] [Citation(s) in RCA: 84] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/08/2016] [Indexed: 01/12/2023]
Abstract
pH regulates gene expression, biochemical activities and cellular behaviors. A mildly acidic pH activates the master virulence regulatory system PhoP/PhoQ in the facultative intracellular pathogen Salmonella enterica serovar Typhimurium. The sensor PhoQ harbors an extracytoplasmic domain implicated in signal sensing, and a cytoplasmic domain controlling activation of the regulator PhoP. We now report that, surprisingly, a decrease in Salmonella's own cytoplasmic pH induces transcription of PhoP-activated genes even when the extracytoplasmic pH remains neutral. Amino acid substitutions in PhoQ's cytoplasmic domain hindered activation by acidic pH and attenuated virulence in mice, but did not abolish activation by low Mg(2+) or the antimicrobial peptide C18G. Conversely, removal of PhoQ's extracytoplasmic domains prevented the response to the latter PhoQ-activating signals but not to acidic pH. PhoP-dependent genes were minimally induced by acidic pH in the non-pathogenic species Salmonella bongori but were activated by low Mg(2+) and C18G as in pathogenic S. enterica. Our findings indicate that the sensor PhoQ enables S. enterica to respond to both host- and bacterial-derived signals that alter its cytoplasmic pH.
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Affiliation(s)
- Jeongjoon Choi
- Department of Microbial Pathogenesis, Yale School of Medicine, New Haven, CT, 06536, USA
| | - Eduardo A Groisman
- Department of Microbial Pathogenesis, Yale School of Medicine, New Haven, CT, 06536, USA.
- Yale Microbial Sciences Institute, West Haven, CT, 06516, USA.
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93
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McNally A, Thomson NR, Reuter S, Wren BW. 'Add, stir and reduce': Yersinia spp. as model bacteria for pathogen evolution. Nat Rev Microbiol 2016; 14:177-90. [PMID: 26876035 DOI: 10.1038/nrmicro.2015.29] [Citation(s) in RCA: 96] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Pathogenic species in the Yersinia genus have historically been targets for research aimed at understanding how bacteria evolve into mammalian pathogens. The advent of large-scale population genomic studies has greatly accelerated the progress in this field, and Yersinia pestis, Yersinia pseudotuberculosis and Yersinia enterocolitica have once again acted as model organisms to help shape our understanding of the evolutionary processes involved in pathogenesis. In this Review, we highlight the gene gain, gene loss and genome rearrangement events that have been identified by genomic studies in pathogenic Yersinia species, and we discuss how these findings are changing our understanding of pathogen evolution. Finally, as these traits are also found in the genomes of other species in the Enterobacteriaceae, we suggest that they provide a blueprint for the evolution of enteropathogenic bacteria.
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Affiliation(s)
- Alan McNally
- Pathogen Research Group, Nottingham Trent University, Clifton Lane, Nottingham NG11 8NS, UK
| | - Nicholas R Thomson
- Pathogen Genomics, Wellcome Trust Sanger Institute, Hinxton, Cambridge CB10 1SA, UK
| | - Sandra Reuter
- Department of Medicine, University of Cambridge, Box 157 Addenbrooke's Hospital, Hills Road, Cambridge CB2 2QQ, UK
| | - Brendan W Wren
- Department of Pathogen Molecular Biology, London School of Hygiene and Tropical Medicine, Keppel Street, London WC1E 7HT, UK
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94
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Elder JR, Chiok KL, Paul NC, Haldorson G, Guard J, Shah DH. The Salmonella pathogenicity island 13 contributes to pathogenesis in streptomycin pre-treated mice but not in day-old chickens. Gut Pathog 2016; 8:16. [PMID: 27141235 PMCID: PMC4852409 DOI: 10.1186/s13099-016-0098-0] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/29/2016] [Accepted: 04/03/2016] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Salmonella enterica serovar Enteritidis (S. Enteritidis) is a human and animal pathogen that causes gastroenteritis characterized by inflammatory diarrhea and occasionally an invasive systemic infection. Salmonella pathogenicity islands (SPIs) are horizontally acquired genomic segments known to contribute to Salmonella pathogenesis. The objective of the current study was to determine the contribution of SPI-13 to S. Enteritidis pathogenesis. METHODS We deleted the entire SPI-13 (∆SPI-13) from the genome of S. Enteritidis CDC_2010K_0968 strain isolated from a human patient during the 2010 egg-associated outbreak in the US. The kinetics of infection of the wild-type parent and the ∆SPI-13 were compared in orally challenged day-old chickens and streptomycin pre-treated mice. The degree of intestinal inflammation and the survival of mutant strain within the avian (HD11) and murine (RAW264.7) macrophages were also determined. RESULTS The deletion of the SPI-13 resulted in impaired infection kinetics of S. Enteritidis in streptomycin pre-treated mice which was characterized by significantly lower (P < 0.05) viable counts in the ceca, liver and spleen, impaired ability to induce intestinal inflammation and reduced survival within murine macrophages. Conversely, there were no significant differences in the infection kinetics of ∆SPI-13 in day-old chickens in any of the organs tested and the survival of ∆SPI-13 within chicken macrophages remained unaltered. CONCLUSIONS The results of this study show that SPI-13 contributes to the pathogenesis of S. Enteritidis in streptomycin pre-treated mice but not in day-old chickens and raises the possibility that SPI-13 may play a role in pathogenesis and the host adaptation/restriction of Salmonella serovars.
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Affiliation(s)
- Jacob R Elder
- Department of Veterinary Microbiology and Pathology, Washington State University, Pullman, WA 99164-7040 USA
| | - Kim Lam Chiok
- Department of Veterinary Microbiology and Pathology, Washington State University, Pullman, WA 99164-7040 USA
| | - Narayan C Paul
- Department of Veterinary Microbiology and Pathology, Washington State University, Pullman, WA 99164-7040 USA
| | - Gary Haldorson
- Department of Veterinary Microbiology and Pathology, Washington State University, Pullman, WA 99164-7040 USA
| | - Jean Guard
- Egg Quality and Safety Research Unit, Agriculture Research Service, United States Department of Agriculture, Athens, GA 30605 USA
| | - Devendra H Shah
- Department of Veterinary Microbiology and Pathology, Washington State University, Pullman, WA 99164-7040 USA ; Paul Allen School for Global Animal Health, College of Veterinary Medicine, Washington State University, Pullman, WA 99164-7040 USA
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95
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Selection of polyvalent bacteriophages infecting Salmonella enterica serovar Choleraesuis. ELECTRON J BIOTECHN 2016. [DOI: 10.1016/j.ejbt.2016.01.008] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
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96
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Abstract
The type VI secretion system (T6SS) is a multiprotein complex widespread in Proteobacteria and dedicated to the delivery of toxins into both prokaryotic and eukaryotic cells. It thus participates in interbacterial competition as well as pathogenesis. The T6SS is a contractile weapon, related to the injection apparatus of contractile tailed bacteriophages. Basically, it assembles an inner tube wrapped by a sheath-like structure and anchored to the cell envelope via a membrane complex. The energy released by the contraction of the sheath propels the inner tube through the membrane channel and toward the target cell. Although the assembly and the mechanism of action are conserved across species, the repertoire of secreted toxins and the diversity of the regulatory mechanisms and of target cells make the T6SS a highly versatile secretion system. The T6SS is particularly represented in Escherichia coli pathotypes and Salmonella serotypes. In this review we summarize the current knowledge regarding the prevalence, the assembly, the regulation, and the roles of the T6SS in E. coli, Salmonella, and related species.
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Affiliation(s)
- Laure Journet
- Laboratoire d'Ingénierie des Systèmes Macromoléculaires (LISM), Institut de Microbiologie de la Méditerranée (IMM), Centre National de la Recherche Scientifique (CNRS) - Aix-Marseille Université, UMR 7255, 13402 Marseille Cedex 20, France
| | - Eric Cascales
- Laboratoire d'Ingénierie des Systèmes Macromoléculaires (LISM), Institut de Microbiologie de la Méditerranée (IMM), Centre National de la Recherche Scientifique (CNRS) - Aix-Marseille Université, UMR 7255, 13402 Marseille Cedex 20, France
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97
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Robinson KS, Aw R. The Commonalities in Bacterial Effector Inhibition of Apoptosis. Trends Microbiol 2016; 24:665-680. [PMID: 27117049 DOI: 10.1016/j.tim.2016.04.002] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2016] [Revised: 03/13/2016] [Accepted: 04/01/2016] [Indexed: 02/09/2023]
Abstract
Antiapoptotic pathways of the host cell play integral roles in bacterial pathogenesis, with inhibition of those pathways resulting in halted disease pathology. Certain pathogens have developed elegant mechanisms to modulate the fate of the host cell, many of which target novel pathways that are poorly understood in the context of the cell biology. Bacterial pathogenesis research not only promotes the understanding of the role of antiapoptotic pathways in bacterial infection, but has a broader context in understanding the epitome of human disease, that is, developing the understanding of tumorigenic or inflammatory pathways. Here we review host antiapoptotic signalling pathways manipulated by translocated bacterial effectors that propagate the disease state, drawing common parallels and showing the novel differences.
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Affiliation(s)
- Keith S Robinson
- Department of Life Science, Imperial College London, London, UK.
| | - Rochelle Aw
- Department of Life Science, Imperial College London, London, UK
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98
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Ashton PM, Nair S, Peters TM, Bale JA, Powell DG, Painset A, Tewolde R, Schaefer U, Jenkins C, Dallman TJ, de Pinna EM, Grant KA. Identification of Salmonella for public health surveillance using whole genome sequencing. PeerJ 2016; 4:e1752. [PMID: 27069781 PMCID: PMC4824889 DOI: 10.7717/peerj.1752] [Citation(s) in RCA: 166] [Impact Index Per Article: 18.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2015] [Accepted: 02/12/2016] [Indexed: 01/01/2023] Open
Abstract
In April 2015, Public Health England implemented whole genome sequencing (WGS) as a routine typing tool for public health surveillance of Salmonella, adopting a multilocus sequence typing (MLST) approach as a replacement for traditional serotyping. The WGS derived sequence type (ST) was compared to the phenotypic serotype for 6,887 isolates of S. enterica subspecies I, and of these, 6,616 (96%) were concordant. Of the 4% (n = 271) of isolates of subspecies I exhibiting a mismatch, 119 were due to a process error in the laboratory, 26 were likely caused by the serotype designation in the MLST database being incorrect and 126 occurred when two different serovars belonged to the same ST. The population structure of S. enterica subspecies II–IV differs markedly from that of subspecies I and, based on current data, defining the serovar from the clonal complex may be less appropriate for the classification of this group. Novel sequence types that were not present in the MLST database were identified in 8.6% of the total number of samples tested (including S. enterica subspecies I–IV and S. bongori) and these 654 isolates belonged to 326 novel STs. For S. enterica subspecies I, WGS MLST derived serotyping is a high throughput, accurate, robust, reliable typing method, well suited to routine public health surveillance. The combined output of ST and serovar supports the maintenance of traditional serovar nomenclature while providing additional insight on the true phylogenetic relationship between isolates.
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Affiliation(s)
- Philip M Ashton
- Gastrointestinal Bacterial Reference Unit, Public Health England , London , United Kingdom
| | - Satheesh Nair
- Gastrointestinal Bacterial Reference Unit, Public Health England , London , United Kingdom
| | - Tansy M Peters
- Gastrointestinal Bacterial Reference Unit, Public Health England , London , United Kingdom
| | - Janet A Bale
- Gastrointestinal Bacterial Reference Unit, Public Health England , London , United Kingdom
| | - David G Powell
- Gastrointestinal Bacterial Reference Unit, Public Health England , London , United Kingdom
| | - Anaïs Painset
- Gastrointestinal Bacterial Reference Unit, Public Health England , London , United Kingdom
| | - Rediat Tewolde
- Applied Laboratory and Bio-Informatics Unit, Public Health England , London , United Kingdom
| | - Ulf Schaefer
- Applied Laboratory and Bio-Informatics Unit, Public Health England , London , United Kingdom
| | - Claire Jenkins
- Gastrointestinal Bacterial Reference Unit, Public Health England , London , United Kingdom
| | - Timothy J Dallman
- Gastrointestinal Bacterial Reference Unit, Public Health England , London , United Kingdom
| | - Elizabeth M de Pinna
- Gastrointestinal Bacterial Reference Unit, Public Health England , London , United Kingdom
| | - Kathie A Grant
- Gastrointestinal Bacterial Reference Unit, Public Health England, London, United Kingdom; Gastrointestinal Infections, NIHR Health Protection Research Unit in Gastrointestinal Infections, London, United Kingdom
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99
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Dehkordi MS, Doosti A, Arshi A. Deletion of Salmonella enterica serovar typhimurium sipC gene. Asian Pac J Trop Biomed 2015. [DOI: 10.1016/j.apjtb.2015.09.003] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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100
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Leonard SR, Lacher DW, Lampel KA. Acquisition of the lac operon by Salmonella enterica. BMC Microbiol 2015; 15:173. [PMID: 26303940 PMCID: PMC4549013 DOI: 10.1186/s12866-015-0511-8] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2015] [Accepted: 08/17/2015] [Indexed: 12/05/2022] Open
Abstract
Background Classical bacteriological characteristics of Salmonella enterica indicate that the members of this species are unable to utilize lactose as a carbon source. However, lactose-fermenting (Lac+) strains of several Salmonella serovars have been isolated from different foodborne outbreaks as well as different geographical regions worldwide. In the present study, we sequenced the genomes of 13 Lac + S. enterica isolates and characterized the lac region, comparing it to the lac region in other enteric bacterial species. Results Genetic analysis of the lac operons in the S. enterica genomes revealed that they all contain intact lacI, lacZ, and lacY genes. However, lacA was truncated in all of the S. enterica subsp. enterica isolates, encoding a 56 amino acid peptide rather than the full length 220 amino acid LacA protein. Molecular analyses of the 13 isolates revealed that the lac operon resided on a plasmid in some strains and in others was integrated into the bacterial chromosome. In most cases, an insertion sequence flanked at least one end of the operon. Interestingly, the S. enterica Montevideo and S. enterica Senftenberg isolates were found to harbor a plasmid with a high degree of sequence similarity to a plasmid from Klebsiella pneumoniae strain NK29 that also harbors the lac operon. In addition, two S. enterica Tennessee isolates carried two copies of the lac operon. Phylogenetic analysis based on lacIZY gene sequences determines distinct clusters, and reveals a greater correlation between lacIZY sequence and flanking organization than with either bacterial species or genomic location. Conclusions Our results indicate that the lac region is highly mobile among Enterobacteriaceae and demonstrate that the Lac + S. enterica subsp. enterica serovars acquired the lac region through parallel events. The acquisition of the lac operon by several S. enterica serovars may be indicative of environmental adaptation by these bacteria. Electronic supplementary material The online version of this article (doi:10.1186/s12866-015-0511-8) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Susan R Leonard
- Division of Molecular Biology, Center for Food Safety and Applied Nutrition, U.S. Food and Drug Administration, Laurel, MD, USA.
| | - David W Lacher
- Division of Molecular Biology, Center for Food Safety and Applied Nutrition, U.S. Food and Drug Administration, Laurel, MD, USA.
| | - Keith A Lampel
- Division of Molecular Biology, Center for Food Safety and Applied Nutrition, U.S. Food and Drug Administration, Laurel, MD, USA.
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