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Zhang Y, Liang S, Zhang S, Bai Q, Dai L, Wang J, Yao H, Zhang W, Liu G. Streptococcal arginine deiminase system defences macrophage bactericidal effect mediated by XRE family protein XtrSs. Virulence 2024; 15:2306719. [PMID: 38251714 PMCID: PMC10841013 DOI: 10.1080/21505594.2024.2306719] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2023] [Accepted: 01/12/2024] [Indexed: 01/23/2024] Open
Abstract
The arginine deiminase system (ADS) has been identified in various bacteria and functions to supplement energy production and enhance biological adaptability. The current understanding of the regulatory mechanism of ADS and its effect on bacterial pathogenesis is still limited. Here, we found that the XRE family transcriptional regulator XtrSs negatively affected Streptococcus suis virulence and significantly repressed ADS transcription when the bacteria were incubated in blood. Electrophoretic mobility shift (EMSA) and lacZ fusion assays further showed that XtrSs directly bind to the promoter of ArgR, an acknowledged positive regulator of bacterial ADS, to repress ArgR transcription. Moreover, we provided compelling evidence that S. suis could utilize arginine via ADS to adapt to acid stress, while ΔxtrSs enhanced this acid resistance by upregulating the ADS operon. Moreover, whole ADS-knockout S. suis increased arginine and antimicrobial NO in the infected macrophage cells, decreased intracellular survival, and even caused significant attenuation of bacterial virulence in a mouse infection model, while ΔxtrSs consistently presented the opposite results. Our experiments identified a novel ADS regulatory mechanism in S. suis, whereby XtrSs regulated ADS to modulate NO content in macrophages, promoting S. suis intracellular survival. Meanwhile, our findings provide a new perspective on how Streptococci evade the host's innate immune system.
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Affiliation(s)
- Yumin Zhang
- Sanya Institute of Nanjing Agricultural University, Nanjing Agricultural University, Sanya, China
- College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, China
- OIE Reference Lab for Swine Streptococcosis, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, China
- Joint International Research Laboratory of Animal Health and Food Safety, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, China
- Key Laboratory of Animal Bacteriology, Ministry of Agriculture, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, China
| | - Song Liang
- Sanya Institute of Nanjing Agricultural University, Nanjing Agricultural University, Sanya, China
- College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, China
- OIE Reference Lab for Swine Streptococcosis, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, China
- Joint International Research Laboratory of Animal Health and Food Safety, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, China
- Key Laboratory of Animal Bacteriology, Ministry of Agriculture, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, China
| | - Shidan Zhang
- Sanya Institute of Nanjing Agricultural University, Nanjing Agricultural University, Sanya, China
- College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, China
- OIE Reference Lab for Swine Streptococcosis, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, China
- Joint International Research Laboratory of Animal Health and Food Safety, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, China
- Key Laboratory of Animal Bacteriology, Ministry of Agriculture, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, China
| | - Qiankun Bai
- Sanya Institute of Nanjing Agricultural University, Nanjing Agricultural University, Sanya, China
- College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, China
- OIE Reference Lab for Swine Streptococcosis, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, China
- Joint International Research Laboratory of Animal Health and Food Safety, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, China
- Key Laboratory of Animal Bacteriology, Ministry of Agriculture, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, China
| | - Lei Dai
- Hainan Animal Disease Prevention and Control Center, Haikou, China
| | - Jinxiu Wang
- Hainan Animal Disease Prevention and Control Center, Haikou, China
| | - Huochun Yao
- Sanya Institute of Nanjing Agricultural University, Nanjing Agricultural University, Sanya, China
- College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, China
- OIE Reference Lab for Swine Streptococcosis, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, China
- Joint International Research Laboratory of Animal Health and Food Safety, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, China
- Key Laboratory of Animal Bacteriology, Ministry of Agriculture, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, China
| | - Wei Zhang
- Sanya Institute of Nanjing Agricultural University, Nanjing Agricultural University, Sanya, China
- College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, China
- OIE Reference Lab for Swine Streptococcosis, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, China
- Joint International Research Laboratory of Animal Health and Food Safety, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, China
- Key Laboratory of Animal Bacteriology, Ministry of Agriculture, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, China
| | - Guangjin Liu
- Sanya Institute of Nanjing Agricultural University, Nanjing Agricultural University, Sanya, China
- College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, China
- OIE Reference Lab for Swine Streptococcosis, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, China
- Joint International Research Laboratory of Animal Health and Food Safety, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, China
- Key Laboratory of Animal Bacteriology, Ministry of Agriculture, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, China
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2
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Jiang C, Zhou P, Zhang X, Ma N, Hu Y, Zhang M, Ghonaim AH, Li H, Dong L, Zeng W, Li C, Lang Y, Sun Y, He Q, Li W. ARF6 promotes Streptococcus suis suilysin induced apoptosis in HBMECs. Int J Biol Macromol 2024; 268:131839. [PMID: 38663699 DOI: 10.1016/j.ijbiomac.2024.131839] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2024] [Revised: 04/21/2024] [Accepted: 04/22/2024] [Indexed: 05/02/2024]
Abstract
Streptococcus suis (S. suis) is a significant zoonotic microorganism that causes a severe illness in both pigs and humans and is characterized by severe meningitis and septicemia. Suilysin (SLY), which is secreted by S. suis, plays a crucial role as a virulence factor in the disease. To date, the interaction between SLY and host cells is not fully understood. In this study, we identified the interacting proteins between SLY and human brain microvascular endothelial cells (HBMECs) using the TurboID-mediated proximity labeling method. 251 unique proteins were identified in TurboID-SLY treated group, of which six plasma membrane proteins including ARF6, GRK6, EPB41L5, DSC1, TJP2, and PNN were identified. We found that the proteins capable of interacting with SLY are ARF6 and PNN. Subsequent investigations revealed that ARF6 substantially increased the invasive ability of S. suis in HBMECs. Furthermore, ARF6 promoted SLY-induced the activation of p38 MAPK signaling pathway in HBMECs. Moreover, ARF6 promoted the apoptosis in HBMECs through the activation of p38 MAPK signaling pathway induced by SLY. Finally, we confirmed that ARF6 could increase the virulence of SLY in C57BL/6 mice. These findings offer valuable insights that contribute to a deeper understanding of the pathogenic mechanism of SLY.
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Affiliation(s)
- Changsheng Jiang
- National Key Laboratory of Agricultural Microbiology, College of Animal Sciences and Veterinary Medicine, Huazhong Agricultural University, The Cooperative Innovation Center for Sustainable Pig Production, Wuhan 430070, China
| | - Pei Zhou
- National Key Laboratory of Agricultural Microbiology, College of Animal Sciences and Veterinary Medicine, Huazhong Agricultural University, The Cooperative Innovation Center for Sustainable Pig Production, Wuhan 430070, China
| | - Xiaoqian Zhang
- China Institute of Veterinary Drug Control, Beijing 102629, China
| | - NingNing Ma
- National Key Laboratory of Agricultural Microbiology, College of Animal Sciences and Veterinary Medicine, Huazhong Agricultural University, The Cooperative Innovation Center for Sustainable Pig Production, Wuhan 430070, China
| | - Yaofang Hu
- National Key Laboratory of Agricultural Microbiology, College of Animal Sciences and Veterinary Medicine, Huazhong Agricultural University, The Cooperative Innovation Center for Sustainable Pig Production, Wuhan 430070, China
| | - Mengjia Zhang
- National Key Laboratory of Agricultural Microbiology, College of Animal Sciences and Veterinary Medicine, Huazhong Agricultural University, The Cooperative Innovation Center for Sustainable Pig Production, Wuhan 430070, China
| | - Ahmed H Ghonaim
- National Key Laboratory of Agricultural Microbiology, College of Animal Sciences and Veterinary Medicine, Huazhong Agricultural University, The Cooperative Innovation Center for Sustainable Pig Production, Wuhan 430070, China; Desert Research Center, Cairo 11435, Egypt
| | - Huimin Li
- National Key Laboratory of Agricultural Microbiology, College of Animal Sciences and Veterinary Medicine, Huazhong Agricultural University, The Cooperative Innovation Center for Sustainable Pig Production, Wuhan 430070, China
| | - Ling Dong
- National Key Laboratory of Agricultural Microbiology, College of Animal Sciences and Veterinary Medicine, Huazhong Agricultural University, The Cooperative Innovation Center for Sustainable Pig Production, Wuhan 430070, China
| | - Wei Zeng
- Hubei Key Laboratory of Animal Embryo Engineering and Molecular Breeding, Hubei Academy of Agricultural Sciences, Wuhan 430064, China
| | - Chang Li
- Key Laboratory of Prevention and Control Agents for Animal Bacteriosis, Ministry of Agriculture and Rural Affairs, Institute of Animal Husbandry and Veterinary, Hubei Academy of Agricultural Sciences, Wuhan 430064, China
| | - Yifei Lang
- College of Veterinary Medicine, Sichuan Agricultural University, Chengdu 611130, China
| | - Yumei Sun
- National Key Laboratory of Agricultural Microbiology, College of Animal Sciences and Veterinary Medicine, Huazhong Agricultural University, The Cooperative Innovation Center for Sustainable Pig Production, Wuhan 430070, China
| | - Qigai He
- National Key Laboratory of Agricultural Microbiology, College of Animal Sciences and Veterinary Medicine, Huazhong Agricultural University, The Cooperative Innovation Center for Sustainable Pig Production, Wuhan 430070, China.
| | - Wentao Li
- National Key Laboratory of Agricultural Microbiology, College of Animal Sciences and Veterinary Medicine, Huazhong Agricultural University, The Cooperative Innovation Center for Sustainable Pig Production, Wuhan 430070, China; Hubei Hongshan Laboratory, Wuhan 430070, China.
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3
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Kobayashi K, Kubota H, Tohya M, Ushikubo M, Yamamoto M, Ariyoshi T, Uchitani Y, Mitobe M, Okuno R, Nakagawa I, Sekizaki T, Suzuki J, Sadamasu K. Characterization of pig tonsils as niches for the generation of Streptococcus suis diversity. Vet Res 2024; 55:17. [PMID: 38321502 PMCID: PMC10848530 DOI: 10.1186/s13567-024-01270-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2023] [Accepted: 01/12/2024] [Indexed: 02/08/2024] Open
Abstract
Streptococcus suis is a gram-positive bacterium that causes meningitis, septicemia, endocarditis, and other disorders in pigs and humans. We obtained 42 and 50 S. suis isolates from lesions of porcine endocarditis and palatine tonsils, respectively, of clinically healthy pigs in Japan; we then determined their sequence types (STs) by multilocus sequence typing (MLST), cps genotypes, serotypes, and presence of classical major virulence-associated marker genes (mrp, epf, and sly). The 42 isolates from endocarditis lesions were assigned to a limited number of STs and clonal complexes (CCs). On the other hand, the 50 isolates from tonsils were diverse in these traits and seemingly in the degree of virulence, suggesting that tonsils can accommodate a variety of S. suis isolates. The goeBURST full algorithm using tonsil isolates obtained in this study and those retrieved from the database showed that major CCs as well as many other clusters were composed of isolates originating from different countries, and some of the STs were very similar to each other despite the difference in country of origin. These findings indicate that S. suis with not only different but also similar mutations in the genome have survived in tonsils independently across different geographical locations. Therefore, unlike the lesions of endocarditis, the tonsils of pigs seemingly accommodate various S. suis lineages. The present study suggests that S. suis acquired its diversity by natural mutations during colonization and persistence in the tonsils of pigs.
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Affiliation(s)
- Kai Kobayashi
- Department of Microbiology, Tokyo Metropolitan Institute of Public Health, Hyakunincho 3-24-1, Shinjuku-ku, Tokyo, 169-0073, Japan.
| | - Hiroaki Kubota
- Department of Microbiology, Tokyo Metropolitan Institute of Public Health, Hyakunincho 3-24-1, Shinjuku-ku, Tokyo, 169-0073, Japan
| | - Mari Tohya
- Division of Biomedical Food Research, National Institute of Health Sciences, Tonomachi 3-25-26, Kawasaki-ku, Kawasaki-shi, Kanagawa, 210-9501, Japan
- Department of Microbiology and Department of Microbiome Research, Juntendo University School of Medicine, Hongo 2-1-1, Bunkyo-ku, Tokyo, 113-8421, Japan
| | - Megumi Ushikubo
- Shibaura Meat Sanitary Inspection Station, Tokyo Metropolitan Government, Konan 2-7-19, Minato-ku, Tokyo, 108-0075, Japan
| | - Miki Yamamoto
- Shibaura Meat Sanitary Inspection Station, Tokyo Metropolitan Government, Konan 2-7-19, Minato-ku, Tokyo, 108-0075, Japan
| | - Tsukasa Ariyoshi
- Department of Microbiology, Tokyo Metropolitan Institute of Public Health, Hyakunincho 3-24-1, Shinjuku-ku, Tokyo, 169-0073, Japan
| | - Yumi Uchitani
- Department of Microbiology, Tokyo Metropolitan Institute of Public Health, Hyakunincho 3-24-1, Shinjuku-ku, Tokyo, 169-0073, Japan
| | - Morika Mitobe
- Department of Microbiology, Tokyo Metropolitan Institute of Public Health, Hyakunincho 3-24-1, Shinjuku-ku, Tokyo, 169-0073, Japan
| | - Rumi Okuno
- Department of Microbiology, Tokyo Metropolitan Institute of Public Health, Hyakunincho 3-24-1, Shinjuku-ku, Tokyo, 169-0073, Japan
| | - Ichiro Nakagawa
- Department of Microbiology, Graduate School of Medicine, Kyoto University, Yoshida-Konoe-cho, Sakyo-ku, Kyoto, 606-8501, Japan
| | - Tsutomu Sekizaki
- Department of Microbiology, Graduate School of Medicine, Kyoto University, Yoshida-Konoe-cho, Sakyo-ku, Kyoto, 606-8501, Japan
- Research Center for Food Safety, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Yayoi 1-1-1, Bunkyo-ku, Tokyo, 113-8657, Japan
| | - Jun Suzuki
- Department of Microbiology, Tokyo Metropolitan Institute of Public Health, Hyakunincho 3-24-1, Shinjuku-ku, Tokyo, 169-0073, Japan
| | - Kenji Sadamasu
- Department of Microbiology, Tokyo Metropolitan Institute of Public Health, Hyakunincho 3-24-1, Shinjuku-ku, Tokyo, 169-0073, Japan
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4
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Guo G, Zhang Y, Wei D, Wang Z, Li Q, Yu Y, Zhang W. Contribution of nadR to the cell growth and virulence of Streptococcus suis serotype 2. Vet Microbiol 2024; 288:109928. [PMID: 38056180 DOI: 10.1016/j.vetmic.2023.109928] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2022] [Revised: 10/06/2023] [Accepted: 11/20/2023] [Indexed: 12/08/2023]
Abstract
Streptococcus suis serotype 2 (SS2) has been reported to be a highly invasive pathogen in swine and a zoonotic agent for humans. Although many bacterial virulence factors have been identified, our an insightful understanding of SS2 pathogenicity is lacking. The gene nadR, encoding nicotinamide-nucleotide adenylyltransferase, was first reported as a regulator and transporter of the intracellular NAD synthesis pathway in Salmonella typhimurium. In this study, we constructed a mutant strain of nadR (ΔnadR) to test the phenotypic and virulence variations between the deletion mutant and the wild-type strain ZY05719. The phenotypic experimental results showed that ΔnadR obviously inhibited cell growth and exhibited shorter chains than WT. The growth defect of ΔnadR was caused by the loss of the function of nadR for transporting the substrates nicotinamide mononucleotide and nicotinamide riboside in the intracellular NAD synthesis pathway. In the process of interaction with the host, ΔnadR participated in adherence and invasion to the host cells, and it was more easily cleared by RAW264.7 macrophages. More importantly, both zebrafish and BALB/c mice in vivo virulence experimental results showed that ΔnadR dramatically attenuated the virulence of SS2, and the ability of ΔnadR to colonize tissues was notably reduced in comparison with that of WT in the BALB/c mice infection model. To the best of our knowledge, this is the first time to demonstrate that nadR not only plays an important role in bacterial growth, but also in connection with the virulence of SS2 as a global transcriptional regulator.
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Affiliation(s)
- Genglin Guo
- Shandong Institute of Sericulture, Shandong Academy of Agricultural Sciences, Yantai, China
| | - Yuhang Zhang
- College of Veterinary Medicine, Nanjing Agricultural University, Nanjing 210095, China; OIE Reference Lab for Swine Streptococcosis, Nanjing 210095, China; MOE Joint International Research Laboratory of Animal Health and Food Safety, Nanjing, China; The Sanya Institute of Nanjing Agricultural University, Sanya, China
| | - Dan Wei
- College of Veterinary Medicine, Nanjing Agricultural University, Nanjing 210095, China; OIE Reference Lab for Swine Streptococcosis, Nanjing 210095, China; MOE Joint International Research Laboratory of Animal Health and Food Safety, Nanjing, China; The Sanya Institute of Nanjing Agricultural University, Sanya, China
| | - Zhuohao Wang
- College of Veterinary Medicine, Nanjing Agricultural University, Nanjing 210095, China; OIE Reference Lab for Swine Streptococcosis, Nanjing 210095, China; MOE Joint International Research Laboratory of Animal Health and Food Safety, Nanjing, China; The Sanya Institute of Nanjing Agricultural University, Sanya, China
| | - Quan Li
- College of Veterinary Medicine, Yangzhou University, Yangzhou, China
| | - Yanfei Yu
- College of Veterinary Medicine, Nanjing Agricultural University, Nanjing 210095, China; Institute of Veterinary Medicine, Jiangsu Academy of Agricultural Sciences, Key Laboratory of Veterinary Biological Engineering and Technology, Ministry of Agriculture and Rural Affairs, Nanjing, China; School of Food and Biological Engineering, Jiangsu University, Zhenjiang, China
| | - Wei Zhang
- College of Veterinary Medicine, Nanjing Agricultural University, Nanjing 210095, China; OIE Reference Lab for Swine Streptococcosis, Nanjing 210095, China; MOE Joint International Research Laboratory of Animal Health and Food Safety, Nanjing, China; The Sanya Institute of Nanjing Agricultural University, Sanya, China.
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5
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Gussak A, Ferrando ML, Schrama M, van Baarlen P, Wells JM. Precision Genome Engineering in Streptococcus suis Based on a Broad-Host-Range Vector and CRISPR-Cas9 Technology. ACS Synth Biol 2023; 12:2546-2560. [PMID: 37602730 PMCID: PMC10510748 DOI: 10.1021/acssynbio.3c00110] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2023] [Indexed: 08/22/2023]
Abstract
Streptococcussuis is an important zoonotic pathogen that causes severe invasive disease in pigs and humans. Current methods for genome engineering of S. suis rely on the insertion of antibiotic resistance markers, which is time-consuming and labor-intensive and does not allow the precise introduction of small genomic mutations. Here we developed a system for CRISPR-based genome editing in S. suis, utilizing linear DNA fragments for homologous recombination (HR) and a plasmid-based negative selection system for bacteria not edited by HR. To enable the use of this system in other bacteria, we engineered a broad-host-range replicon in the CRISPR plasmid. We demonstrated the utility of this system to rapidly introduce multiple gene deletions in successive rounds of genome editing and to make precise nucleotide changes in essential genes. Furthermore, we characterized a mechanism by which S. suis can escape killing by a targeted Cas9-sgRNA complex in the absence of HR. A characteristic of this new mechanism is the presence of very slow-growing colonies in a persister-like state that may allow for DNA repair or the introduction of mutations, alleviating Cas9 pressure. This does not impact the utility of CRISPR-based genome editing because the escape colonies are easily distinguished from genetically edited clones due to their small colony size. Our CRISPR-based editing system is a valuable addition to the genetic toolbox for engineering of S. suis, as it accelerates the process of mutant construction and simplifies the removal of antibiotic markers between successive rounds of genome editing.
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Affiliation(s)
- Alex Gussak
- Host-Microbe Interactomics, Animal
Sciences, Wageningen University, 6708 WD Wageningen, The Netherlands
| | | | | | - Peter van Baarlen
- Host-Microbe Interactomics, Animal
Sciences, Wageningen University, 6708 WD Wageningen, The Netherlands
| | - Jerry Mark Wells
- Host-Microbe Interactomics, Animal
Sciences, Wageningen University, 6708 WD Wageningen, The Netherlands
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6
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Genome analysis provides insight into hyper-virulence of Streptococcus suis LSM178, a human strain with a novel sequence type 1005. Sci Rep 2021; 11:23919. [PMID: 34907269 PMCID: PMC8671398 DOI: 10.1038/s41598-021-03370-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2021] [Accepted: 11/30/2021] [Indexed: 11/16/2022] Open
Abstract
Streptococcus suis has been well-recognized as a zoonotic pathogen worldwide, and the diversity and unpredictable adaptive potential of sporadic human strains represent a great risk to the public health. In this study, S. suis LSM178, isolated from a patient in contact with pigs and raw pork, was assessed as a hyper-virulent strain and interpreted for the virulence based on its genetic information. The strain was more invasive for Caco-2 cells than two other S. suis strains, SC19 and P1/7. Sequence analysis designated LSM178 with serotype 2 and a novel sequence type 1005. Phylogenetic analysis showed that LSM178 clustered with highly virulent strains including all human strains and epidemic strains. Compared with other strains, these S. suis have the most and the same virulent factors and a type I-89 K pathogenicity island. Further, groups of genes were identified to distinguish these highly virulent strains from other generally virulent strains, emphasizing the key roles of genes modeling transcription, cell barrier, replication, recombination and repair on virulence regulation. Additionally, LSM178 contains a novel prophage conducive potentially to pathogenicity.
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7
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Roodsant TJ, Van Der Putten BCL, Tamminga SM, Schultsz C, Van Der Ark KCH. Identification of Streptococcus suis putative zoonotic virulence factors: A systematic review and genomic meta-analysis. Virulence 2021; 12:2787-2797. [PMID: 34666617 PMCID: PMC8632099 DOI: 10.1080/21505594.2021.1985760] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022] Open
Abstract
Streptococcus suis is an emerging zoonotic pathogen. Over 100 putative virulence factors have been described, but it is unclear to what extent these virulence factors could contribute to zoonotic potential of S. suis. We identified all S. suis virulence factors studied in experimental models of human origin in a systematic review and assessed their contribution to zoonotic potential in a subsequent genomic meta-analysis. PubMed and Scopus were searched for English-language articles that studied S. suis virulence published until 31 March 2021. Articles that analyzed a virulence factor by knockout mutation, purified protein, and/or recombinant protein in a model of human origin, were included. Data on virulence factor, strain characteristics, used human models and experimental outcomes were extracted. All publicly available S. suis genomes with available metadata on host, disease status and country of origin, were included in a genomic meta-analysis. We calculated the ratio of the prevalence of each virulence factor in human and pig isolates. We included 130 articles and 1703 S. suis genomes in the analysis. We identified 53 putative virulence factors that were encoded by genes which are part of the S. suis core genome and 26 factors that were at least twice as prevalent in human isolates as in pig isolates. Hhly3 and NisK/R were particularly enriched in human isolates, after stratification by genetic lineage and country of isolation. This systematic review and genomic meta-analysis have identified virulence factors that are likely to contribute to the zoonotic potential of S. suis.
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Affiliation(s)
- Thomas J Roodsant
- Amsterdam UMC, University of Amsterdam, Department of Global Health-Amsterdam, Institute for Global Health and Development, Amsterdam, Netherlands.,Department of Medical Microbiology, Amsterdam UMC, University of Amsterdam, Amsterdam, Netherlands
| | - Boas C L Van Der Putten
- Amsterdam UMC, University of Amsterdam, Department of Global Health-Amsterdam, Institute for Global Health and Development, Amsterdam, Netherlands.,Department of Medical Microbiology, Amsterdam UMC, University of Amsterdam, Amsterdam, Netherlands
| | - Sara M Tamminga
- Department of Medical Microbiology, Amsterdam UMC, University of Amsterdam, Amsterdam, Netherlands
| | - Constance Schultsz
- Amsterdam UMC, University of Amsterdam, Department of Global Health-Amsterdam, Institute for Global Health and Development, Amsterdam, Netherlands.,Department of Medical Microbiology, Amsterdam UMC, University of Amsterdam, Amsterdam, Netherlands
| | - Kees C H Van Der Ark
- Amsterdam UMC, University of Amsterdam, Department of Global Health-Amsterdam, Institute for Global Health and Development, Amsterdam, Netherlands.,Department of Medical Microbiology, Amsterdam UMC, University of Amsterdam, Amsterdam, Netherlands
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8
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Lu Y, Li S, Shen X, Zhao Y, Zhou D, Hu D, Cai X, Lu L, Xiong X, Li M, Cao M. The type II histidine triad protein HtpsC facilitates invasion of epithelial cells by highly virulent Streptococcus suis serotype 2. J Microbiol 2021; 59:949-957. [PMID: 34491523 DOI: 10.1007/s12275-021-1129-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2021] [Revised: 07/19/2021] [Accepted: 07/20/2021] [Indexed: 10/20/2022]
Abstract
Streptococcus suis serotype 2 (S. suis 2) is an important zoonotic pathogen that presents a significant threat both to pigs and to workers in the pork industry. The initial steps of S. suis 2 pathogenesis are unclear. In this study, we found that the type II histidine triad protein HtpsC from the highly virulent Chinese isolate 05ZYH33 is structurally similar to internalin A (InlA) from Listeria monocytogenes, which plays an important role in mediating listerial invasion of epithelial cells. To determine if HtpsC and InlA function similarly, an isogenic htpsC mutant (ΔhtpsC) was generated in S. suis by homologous recombination. The htpsC deletion strain exhibited a diminished ability to adhere to and invade epithelial cells from different sources. Double immunofluorescence microscopy also revealed reduced survival of the ΔhtpsC mutant after co-cultivation with epithelium. Adhesion to epithelium and invasion by the wild type strain was inhibited by a monoclonal antibody against E-cadherin. In contrast, the htpsC-deficient mutant was unaffected by the same treatment, suggesting that E-cadherin is the host-cell receptor that interacts with HtpsC and facilitates bacterial internalization. Based on these results, we propose that HtpsC is involved in the process by which S. suis 2 penetrates host epithelial cells, and that this protein is an important virulence factor associated with cell adhesion and invasion.
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Affiliation(s)
- Yunjun Lu
- College Food Science and Light Industry, Nanjing Tech University, Nanjing, 211816, Jiangsu, P. R. China
| | - Shu Li
- Department of Microbiology, College of Basic Medical Sciences, Army Medical University (Third Military Medical University), Key Laboratory of Microbial Engineering under the Educational Committee in Chongqing, Chongqing, 400038, P. R. China
| | - Xiaodong Shen
- Department of Microbiology, College of Basic Medical Sciences, Army Medical University (Third Military Medical University), Key Laboratory of Microbial Engineering under the Educational Committee in Chongqing, Chongqing, 400038, P. R. China
| | - Yan Zhao
- Department of Microbiology, College of Basic Medical Sciences, Army Medical University (Third Military Medical University), Key Laboratory of Microbial Engineering under the Educational Committee in Chongqing, Chongqing, 400038, P. R. China
| | - Dongming Zhou
- Center for Disease Control and Prevention for the Eastern Theater Command, Nanjing, 210002, Jiangsu, P. R. China
| | - Dan Hu
- Center for Disease Control and Prevention for the Eastern Theater Command, Nanjing, 210002, Jiangsu, P. R. China
| | - Xushen Cai
- College Food Science and Light Industry, Nanjing Tech University, Nanjing, 211816, Jiangsu, P. R. China
| | - Lixia Lu
- College Food Science and Light Industry, Nanjing Tech University, Nanjing, 211816, Jiangsu, P. R. China
| | - Xiaohui Xiong
- College Food Science and Light Industry, Nanjing Tech University, Nanjing, 211816, Jiangsu, P. R. China
| | - Ming Li
- Department of Microbiology, College of Basic Medical Sciences, Army Medical University (Third Military Medical University), Key Laboratory of Microbial Engineering under the Educational Committee in Chongqing, Chongqing, 400038, P. R. China.
| | - Min Cao
- College Food Science and Light Industry, Nanjing Tech University, Nanjing, 211816, Jiangsu, P. R. China.
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9
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Gu Q, He P, Wang D, Ma J, Zhong X, Zhu Y, Zhang Y, Bai Q, Pan Z, Yao H. An Auto-Regulating Type II Toxin-Antitoxin System Modulates Drug Resistance and Virulence in Streptococcus suis. Front Microbiol 2021; 12:671706. [PMID: 34475853 PMCID: PMC8406773 DOI: 10.3389/fmicb.2021.671706] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2021] [Accepted: 05/26/2021] [Indexed: 11/13/2022] Open
Abstract
Toxin-antitoxin (TA) systems are ubiquitous genetic elements that play an essential role in multidrug tolerance and virulence of bacteria. So far, little is known about the TA systems in Streptococcus suis. In this study, the Xress-MNTss TA system, composed of the MNTss toxin in the periplasmic space and its interacting Xress antitoxin, was identified in S. suis. β-galactosidase activity and electrophoretic mobility shift assay (EMSA) revealed that Xress and the Xress-MNTss complex could bind directly to the Xress-MNTss promoter as well as downregulate streptomycin adenylyltransferase ZY05719_RS04610. Interestingly, the Xress deletion mutant was less pathogenic in vivo following a challenge in mice. Transmission electron microscopy and adhesion assays pointed to a significantly thinner capsule but greater biofilm-formation capacity in ΔXress than in the wild-type strain. These results indicate that Xress-MNTss, a new type II TA system, plays an important role in antibiotic resistance and pathogenicity in S. suis.
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Affiliation(s)
- Qibing Gu
- College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, China.,Key Laboratory of Animal Bacteriology, Ministry of Agriculture, Nanjing, China.,OIE Reference Laboratory for Swine Streptococcosis, Nanjing, China
| | - Peijuan He
- College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, China.,Key Laboratory of Animal Bacteriology, Ministry of Agriculture, Nanjing, China.,OIE Reference Laboratory for Swine Streptococcosis, Nanjing, China
| | - Dan Wang
- College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, China.,Key Laboratory of Animal Bacteriology, Ministry of Agriculture, Nanjing, China.,OIE Reference Laboratory for Swine Streptococcosis, Nanjing, China
| | - Jiale Ma
- College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, China.,Key Laboratory of Animal Bacteriology, Ministry of Agriculture, Nanjing, China.,OIE Reference Laboratory for Swine Streptococcosis, Nanjing, China
| | - Xiaojun Zhong
- College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, China.,Key Laboratory of Animal Bacteriology, Ministry of Agriculture, Nanjing, China.,OIE Reference Laboratory for Swine Streptococcosis, Nanjing, China.,College of Animal Science and Technology, College of Veterinary Medicine, Zhejiang A&F University, Hangzhou, China
| | - Yinchu Zhu
- College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, China.,Key Laboratory of Animal Bacteriology, Ministry of Agriculture, Nanjing, China.,OIE Reference Laboratory for Swine Streptococcosis, Nanjing, China.,Institute of Animal Husbandry and Veterinary Sciences, Zhejiang Academy of Agricultural Sciences, Hangzhou, China
| | - Yue Zhang
- College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, China.,Key Laboratory of Animal Bacteriology, Ministry of Agriculture, Nanjing, China.,OIE Reference Laboratory for Swine Streptococcosis, Nanjing, China.,College of Veterinary Medicine, Henan Agricultural University, Zhengzhou, China
| | - Qiankun Bai
- College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, China.,Key Laboratory of Animal Bacteriology, Ministry of Agriculture, Nanjing, China.,OIE Reference Laboratory for Swine Streptococcosis, Nanjing, China
| | - Zihao Pan
- College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, China.,Key Laboratory of Animal Bacteriology, Ministry of Agriculture, Nanjing, China.,OIE Reference Laboratory for Swine Streptococcosis, Nanjing, China
| | - Huochun Yao
- College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, China.,Key Laboratory of Animal Bacteriology, Ministry of Agriculture, Nanjing, China.,OIE Reference Laboratory for Swine Streptococcosis, Nanjing, China
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10
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Tohya M, Dozaki S, Ishida-Kuroki K, Watanabe T, Sekizaki T. Basis of the persistence of capsule-negative Streptococcus suis in porcine endocarditis inferred from comparative genomics. FEMS Microbiol Lett 2021; 368:6315327. [PMID: 34223887 DOI: 10.1093/femsle/fnab083] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2021] [Accepted: 07/01/2021] [Indexed: 11/14/2022] Open
Abstract
The capsule (cap) of Streptococcus suis is an anti-phagocytic element and is one of the major virulence factors. However, we have found cap-positive and cap-negative isolates in porcine endocarditis. Here, we compared genome sequences of multiple cap-negative isolates with those of a cap-positive isolate from a single endocarditis. Cap-positive and cap-negative isolates from the same pig were phylogenetically closest compared with those from other pigs. Some of cap-negative isolates from the same pig showed different mutations in capsular polysaccharide synthesis (cps) genes, suggesting that these isolates arisen in pigs after infection. Different mutations in whole-genomes were also found among isolates with identical mutations in cps genes, indicating that mutations in cps genes and the whole-genome occurred independently. Since cap-negative isolates are rarely found in lesions of other diseases, these results suggest that endocarditis lesions may simply favored cap-negative mutants to survive the niches, leading to their persistence in the lesions.
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Affiliation(s)
- Mari Tohya
- Research Center for Food Safety, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Yayoi 1-1-1, Bunkyo-ku, Tokyo 113-8657, Japan.,Department of Microbiology, Juntendo University School of Medicine, Hongo 2-1-1, Bunkyo-ku, Tokyo 113-8421, Japan
| | - Shinichi Dozaki
- Research Center for Food Safety, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Yayoi 1-1-1, Bunkyo-ku, Tokyo 113-8657, Japan
| | - Kasumi Ishida-Kuroki
- Research Center for Food Safety, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Yayoi 1-1-1, Bunkyo-ku, Tokyo 113-8657, Japan.,Antimicrobial Resistance Research Center, National Institute of Infectious Diseases, Aoba-cho 4-2-1, Higashimurayama, Tokyo, 189-0002, Japan
| | - Takayasu Watanabe
- Research Center for Food Safety, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Yayoi 1-1-1, Bunkyo-ku, Tokyo 113-8657, Japan.,Department of Chemistry, Nihon University School of Dentistry, 1-8-13 Kanda-Surugadai, Chiyoda-ku, Tokyo 101-8310, Japan
| | - Tsutomu Sekizaki
- Research Center for Food Safety, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Yayoi 1-1-1, Bunkyo-ku, Tokyo 113-8657, Japan.,Department of Microbiology, Graduate School of Medicine, Kyoto University, Yoshida-Konoe-cho, Sakyo-ku, Kyoto, 606-8501, Japan
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11
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Vötsch D, Willenborg M, Baumgärtner W, Rohde M, Valentin-Weigand P. Bordetella bronchiseptica promotes adherence, colonization, and cytotoxicity of Streptococcus suis in a porcine precision-cut lung slice model. Virulence 2020; 12:84-95. [PMID: 33372837 PMCID: PMC7781633 DOI: 10.1080/21505594.2020.1858604] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/04/2022] Open
Abstract
Bordetella (B.) bronchiseptica and Streptococcus (S.) suis are major pathogens in pigs, which are frequently isolated from co-infections in the respiratory tract and contribute to the porcine respiratory disease complex (PRDC). Despite the high impact of co-infections on respiratory diseases of swine (and other hosts), very little is known about pathogen-pathogen-host interactions and the mechanisms of pathogenesis. In the present study, we established a porcine precision-cut lung slice (PCLS) model to analyze the effects of B. bronchiseptica infection on adherence, colonization, and cytotoxic effects of S. suis. We hypothesized that induction of ciliostasis by a clinical isolate of B. bronchiseptica may promote subsequent infection with a virulent S. suis serotype 2 strain. To investigate this theory, we monitored the ciliary activity by light microscopy, measured the release of lactate dehydrogenase, and calculated the number of PCLS-associated bacteria. To study the role of the pore-forming toxin suilysin (SLY) in S. suis-induced cytotoxicity, we included a SLY-negative isogenic mutant and the complemented mutant strain. Furthermore, we analyzed infected PCLS by histopathology, immunofluorescence microscopy, and field emission scanning electron microscopy. Our results showed that pre-infection with B. bronchiseptica promoted adherence, colonization, and, as a consequence of the increased colonization, the cytotoxic effects of S. suis, probably by reduction of the ciliary activity. Moreover, cytotoxicity induced by S. suis is strictly dependent on the presence of SLY. Though the underlying molecular mechanisms remain to be fully clarified, our results clearly support the hypothesis that B. bronchiseptica paves the way for S. suis infection.
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Affiliation(s)
- Désirée Vötsch
- Institute for Microbiology, University of Veterinary Medicine Hannover , Hannover, Germany
| | - Maren Willenborg
- Institute for Microbiology, University of Veterinary Medicine Hannover , Hannover, Germany
| | - Wolfgang Baumgärtner
- Institute for Pathology, University of Veterinary Medicine Hannover , Hannover, Germany
| | - Manfred Rohde
- Central Facility for Microscopy, Helmholtz Center for Infection Research , Braunschweig, Germany
| | - Peter Valentin-Weigand
- Institute for Microbiology, University of Veterinary Medicine Hannover , Hannover, Germany
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12
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Screening of Virulence-Related Transcriptional Regulators in Streptococcus suis. Genes (Basel) 2020; 11:genes11090972. [PMID: 32825733 PMCID: PMC7564649 DOI: 10.3390/genes11090972] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2020] [Revised: 08/12/2020] [Accepted: 08/13/2020] [Indexed: 01/08/2023] Open
Abstract
Streptococcus suis (S.suis) is an important zoonotic pathogen that causes many severe diseases in pigs and humans. Virulence-related transcriptional regulators have been widely reported in pathogenic microorganisms, but only a few have been identified in S.suis. Our aim was to screen virulence-related transcriptional regulators in S.suis. A total of 89 such genes were predicted in the S.suis genome, of which 22 were up-regulated and 18 were down-regulated during S.suis infection in mice. To evaluate the roles of these differentially expressed factors in S.suis virulence, deletion mutants were constructed, and 10 mutants were successfully obtained. Among these genes, the deletion of comR, sitR, or sxvR caused significantly decreased virulence in mice, compared to that with the wild-type strain. Moreover, the survival of ΔcomR, ΔsitR, and ΔsxvR mutant strains in blood was significantly reduced both in vitro and in vivo. Furthermore, their pro-inflammatory abilities were also obviously decreased in vivo. The regulatory mechanisms of comR, sitR, and sxvR were then analyzed by whole transcriptome RNA sequencing (RNA-Seq). Results indicated that the absence of comR induced the down-regulation of 17 virulence factors or virulence-related factors, including genes involved in the synthesis of capsules, oxidative stress tolerance, immune evasion, and cell division. Furthermore, three and two virulence factors or virulence-related factors were down-regulated upon deletion of sitR and sxvR, respectively. Thus, this study reports the discovery of three virulence-associated transcriptional regulatory factors in S.suis. These factors could ultimately be targeted to control infection caused by these bacteria.
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13
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Ni H, Li M, Wang Q, Wang J, Liu X, Zheng F, Hu D, Yu X, Han Y, Zhang Q, Zhou T, Wang Y, Wang C, Gao J, Shao ZQ, Pan X. Inactivation of the htpsA gene affects capsule development and pathogenicity of Streptococcus suis. Virulence 2020; 11:927-940. [PMID: 32815473 PMCID: PMC7567435 DOI: 10.1080/21505594.2020.1792080] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/04/2022] Open
Abstract
Streptococcus suis serotype 2 (S. suis 2) is an important swine pathogen and also an emerging zoonotic agent. HtpsA has been reported as an immunogenic cell surface protein on the bacterium. In the present study, we constructed an isogenic mutant strain of htpsA, namely ΔhtpsA, to study its role in the development and virulence of S. suis 2. Our results showed that the mutant strain lost its typical encapsulated structure with decreased concentrations of sialic acid. Furthermore, the survival rate in whole blood, the anti-phagocytosis by RAW264.7 murine macrophage, and the adherence ability to HEp-2 cells were all significantly affected in the ΔhtpsA. In addition, the deletion of htpsA sharply attenuated the virulence of S. suis 2 in an infection model of mouse. RNA-seq analysis revealed that 126 genes were differentially expressed between the ΔhtpsA and the wild-type strains, including 28 upregulated and 98 downregulated genes. Among the downregulated genes, many were involved in carbohydrate metabolism and synthesis of virulence-associated factors. Taken together, htpsA was demonstrated to play a role in the morphological development and pathogenesis of the highly virulent S. suis 2 05ZYH33 strain.
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Affiliation(s)
- Hua Ni
- Department of Microbiology, Hua Dong Research Institute for Medicine and Biotechnics , Nanjing, China.,Key Laboratory of Biological Resources and Ecology of Pamirs Plateau in Xinjiang Uygur Autonomous Region, College of Life and Geographic Sciences, Kashi University , Kashi, China
| | - Min Li
- Department of Microbiology, Hua Dong Research Institute for Medicine and Biotechnics , Nanjing, China.,Clinical Laboratory Department of Changzhi, People's Hospital , Changzhi, China
| | - Qiaoqiao Wang
- Department of Microbiology, Hua Dong Research Institute for Medicine and Biotechnics , Nanjing, China.,School of Life Sciences, Nanjing Normal University , Nanjing, China
| | - Jing Wang
- Department of Laboratory Medicine, The Affiliated Wuxi Maternity and Child Health Care Hospital of Nanjing Medical University , Wuxi, China
| | - Xumiao Liu
- Department of Microbiology, Hua Dong Research Institute for Medicine and Biotechnics , Nanjing, China.,School of Life Sciences, Nanjing Normal University , Nanjing, China
| | - Feng Zheng
- Department of Microbiology, Hua Dong Research Institute for Medicine and Biotechnics , Nanjing, China
| | - Dan Hu
- Department of Microbiology, Hua Dong Research Institute for Medicine and Biotechnics , Nanjing, China
| | - Xu Yu
- Department of Microbiology, Hua Dong Research Institute for Medicine and Biotechnics , Nanjing, China
| | - Yifang Han
- Department of Microbiology, Hua Dong Research Institute for Medicine and Biotechnics , Nanjing, China
| | - Qi Zhang
- Department of Microbiology, Hua Dong Research Institute for Medicine and Biotechnics , Nanjing, China
| | - Tingting Zhou
- Department of Microbiology, Hua Dong Research Institute for Medicine and Biotechnics , Nanjing, China
| | - Yiwen Wang
- Department of Microbiology, Hua Dong Research Institute for Medicine and Biotechnics , Nanjing, China
| | - Chunhui Wang
- Department of Microbiology, Hua Dong Research Institute for Medicine and Biotechnics , Nanjing, China
| | - Jimin Gao
- School of Laboratory Medicine and Life Science, Wenzhou Medical University , Wenzhou, China
| | - Zhu-Qing Shao
- Department of Microbiology, Hua Dong Research Institute for Medicine and Biotechnics , Nanjing, China.,State Key Laboratory of Pharmaceutical Biotechnology, School of Life Sciences, Nanjing University , Nanjing, China
| | - Xiuzhen Pan
- Department of Microbiology, Hua Dong Research Institute for Medicine and Biotechnics , Nanjing, China.,School of Life Sciences, Nanjing Normal University , Nanjing, China.,School of Laboratory Medicine and Life Science, Wenzhou Medical University , Wenzhou, China
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14
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Guo G, Wei D, Zhang Y, Wang K, Liu R, Wu Z, Kong L, Cheng L, Zhang W. M-like protein SrM is not crucial to the virulence of a novel isolate of Streptococcus equi subsp. ruminatorum from Macaca mulatta. Res Vet Sci 2020; 132:221-228. [PMID: 32615343 DOI: 10.1016/j.rvsc.2020.05.006] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2019] [Revised: 03/27/2020] [Accepted: 05/04/2020] [Indexed: 11/28/2022]
Abstract
In this study, a Streptococcus strainnamed FJ1804, was isolated from a blood sample collected from a dead Macaca mulatta in China and, was subsequently classified as Streptococcus equi subsp. ruminatorum (S.e. ruminatorum) through 16S rRNA gene sequence analysis. After whole genome sequencing and analysis, an M-like protein encoding gene that encodes an SrM protein that is homologous to the crucial S.e. zooepidemicus crucial virulence factor SzP, was identified in the genome of FJ1804. To determinethe function of SrM in this bacterium, a strain deleted of srm as well as a complement strain were constructed. The results of in vitro cell adherence, invasion and phagocytosis assays and in vivo animal challenge and histopathology showed that the anti-phagocytosis was decreased and the adherence rate was increased in the srm deletion strain, whereas the invasion rate, pathological features and LD50 values inboth zebrafish and BALB/c mice model showed no difference compared to that observed for the WT strain. To the best of our knowledge, this is first of an infection caused by S.e. ruminatorum, which is a newly identified zoonotic pathogen, in Macaca mulatta, and our data suggest that, compared with other S.e. zooepidemicus strains, the SzP homologous protein is not crucial to the virulence of this bacterium.
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Affiliation(s)
- Genglin Guo
- College of Veterinary Medicine, Nanjing Agricultural University, Nanjing 210095, China; Key Lab of Animal Bacteriology, Ministry of Agriculture, Nanjing 210095, China; OIE Reference Lab for Swine Streptococcosis, Nanjing 210095, China.
| | - Dan Wei
- College of Veterinary Medicine, Nanjing Agricultural University, Nanjing 210095, China; Key Lab of Animal Bacteriology, Ministry of Agriculture, Nanjing 210095, China; OIE Reference Lab for Swine Streptococcosis, Nanjing 210095, China.
| | - Yuhang Zhang
- College of Veterinary Medicine, Nanjing Agricultural University, Nanjing 210095, China; Key Lab of Animal Bacteriology, Ministry of Agriculture, Nanjing 210095, China; OIE Reference Lab for Swine Streptococcosis, Nanjing 210095, China.
| | - Kaicheng Wang
- China Animal Health and Epidemiology Center, Qingdao, Shandong, China.
| | - Rongchang Liu
- Institute of Animal Husbandry and Veterinary Medicine, Fujian Academy of Agricultural Sciences, Fuzhou, Fujian 350013, China.
| | - Zhiqiang Wu
- City Park Management Office of Nanping City, Nanping, Fujian 353000, China.
| | - Lifang Kong
- City Park Management Office of Nanping City, Nanping, Fujian 353000, China.
| | - Longfei Cheng
- Institute of Animal Husbandry and Veterinary Medicine, Fujian Academy of Agricultural Sciences, Fuzhou, Fujian 350013, China.
| | - Wei Zhang
- College of Veterinary Medicine, Nanjing Agricultural University, Nanjing 210095, China; Key Lab of Animal Bacteriology, Ministry of Agriculture, Nanjing 210095, China; OIE Reference Lab for Swine Streptococcosis, Nanjing 210095, China.
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15
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Arenas J, Bossers-de Vries R, Harders-Westerveen J, Buys H, Ruuls-van Stalle LMF, Stockhofe-Zurwieden N, Zaccaria E, Tommassen J, Wells JM, Smith HE, de Greeff A. In vivo transcriptomes of Streptococcus suis reveal genes required for niche-specific adaptation and pathogenesis. Virulence 2020; 10:334-351. [PMID: 30957693 PMCID: PMC6527017 DOI: 10.1080/21505594.2019.1599669] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Streptococcus suis is a Gram-positive bacterium and a zoonotic pathogen residing in the nasopharynx or the gastrointestinal tract of pigs with a potential of causing life-threatening invasive disease. It is endemic in the porcine production industry worldwide, and it is also an emerging human pathogen. After invasion, the pathogen adapts to cause bacteremia and disseminates to different organs including the brain. To gain insights in this process, we infected piglets with a highly virulent strain of S. suis, and bacterial transcriptomes were obtained from blood and different organs (brain, joints, and heart) when animals had severe clinical symptoms of infection. Microarrays were used to determine the genome-wide transcriptional profile at different infection sites and during growth in standard growth medium in vitro. We observed differential expression of around 30% of the Open Reading Frames (ORFs) and infection-site specific patterns of gene expression. Genes with major changes in expression were involved in transcriptional regulation, metabolism, nutrient acquisition, stress defenses, and virulence, amongst others, and results were confirmed for a subset of selected genes using RT-qPCR. Mutants were generated in two selected genes, and the encoded proteins, i.e., NADH oxidase and MetQ, were shown to be important virulence factors in coinfection experiments and in vitro assays. The knowledge derived from this study regarding S. suis gene expression in vivo and identification of virulence factors is important for the development of novel diagnostic and therapeutic strategies to control S. suis disease.
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Affiliation(s)
- Jesús Arenas
- a Department of Infection Biology , Wageningen BioVeterinary Research (WBVR) , Lelystad , The Netherlands
| | - Ruth Bossers-de Vries
- a Department of Infection Biology , Wageningen BioVeterinary Research (WBVR) , Lelystad , The Netherlands
| | - José Harders-Westerveen
- a Department of Infection Biology , Wageningen BioVeterinary Research (WBVR) , Lelystad , The Netherlands
| | - Herma Buys
- a Department of Infection Biology , Wageningen BioVeterinary Research (WBVR) , Lelystad , The Netherlands
| | | | | | - Edoardo Zaccaria
- b Host Microbe Interactions , Wageningen UR , Wageningen , The Netherlands
| | - Jan Tommassen
- c Department of Molecular Microbiology and Institute of Biomembranes , Utrecht University , Utrecht , The Netherlands
| | - Jerry M Wells
- b Host Microbe Interactions , Wageningen UR , Wageningen , The Netherlands
| | - Hilde E Smith
- a Department of Infection Biology , Wageningen BioVeterinary Research (WBVR) , Lelystad , The Netherlands
| | - Astrid de Greeff
- a Department of Infection Biology , Wageningen BioVeterinary Research (WBVR) , Lelystad , The Netherlands
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16
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Virulence Factors of Meningitis-Causing Bacteria: Enabling Brain Entry across the Blood-Brain Barrier. Int J Mol Sci 2019; 20:ijms20215393. [PMID: 31671896 PMCID: PMC6862235 DOI: 10.3390/ijms20215393] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2019] [Revised: 10/24/2019] [Accepted: 10/25/2019] [Indexed: 12/16/2022] Open
Abstract
Infections of the central nervous system (CNS) are still a major cause of morbidity and mortality worldwide. Traversal of the barriers protecting the brain by pathogens is a prerequisite for the development of meningitis. Bacteria have developed a variety of different strategies to cross these barriers and reach the CNS. To this end, they use a variety of different virulence factors that enable them to attach to and traverse these barriers. These virulence factors mediate adhesion to and invasion into host cells, intracellular survival, induction of host cell signaling and inflammatory response, and affect barrier function. While some of these mechanisms differ, others are shared by multiple pathogens. Further understanding of these processes, with special emphasis on the difference between the blood-brain barrier and the blood-cerebrospinal fluid barrier, as well as virulence factors used by the pathogens, is still needed.
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17
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Auger JP, Payen S, Roy D, Dumesnil A, Segura M, Gottschalk M. Interactions of Streptococcus suis serotype 9 with host cells and role of the capsular polysaccharide: Comparison with serotypes 2 and 14. PLoS One 2019; 14:e0223864. [PMID: 31600314 PMCID: PMC6786723 DOI: 10.1371/journal.pone.0223864] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2019] [Accepted: 09/30/2019] [Indexed: 12/21/2022] Open
Abstract
Streptococcus suis is an important porcine bacterial pathogen and a zoonotic agent responsible for sudden death, septic shock and meningitis, of which serotype 2 is the most widespread, with serotype 14 also causing infections in humans in South-East Asia. Knowledge of its pathogenesis and virulence are almost exclusively based on these two serotypes. Though serotype 9 is responsible for the greatest number of porcine cases in Spain, the Netherlands and Germany, very little information is currently available regarding this serotype. Of the different virulence factors, the capsular polysaccharide (CPS) is required for S. suis virulence as it promotes resistance to phagocytosis and killing and masks surface components responsible for host cell activation. However, these roles have been described for serotypes 2 and 14, whose CPSs are structurally and compositionally similar, both containing sialic acid. Consequently, we evaluated herein the interactions of serotype 9 with host cells and the role of its CPS, which greatly differs from those of serotypes 2 and 14. Results demonstrated that serotype 9 adhesion to but not invasion of respiratory epithelial cells was greater than that of serotypes 2 and 14. Furthermore serotype 9 was more internalized by macrophages but equally resistant to whole blood killing. Though recognition of serotypes 2, 9 and 14 by DCs required MyD88-dependent signaling, in vitro pro-inflammatory mediator production induced by serotype 9 was much lower. In vivo, however, serotype 9 causes an exacerbated inflammatory response, which combined with persistent bacterial presence, is probably responsible for host death during the systemic infection. Though presence of the serotype 9 CPS masks surface components less efficiently than those of serotypes 2 and 14, the serotype 9 CPS remains critical for virulence as it is required for survival in blood and development of clinical disease, and this regardless of its unique composition and structure.
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Affiliation(s)
- Jean-Philippe Auger
- Research Group on Infectious Diseases in Production Animals (GREMIP) and Swine and Poultry Infectious Diseases Research Center (CRIPA), Department of Pathology and Microbiology, Faculty of Veterinary Medicine, Université de Montréal, Saint-Hyacinthe, Quebec, Canada
| | - Servane Payen
- Research Group on Infectious Diseases in Production Animals (GREMIP) and Swine and Poultry Infectious Diseases Research Center (CRIPA), Department of Pathology and Microbiology, Faculty of Veterinary Medicine, Université de Montréal, Saint-Hyacinthe, Quebec, Canada
| | - David Roy
- Research Group on Infectious Diseases in Production Animals (GREMIP) and Swine and Poultry Infectious Diseases Research Center (CRIPA), Department of Pathology and Microbiology, Faculty of Veterinary Medicine, Université de Montréal, Saint-Hyacinthe, Quebec, Canada
| | - Audrey Dumesnil
- Research Group on Infectious Diseases in Production Animals (GREMIP) and Swine and Poultry Infectious Diseases Research Center (CRIPA), Department of Pathology and Microbiology, Faculty of Veterinary Medicine, Université de Montréal, Saint-Hyacinthe, Quebec, Canada
| | - Mariela Segura
- Research Group on Infectious Diseases in Production Animals (GREMIP) and Swine and Poultry Infectious Diseases Research Center (CRIPA), Department of Pathology and Microbiology, Faculty of Veterinary Medicine, Université de Montréal, Saint-Hyacinthe, Quebec, Canada
| | - Marcelo Gottschalk
- Research Group on Infectious Diseases in Production Animals (GREMIP) and Swine and Poultry Infectious Diseases Research Center (CRIPA), Department of Pathology and Microbiology, Faculty of Veterinary Medicine, Université de Montréal, Saint-Hyacinthe, Quebec, Canada
- * E-mail:
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18
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Identification of an Autorepressing Two-Component Signaling System That Modulates Virulence in Streptococcus suis Serotype 2. Infect Immun 2019; 87:IAI.00377-19. [PMID: 31285250 DOI: 10.1128/iai.00377-19] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2019] [Accepted: 06/26/2019] [Indexed: 12/17/2022] Open
Abstract
Streptococcus suis is one of the most important pathogens affecting the swine industry and is also an emerging zoonotic agent for humans. Two-component signaling systems (TCSs) play important roles in the adaptation of pathogenic bacteria to host environments. In this study, we identified a novel TCS, named TCS09HKRR, which facilitated Streptococcus suis serotype 2 (SS2) resistance to clearance by the host immune system and contributed to bacterial pathogenicity. Furthermore, RNA-sequencing analyses identified 79 genes that were differentially expressed between the wild-type (WT) and ΔTCS09HKRR strains, among which half of the 39 downregulated genes belonged to the capsular biosynthesis clusters. Transmission electron microscopy confirmed that the capsule of the ΔTCS09HKRR strain was thinner than that of the WT strain. Electrophoretic mobility shift assays (EMSA) showed that the regulator of TCS09HKRR (TCS09RR) could not bind the promoter regions of cps and neu clusters, which suggested that TCS09HKRR regulates capsule biosynthesis by indirect pathways. Unexpectedly, the TCS09HKRR operon was upregulated when TCS09HKRR was deleted. A specific region, ATGACATTTGTCAC, which extends from positions -193 to -206 upstream of the TCS09HKRR operon, was further identified as the TCS09RR-binding site using EMSA. These results suggested the involvement of a negative feedback loop in this regulation. In addition, TCS09RR was significantly upregulated by more than 18-fold when coincubated with RAW264.7 macrophages. Our data suggested that autorepression renders TCS09HKRR more sensitive to host stimuli, which optimizes the regulatory network of capsular biosynthesis in SS2.
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The Arginine Deiminase Operon Is Responsible for a Fitness Trade-Off in Extended-Spectrum-β-Lactamase-Producing Strains of Escherichia coli. Antimicrob Agents Chemother 2019; 63:AAC.00635-19. [PMID: 31138573 DOI: 10.1128/aac.00635-19] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2019] [Accepted: 05/20/2019] [Indexed: 02/06/2023] Open
Abstract
We previously identified an operon involved in an arginine deiminase (ADI) pathway (arc operon) on a CTX-M-producing plasmid from an O102-ST405 strain of Escherichia coli As the ADI pathway was shown to be involved in the virulence of various Gram-positive bacteria, we tested whether the ADI pathway could be involved in the epidemiological success of extended-spectrum-β-lactamase (ESBL)-producing E. coli strains. We studied two collections of human E. coli isolated in France (n = 493) and England (n = 1,509) and show that the prevalence of the arc operon (i) is higher in ESBL-producing strains (12.1%) than in nonproducers (2.5%), (ii) is higher in CTX-M-producing strains (16%) than in other ESBL producers (3.5%), and (iii) increased over time in ESBL-producing strains from 0% before 2000 to 43.3% in 2011 to 2012. The arc operon, found in strains from various phylogenetic backgrounds, is carried by IncF plasmids (85%) or chromosomes (15%) in regions framed by numerous insertion sequences, indicating multiple arrivals. Competition experiments showed that the arc operon enhances fitness of the strain in vitro in lysogeny broth with arginine. In vivo competition experiments showed that the arc operon is advantageous for the strain in a mouse model of urinary tract infection (UTI), whereas it is a burden in a mouse model of intestinal colonization. In summary, we have identified a trait linked to CTX-M-producing strains that is responsible for a trade-off between two main E. coli lifestyles, UTI and gut commensalism. This trait alone cannot explain the wide spread of ESBLs in E. coli but merits epidemiological surveillance.
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Role of the Endocytosis of Caveolae in Intracellular Signaling and Metabolism. PROGRESS IN MOLECULAR AND SUBCELLULAR BIOLOGY 2019; 57:203-234. [PMID: 30097777 DOI: 10.1007/978-3-319-96704-2_8] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Caveolae are 60-80 nm invaginated plasma membrane (PM) nanodomains, with a specific lipid and protein composition, which assist and regulate multiple processes in the plasma membrane-ranging from the organization of signalling complexes to the mechanical adaptation to changes in PM tension. However, since their initial descriptions, these structures have additionally been found tightly linked to internalization processes, mechanoadaptation, to the regulation of signalling events and of endosomal trafficking. Here, we review caveolae biology from this perspective, and its implications for cell physiology and disease.
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Prüfer TL, Rohde J, Verspohl J, Rohde M, de Greeff A, Willenborg J, Valentin-Weigand P. Molecular typing of Streptococcus suis strains isolated from diseased and healthy pigs between 1996-2016. PLoS One 2019; 14:e0210801. [PMID: 30653570 PMCID: PMC6336254 DOI: 10.1371/journal.pone.0210801] [Citation(s) in RCA: 38] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2018] [Accepted: 01/02/2019] [Indexed: 11/18/2022] Open
Abstract
Streptococcus suis is an economically important pathogen of pigs as well as a zoonotic cause of human disease. Serotyping is used for further characterization of isolates; some serotypes seem to be more virulent and more widely spread than others. This study characterizes a collection of German field isolates of Streptococcus suis from pigs dating from 1996 to 2016 with respect to capsular genes (cps) specific for individual serotypes and pathotype by multiplex PCR and relates results to the clinical background of these isolates. The most prominent finding was the reduction in prevalence of serotype-2/serotype-1/2 among invasive isolates during this sampling period, which might be attributed to widely implemented autogenous vaccination programs in swine against serotype 2 in Germany. In diseased pigs (systemically ill; respiratory disease) isolates of serotype-1/serotype-14, serotype-2/serotype-1/2, serotype 3 to 5 and 7 to 9 were most frequent while in carrier isolates a greater variety of cps types was found. Serotype-1/serotype-14 seemed to be preferentially located in joints, serotype 4 and serotype 3 in the central nervous system, respectively. The virulence associated extracellular protein factor was almost exclusively associated with invasive serotype-1/serotype-14 and serotype-2/serotype-1/2 isolates. In contrast, lung isolates of serotype-2/serotype-1/2 mainly harbored the gene for muramidase-released protein. Serotype 4 and serotype 9 isolates from clinically diseased pigs most frequently carried the muramidase-released protein gene and the suilysin gene. When examined by transmission electron microscopy all but one of the isolates which were non-typable by molecular and serological methods showed various amounts of capsular material indicating potentially new serotypes among these isolates. Given the variety of cps types/serotypes detected in pigs, not only veterinarians but also medical doctors should consider other serotypes than just serotype 2 when investigating potential human cases of Streptococcus suis infection.
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Affiliation(s)
- T. Louise Prüfer
- Institute for Microbiology, University of Veterinary Medicine, Hannover, Germany
| | - Judith Rohde
- Institute for Microbiology, University of Veterinary Medicine, Hannover, Germany
- * E-mail:
| | - Jutta Verspohl
- Institute for Microbiology, University of Veterinary Medicine, Hannover, Germany
| | - Manfred Rohde
- Central Facility for Microscopy, Helmholtz Centre for Infection Research, Braunschweig, Germany
| | | | - Jörg Willenborg
- Institute for Microbiology, University of Veterinary Medicine, Hannover, Germany
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Qian Y, Zhang Y, Yu Y, Li Q, Guo G, Fu Y, Yao H, Lu C, Zhang W. SBP1 is an adhesion-associated factor without the involvement of virulence in Streptococcus suis serotype 2. Microb Pathog 2018; 122:90-97. [DOI: 10.1016/j.micpath.2018.06.008] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2018] [Revised: 05/22/2018] [Accepted: 06/06/2018] [Indexed: 11/29/2022]
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The Two-Component Signaling System VraSR ss Is Critical for Multidrug Resistance and Full Virulence in Streptococcus suis Serotype 2. Infect Immun 2018; 86:IAI.00096-18. [PMID: 29685990 DOI: 10.1128/iai.00096-18] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2018] [Accepted: 04/18/2018] [Indexed: 11/20/2022] Open
Abstract
Streptococcus suis has received increasing attention for its involvement in severe human infections worldwide as well as in multidrug resistance. Two-component signaling systems (TCSSs) play important roles in bacterial adaptation to various environmental stimuli. In this study, we identified a novel TCSS located in S. suis serotype 2 (SS2), designated VraSRSS, which is involved in bacterial pathogenicity and susceptibility to antimicrobials. Our data demonstrated that the yvqFSS gene, located upstream of vraSRSS , shared the same promoter with the TCSS genes, which was directly regulated by VraSRSS, as shown in electrophoretic mobility shift assays. Notably, YvqFSS and VraSRSS constitute a novel multidrug resistance module of SS2 that participates in resistance to certain groups of antimicrobials. Further analyses showed that VraSRSS inactivation significantly attenuated bacterial virulence in animal models, which, coupled with the significant activation of VraSRSS expression observed in host blood, strongly suggested that VraSRSS is an important regulator of SS2 pathogenicity. Indeed, RNA-sequencing analyses identified 106 genes that were differentially expressed between the wild-type and ΔvraSRSS strains, including genes involved in capsular polysaccharide (CPS) biosynthesis. Subsequent studies confirmed that VraSRSS indirectly regulated the transcription of CPS gene clusters and, thus, controlled the CPS thickness shown by transmission electron microscopy. Decreased CPS biosynthesis caused by vraSRSS deletion subsequently increased bacterial adhesion to epithelial cells and attenuated antiphagocytosis against macrophages, which partially clarified the pathogenic mechanism mediated by VraSRSS Taken together, our data suggest that the novel TCSS, VraSRSS, plays critical roles for multidrug resistance and full virulence in SS2.
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Vötsch D, Willenborg M, Weldearegay YB, Valentin-Weigand P. Streptococcus suis - The "Two Faces" of a Pathobiont in the Porcine Respiratory Tract. Front Microbiol 2018; 9:480. [PMID: 29599763 PMCID: PMC5862822 DOI: 10.3389/fmicb.2018.00480] [Citation(s) in RCA: 74] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2017] [Accepted: 02/28/2018] [Indexed: 11/16/2022] Open
Abstract
Streptococcus (S.) suis is a frequent early colonizer of the upper respiratory tract of pigs. In fact, it is difficult to find S. suis-free animals under natural conditions, showing the successful adaptation of this pathogen to its porcine reservoir host. On the other hand, S. suis can cause life-threatening diseases and represents the most important bacterial cause of meningitis in pigs worldwide. Notably, S. suis can also cause zoonotic infections, such as meningitis, septicemia, endocarditis, and other diseases in humans. In Asia, it is classified as an emerging zoonotic pathogen and currently considered as one of the most important causes of bacterial meningitis in adults. The “two faces” of S. suis, one of a colonizing microbe and the other of a highly invasive pathogen, have raised many questions concerning the interpretation of diagnostic detection and the definition of virulence. Thus, one major research challenge is the identification of virulence-markers which allow differentiation of commensal and virulent strains. This is complicated by the high phenotypic and genotypic diversity of S. suis, as reflected by the occurrence of (at least) 33 capsular serotypes. In this review, we present current knowledge in the context of S. suis as a highly diverse pathobiont in the porcine respiratory tract that can exploit disrupted host homeostasis to flourish and promote inflammatory processes and invasive diseases in pigs and humans.
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Affiliation(s)
- Désirée Vötsch
- Institute for Microbiology, Center for Infection Medicine, University of Veterinary Medicine Hannover, Hannover, Germany
| | - Maren Willenborg
- Institute for Microbiology, Center for Infection Medicine, University of Veterinary Medicine Hannover, Hannover, Germany
| | - Yenehiwot B Weldearegay
- Institute for Microbiology, Center for Infection Medicine, University of Veterinary Medicine Hannover, Hannover, Germany
| | - Peter Valentin-Weigand
- Institute for Microbiology, Center for Infection Medicine, University of Veterinary Medicine Hannover, Hannover, Germany
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Auger JP, Meekhanon N, Okura M, Osaki M, Gottschalk M, Sekizaki T, Takamatsu D. Streptococcus suis Serotype 2 Capsule In Vivo. Emerg Infect Dis 2018; 22:1793-6. [PMID: 27648583 PMCID: PMC5038428 DOI: 10.3201/eid2210.151640] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Many Streptococcus suis isolates from porcine endocarditis in slaughterhouses have lost their capsule and are considered avirulent. However, we retrieved capsule- and virulence-recovered S. suis after in vivo passages of a nonencapsulated strain in mice, suggesting that nonencapsulated S. suis are still potentially hazardous for persons in the swine industry.
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Tong J, Fu Y, Wu NH, Rohde M, Meng F, Valentin-Weigand P, Herrler G. Sialic acid-dependent interaction of group B streptococci with influenza virus-infected cells reveals a novel adherence and invasion mechanism. Cell Microbiol 2018; 20. [DOI: 10.1111/cmi.12818] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2017] [Revised: 11/10/2017] [Accepted: 12/01/2017] [Indexed: 12/26/2022]
Affiliation(s)
- Jie Tong
- Institute of Virology; University of Veterinary Medicine Hannover; Hannover Germany
| | - Yuguang Fu
- Institute of Virology; University of Veterinary Medicine Hannover; Hannover Germany
- Chinese Academy of Agricultural Sciences, Lanzhou Veterinary Research Institute; State Key Laboratory of Veterinary Etiological Biology; Lanzhou Gansu Province China
| | - Nai-Huei Wu
- Institute of Virology; University of Veterinary Medicine Hannover; Hannover Germany
| | - Manfred Rohde
- Central Facility for Microscopy; Helmholtz Centre for Infection Research, HZI; Braunschweig Germany
| | - Fandan Meng
- Institute of Virology; University of Veterinary Medicine Hannover; Hannover Germany
| | | | - Georg Herrler
- Institute of Virology; University of Veterinary Medicine Hannover; Hannover Germany
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Skive B, Rohde M, Molinari G, Braunstein TH, Bojesen AM. Streptococcus equi subsp. zooepidemicus Invades and Survives in Epithelial Cells. Front Cell Infect Microbiol 2017; 7:465. [PMID: 29164073 PMCID: PMC5681531 DOI: 10.3389/fcimb.2017.00465] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2017] [Accepted: 10/20/2017] [Indexed: 12/22/2022] Open
Abstract
Streptococcus equi subsp. zooepidemicus (S. zooepidemicus) is an opportunistic pathogen of several species including humans. S. zooepidemicus is found on mucus membranes of healthy horses, but can cause acute and chronic endometritis. Recently S. zooepidemicus was found able to reside in the endometrium for prolonged periods of time. Thus, we hypothesized that an intracellular phase may be part of the S. zooepidemicus pathogenesis and investigated if S. zooepidemicus was able to invade and survive inside epithelial cells. HEp-2 and HeLa cell lines were co-cultured with two S. zooepidemicus strains (1-4a and S31A1) both originating from the uterus of mares suffering from endometritis. Cells were fixed at different time points during the 23 h infection assay and field emission scanning electron microscopy (FESEM) was used to characterize adhesion and invasion mechanisms. The FESEM images showed three morphologically different types of invasion for both bacterial strains. The main port of entry was through large invaginations in the epithelial cell membrane. Pili-like bacterial appendages were observed when the S. zooepidemicus cells were in close proximity to the epithelial cells indicating that attachment and invasion were active processes. Adherent and intracellular S. zooepidemicus, and bacteria in association with lysosomes was determined by immunofluorescence staining techniques and fluorescence microscopy. Quantification of intracellular bacteria was determined in penicillin protection assays. Both S. zooepidemicus strains investigated were able to invade epithelial cells although at different magnitudes. The immunofluorescence data showed significantly higher adhesion and invasion rates for strain 1-4a when compared to strain S31A1. S. zooepidemicus was able to survive intracellularly, but the survival rate decreased over time in the cell culture system. Phagosome-like compartments containing S. zooepidemicus at some stages fused with lysosomes to form a phagolysosome. The results indicate that an intracellular phase may be one way S. zooepidemicus survives in the host, and could in part explain how S. zooepidemicus can cause recurrent/persistent infections. Future studies should reveal the ability of S. zooepidemicus to internalize and survive in primary equine endometrial cells and during in vivo conditions.
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Affiliation(s)
- Bolette Skive
- Veterinary Clinical Microbiology, Department of Veterinary and Animal Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Frederiksberg, Denmark
| | - Manfred Rohde
- Central Facility for Microscopy, Helmholtz Centre for Infection Research, Braunschweig, Germany
| | - Gabriella Molinari
- Central Facility for Microscopy, Helmholtz Centre for Infection Research, Braunschweig, Germany
| | - Thomas Hartig Braunstein
- Core Facility for Integrated Microscopy, Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Anders M Bojesen
- Veterinary Clinical Microbiology, Department of Veterinary and Animal Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Frederiksberg, Denmark
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Maneerat K, Yongkiettrakul S, Jiemsup S, Tongtawe P, Gottschalk M, Srimanote P. Expression and Characterization of Serotype 2 Streptococcus suis Arginine Deiminase. J Mol Microbiol Biotechnol 2017; 27:133-146. [PMID: 28456803 DOI: 10.1159/000452952] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2016] [Accepted: 10/25/2016] [Indexed: 01/22/2023] Open
Abstract
BACKGROUND Arginine deiminase (ArcA) has been speculated to facilitate the intracellular survival of Streptococcus suis under acidic conditions. However, the physical and biological properties and function of SS2-ArcA have not yet been elucidated. METHODS Recombinant SS2-ArcA (rSS2-ArcA) was expressed and purified using Ni-NTA affinity chromatography. Under various pH and temperature conditions, the enzymatic properties of purified rSS2-ArcA and crude native SS2-ArcA were determined. RESULTS The SS2-arcA-deduced amino acid sequence contained a conserved catalytic triad (Cys399-His273-Glu218). The optimum temperature and pH of 47-kDa rSS2-ArcA and crude native SS2-ArcA were 42°C and pH 7.2. The rSS2-ArcA and crude native SS2-ArcA were stable for 3 h at 4 and 25°C, respectively. The pH stability and dependency tests suggested that rSS2-ArcA and crude native SS2-ArcA were functionally active in acidic conditions. The L-arginine substrate binding affinity (Km) values of rSS2-ArcA (specific activity 16.00 U/mg) and crude native SS2-ArcA (specific activity 0.23 U/mg) were 0.058 and 0.157 mM, respectively. rSS2-ArcA exhibited a weak binding affinity with the common ArcA inhibitors L-canavanine and L-NIO. Furthermore, the partial inactivation of SS2-ArcA significantly impaired the viability and growth of SS2 at pH 4.0, 6.0, and 7.5. CONCLUSIONS This study profoundly demonstrated the involvement of ArcA enzymatic activity in S. suis survival under acidic conditions.
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Affiliation(s)
- Krissana Maneerat
- Graduate Program in Biomedical Sciences, Faculty of Allied Health Sciences, Thammasat University, Pathumthani, Thailand
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Ferrando ML, Willemse N, Zaccaria E, Pannekoek Y, van der Ende A, Schultsz C. Streptococcal Adhesin P (SadP) contributes to Streptococcus suis adhesion to the human intestinal epithelium. PLoS One 2017; 12:e0175639. [PMID: 28407026 PMCID: PMC5391093 DOI: 10.1371/journal.pone.0175639] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2016] [Accepted: 03/29/2017] [Indexed: 12/30/2022] Open
Abstract
Background Streptococcus suis is a zoonotic pathogen, causing meningitis and septicemia. We previously demonstrated that the gastrointestinal tract (GIT) is an entry site for zoonotic S. suis infection. Here we studied the contribution of Streptococcal adhesin Protein (SadP) to host-pathogen interaction at GIT level. Methods SadP expression in presence of Intestinal Epithelial Cells (IEC) was compared with expression of other virulence factors by measuring transcript levels using quantitative Real Time PCR (qRT-PCR). SadP variants were identified by phylogenetic analysis of complete DNA sequences. The interaction of SadP knockout and complementation mutants with IEC was tested in vitro. Results Expression of sadP was significantly increased in presence of IEC. Sequence analysis of 116 invasive strains revealed five SadP sequence variants, correlating with genotype. SadP1, present in zoonotic isolates of clonal complex 1, contributed to binding to both human and porcine IEC and translocation across human IEC. Antibodies against the globotriaosylceramide Gb3/CD77 receptor significantly inhibited adhesion to human IEC. Conclusion SadP is involved in the host-pathogen interaction in the GIT. Differences between SadP variants may determine different affinities to the Gb3/CD77 host-receptor, contributing to variation in adhesion capacity to host IEC and thus to S. suis zoonotic potential.
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Affiliation(s)
- Maria Laura Ferrando
- Department of Medical Microbiology, Center for Infection and Immunity, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
- Department of Global Health-Amsterdam Institute for Global Health and Development, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
- * E-mail:
| | - Niels Willemse
- Department of Medical Microbiology, Center for Infection and Immunity, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
- Department of Global Health-Amsterdam Institute for Global Health and Development, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
| | - Edoardo Zaccaria
- Host-Microbe Interactomics, Animal Sciences, Wageningen University, Wageningen, The Netherlands
| | - Yvonne Pannekoek
- Department of Medical Microbiology, Center for Infection and Immunity, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
| | - Arie van der Ende
- Department of Medical Microbiology, Center for Infection and Immunity, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
| | - Constance Schultsz
- Department of Medical Microbiology, Center for Infection and Immunity, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
- Department of Global Health-Amsterdam Institute for Global Health and Development, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
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Critical Streptococcus suis Virulence Factors: Are They All Really Critical? Trends Microbiol 2017; 25:585-599. [PMID: 28274524 DOI: 10.1016/j.tim.2017.02.005] [Citation(s) in RCA: 167] [Impact Index Per Article: 23.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2016] [Revised: 01/30/2017] [Accepted: 02/09/2017] [Indexed: 01/15/2023]
Abstract
Streptococcus suis is an important swine pathogen that can be transmitted to humans by contact with diseased animals or contaminated raw pork products. This pathogen possesses a coat of capsular polysaccharide (CPS) that confers protection against the immune system. Yet, the CPS is not the only virulence factor enabling this bacterium to successfully colonize, invade, and disseminate in its host leading to severe systemic diseases such as meningitis and toxic shock-like syndrome. Indeed, recent research developments, cautiously inventoried in this review, have revealed over 100 'putative virulence factors or traits' (surface-associated or secreted components, regulatory genes or metabolic pathways), of which at least 37 have been claimed as being 'critical' for virulence. In this review we discuss the current contradictions and controversies raised by this explosion of virulence factors and the future directions that may be conceived to advance and enlighten research on S. suis pathogenesis.
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Bai J, Yang Y, Wang S, Gao L, Chen J, Ren Y, Ding W, Muhammad I, Li Y. Syringa oblata Lindl. Aqueous Extract Is a Potential Biofilm Inhibitor in S. suis. Front Pharmacol 2017; 8:26. [PMID: 28194111 PMCID: PMC5278344 DOI: 10.3389/fphar.2017.00026] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2016] [Accepted: 01/16/2017] [Indexed: 11/13/2022] Open
Abstract
Streptococcus suis (S. suis) is a zoonotic pathogen that causes severe disease symptoms in pigs and humans. Syringa oblata Lindl. distributed in the middle latitudes of Eurasia and North America were proved as the most development potential of Chinese Medicine. In this study, biofilm formation by S. suis decreased after growth with 1/2 MIC, 1/4 MIC, or 1/8 MIC of Syringa oblata Lindl. aqueous extract and rutin. Scanning electron microscopy analysis revealed the potential effect of Syringa oblata Lindl. aqueous extract and rutin against biofilm formation by S. suis. Using iTRAQ technology, comparative proteomic analyses was performed at two conditions: 1/2 MIC of Syringa oblata Lindl. aqueous extract treated and non-treated cells. The results revealed the existence of 28 proteins of varying amounts. We found that the majority of the proteins were related to cell growth and metabolism. We also found that Syringa oblata Lindl. Aqueous extract affected the synthesis enzymes. In summary, Syringa oblata Lindl. aqueous extract might be used to inhibit the biofilm formation effectively by S. suis, and the active ingredients of the Syringa oblate Lindl. aqueous extract is rutin. The content of rutin is 9.9 ± 0.089 mg/g dry weight.
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Affiliation(s)
- Jingwen Bai
- College of Veterinary Medicine, Northeast Agricultural University Harbin, China
| | - Yanbei Yang
- College of Veterinary Medicine, Northeast Agricultural University Harbin, China
| | - Shuai Wang
- College of Veterinary Medicine, Northeast Agricultural University Harbin, China
| | - Lingfei Gao
- College of Veterinary Medicine, Northeast Agricultural University Harbin, China
| | - Jianqing Chen
- College of Veterinary Medicine, Northeast Agricultural University Harbin, China
| | - Yongzhi Ren
- College of Veterinary Medicine, Northeast Agricultural University Harbin, China
| | - Wenya Ding
- College of Veterinary Medicine, Northeast Agricultural University Harbin, China
| | - Ishfaq Muhammad
- College of Veterinary Medicine, Northeast Agricultural University Harbin, China
| | - Yanhua Li
- College of Veterinary Medicine, Northeast Agricultural University Harbin, China
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Techawiwattanaboon T, Chareonsudjai S. A predicted cation transporter protein, BPSS1228, is involved in intracellular behaviour of Burkholderia pseudomallei in a human lung epithelial cell line (A549). FEMS Microbiol Lett 2016; 363:fnw259. [PMID: 28003338 DOI: 10.1093/femsle/fnw259] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Revised: 06/10/2016] [Accepted: 11/10/2016] [Indexed: 12/15/2022] Open
Abstract
Burkholderia pseudomallei causes melioidosis, a potentially fatal infectious disease in tropical and subtropical countries worldwide. The intracellular behaviour of this pathogen in host cells has been reported to impact the severity of melioidosis, including the development of septicaemia, a consequence of pneumonia melioidosis. We previously identified a predicted cation transporter protein, BPSS1228, that participates in the transitional stage of this intracellular pathogen. For further analysis, in this study B. pseudomallei bpss1228 mutant and complemented strains were constructed and bacterial infectivity on human lung epithelial cells, A549, investigated in vitro Burkholderia pseudomallei bpss1228 mutant showed impaired bacterial adhesion and invasion into A549 cells compared with wild-type strain, while the deficient phenotypes were restored to wild-type levels by the complemented strain. Additionally, the inactivation of bpss1228 in the mutant strain affected flagella-based swimming on a semi-solid surface and resistance to acid stresses simulating intracellular environments. These observations of BPSS1228 relating to B. pseudomallei infection strategies shed a new light on its association with intracellular B. pseudomallei during the interaction with host cells.
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Affiliation(s)
- Teerasit Techawiwattanaboon
- Department of Microbiology, Faculty of Medicine, Melioidosis Research Center and Biofilm Research Group, Khon Kaen University, Khon Kaen, Thailand
| | - Sorujsiri Chareonsudjai
- Department of Microbiology, Faculty of Medicine, Melioidosis Research Center and Biofilm Research Group, Khon Kaen University, Khon Kaen, Thailand
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Jiang X, Yang Y, Zhou J, Zhu L, Gu Y, Zhang X, Li X, Fang W. Roles of the Putative Type IV-like Secretion System Key Component VirD4 and PrsA in Pathogenesis of Streptococcus suis Type 2. Front Cell Infect Microbiol 2016; 6:172. [PMID: 27995095 PMCID: PMC5133265 DOI: 10.3389/fcimb.2016.00172] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2016] [Accepted: 11/17/2016] [Indexed: 12/19/2022] Open
Abstract
Streptococcus suis type 2 (SS2) is a zoonotic pathogen causing septic infection, meningitis and pneumonia in pigs and humans. SS2 may cause streptococcal toxic shock syndrome (STSS) probably due to excessive release of inflammatory cytokines. A previous study indicated that the virD4 gene in the putative type IV-like secretion system (T4SS) within the 89K pathogenicity island specific for recent epidemic strains contributed to the development of STSS. However, the functional basis of VirD4 in STSS remains unclear. Here we show that deletion of virD4 led to reduced virulence as shown by about 65% higher LD50, lower bacterial load in liver and brain, and lower level of expression of inflammatory cytokines in mice and cell lines than its parent strain. The ΔVirD4 mutant was more easily phagocytosed, suggesting its role as an anti-phagocytic factor. Oxidative stress that mimic bacterial exposure to respiratory burst of phagocytes upregulated expression of virD4. Proteomic analysis identified 10 secreted proteins of significant differences between the parent and mutant strains under oxidative stress, including PrsA, a peptidyl-prolyl isomerase. The SS2 PrsA expressed in E. coli caused a dose-dependent cell death and increased expression of proinflammatory IL-1β, IL-6 and TNF-α in murine macrophage cells. Our data provide novel insights into the contribution of the VirD4 factor to STSS pathogenesis, possibly via its anti-phagocytic activity, upregulation of its expression upon oxidative stress and its involvement in increased secretion of PrsA as a cell death inducer and proinflammatory effector.
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Affiliation(s)
- Xiaowu Jiang
- Zhejiang University Institute of Preventive Veterinary Medicine, and Zhejiang Provincial Key Laboratory of Preventive Veterinary Medicine Zhejiang, China
| | - Yunkai Yang
- Zhejiang University Institute of Preventive Veterinary Medicine, and Zhejiang Provincial Key Laboratory of Preventive Veterinary Medicine Zhejiang, China
| | - Jingjing Zhou
- Zhejiang University Institute of Preventive Veterinary Medicine, and Zhejiang Provincial Key Laboratory of Preventive Veterinary Medicine Zhejiang, China
| | - Lexin Zhu
- Zhejiang University Institute of Preventive Veterinary Medicine, and Zhejiang Provincial Key Laboratory of Preventive Veterinary Medicine Zhejiang, China
| | - Yuanxing Gu
- Zhejiang University Institute of Preventive Veterinary Medicine, and Zhejiang Provincial Key Laboratory of Preventive Veterinary Medicine Zhejiang, China
| | - Xiaoyan Zhang
- Zhejiang University Institute of Preventive Veterinary Medicine, and Zhejiang Provincial Key Laboratory of Preventive Veterinary Medicine Zhejiang, China
| | - Xiaoliang Li
- Zhejiang University Institute of Preventive Veterinary Medicine, and Zhejiang Provincial Key Laboratory of Preventive Veterinary Medicine Zhejiang, China
| | - Weihuan Fang
- Zhejiang University Institute of Preventive Veterinary Medicine, and Zhejiang Provincial Key Laboratory of Preventive Veterinary Medicine Zhejiang, China
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Yang YB, Chen JQ, Zhao YL, Bai JW, Ding WY, Zhou YH, Chen XY, Liu D, Li YH. Sub-MICs of Azithromycin Decrease Biofilm Formation of Streptococcus suis and Increase Capsular Polysaccharide Content of S. suis. Front Microbiol 2016; 7:1659. [PMID: 27812354 PMCID: PMC5072222 DOI: 10.3389/fmicb.2016.01659] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2016] [Accepted: 10/05/2016] [Indexed: 01/13/2023] Open
Abstract
Streptococcus suis (S. suis) caused serious disease symptoms in humans and pigs. S. suis is able to form thick biofilms and this increases the difficulty of treatment. After growth with 1/2 minimal inhibitory concentration (MIC) of azithromycin, 1/4 MIC of azithromycin, or 1/8 MIC of azithromycin, biofilm formation of S. suis dose-dependently decreased in the present study. Furthermore, scanning electron microscopy analysis revealed the obvious effect of azithromycin against biofilm formation of S. suis. Especially, at two different conditions (1/2 MIC of azithromycin non-treated cells and treated cells), we carried out comparative proteomic analyses of cells by using iTRAQ technology. Finally, the results revealed the existence of 19 proteins of varying amounts. Interestingly, several cell surface proteins (such as ATP-binding cassette superfamily ATP-binding cassette transporter (G7SD52), CpsR (K0FG35), Cps1/2H (G8DTL7), CPS16F (E9NQ13), putative uncharacterized protein (G7SER0), NADP-dependent glyceraldehyde-3-phosphate dehydrogenase (G5L259), putative uncharacterized protein (G7S2D6), amino acid permease (B0M0G6), and NsuB (G5L351)) were found to be implicated in biofilm formation. More importantly, we also found that azithromycin affected expression of the genes cps1/2H, cpsR and cps16F. Especially, after growth with 1/2 MIC of azithromycin and 1/4 MIC of azithromycin, the capsular polysaccharide content of S. suis was significantly higher.
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Affiliation(s)
- Yan-Bei Yang
- College of Veterinary Medicine, Northeast Agricultural University Harbin, China
| | - Jian-Qing Chen
- College of Veterinary Medicine, Northeast Agricultural University Harbin, China
| | - Yu-Lin Zhao
- College of Veterinary Medicine, Northeast Agricultural University Harbin, China
| | - Jing-Wen Bai
- College of Veterinary Medicine, Northeast Agricultural University Harbin, China
| | - Wen-Ya Ding
- College of Veterinary Medicine, Northeast Agricultural University Harbin, China
| | - Yong-Hui Zhou
- College of Veterinary Medicine, Northeast Agricultural University Harbin, China
| | - Xue-Ying Chen
- College of Veterinary Medicine, Northeast Agricultural University Harbin, China
| | - Di Liu
- Heilongjiang Academy of Agricultural Sciences Harbin, China
| | - Yan-Hua Li
- College of Veterinary Medicine, Northeast Agricultural University Harbin, China
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Segura M, Calzas C, Grenier D, Gottschalk M. Initial steps of the pathogenesis of the infection caused by Streptococcus suis: fighting against nonspecific defenses. FEBS Lett 2016; 590:3772-3799. [PMID: 27539145 DOI: 10.1002/1873-3468.12364] [Citation(s) in RCA: 87] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2016] [Revised: 08/11/2016] [Accepted: 08/16/2016] [Indexed: 12/16/2022]
Abstract
Interactions between a bacterial pathogen and its potentially susceptible host are initiated with the colonization step. During respiratory/oral infection, the pathogens must compete with the normal microflora, resist defense mechanisms of the local mucosal immunity, and finally reach, adhere, and breach the mucosal epithelial cell barrier in order to induce invasive disease. This is the case during infection by the swine and zoonotic pathogen Streptococcus suis, which is able to counteract mucosal barriers to induce severe meningitis and sepsis in swine and in humans. The initial steps of the pathogenesis of S. suis infection has been a neglected area of research, overshadowed by studies on the systemic and central nervous phases of the disease. In this Review article, we provide for the first time, an exclusive focus on S. suis colonization and the potential mechanisms involved in S. suis establishment at the mucosa, as well as the mechanisms regulating mucosal barrier breakdown. The role of mucosal immunity is also addressed. Finally, we demystify the extensive list of putative adhesins and virulence factors reported to be involved in the initial steps of pathogenesis by S. suis.
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Affiliation(s)
- Mariela Segura
- Laboratory of Immunology, Faculty of Veterinary Medicine, University of Montreal, Saint-Hyacinthe, Quebec, Canada.,Swine and Poultry Infectious Diseases Research Centre (CRIPA), Faculty of Veterinary Medicine, University of Montreal, Saint-Hyacinthe, QC, Canada
| | - Cynthia Calzas
- Laboratory of Immunology, Faculty of Veterinary Medicine, University of Montreal, Saint-Hyacinthe, Quebec, Canada.,Swine and Poultry Infectious Diseases Research Centre (CRIPA), Faculty of Veterinary Medicine, University of Montreal, Saint-Hyacinthe, QC, Canada.,Laboratory of Streptococcus suis, Faculty of Veterinary Medicine, University of Montreal, Saint-Hyacinthe, Quebec, Canada
| | - Daniel Grenier
- Swine and Poultry Infectious Diseases Research Centre (CRIPA), Faculty of Veterinary Medicine, University of Montreal, Saint-Hyacinthe, QC, Canada.,Groupe de Recherche en Écologie Buccale (GREB), Faculté de Médecine Dentaire, Université Laval, Quebec City, Quebec, Canada
| | - Marcelo Gottschalk
- Swine and Poultry Infectious Diseases Research Centre (CRIPA), Faculty of Veterinary Medicine, University of Montreal, Saint-Hyacinthe, QC, Canada.,Laboratory of Streptococcus suis, Faculty of Veterinary Medicine, University of Montreal, Saint-Hyacinthe, Quebec, Canada
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36
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Tohya M, Watanabe T, Maruyama F, Arai S, Ota A, Athey TBT, Fittipaldi N, Nakagawa I, Sekizaki T. Comparative Genome Analyses of Streptococcus suis Isolates from Endocarditis Demonstrate Persistence of Dual Phenotypic Clones. PLoS One 2016; 11:e0159558. [PMID: 27433935 PMCID: PMC4951133 DOI: 10.1371/journal.pone.0159558] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2016] [Accepted: 07/04/2016] [Indexed: 11/19/2022] Open
Abstract
Many bacterial species coexist in the same niche as heterogeneous clones with different phenotypes; however, understanding of infectious diseases by polyphenotypic bacteria is still limited. In the present study, encapsulation in isolates of the porcine pathogen Streptococcus suis from persistent endocarditis lesions was examined. Coexistence of both encapsulated and unencapsulated S. suis isolates was found in 26 out of 59 endocarditis samples. The isolates were serotype 2, and belonged to two different sequence types (STs), ST1 and ST28. The genomes of each of the 26 pairs of encapsulated and unencapsulated isolates from the 26 samples were sequenced. The data showed that each pair of isolates had one or more unique nonsynonymous mutations in the cps gene, and the encapsulated and unencapsulated isolates from the same samples were closest to each other. Pairwise comparisons of the sequences of cps genes in 7 pairs of encapsulated and unencapsulated isolates identified insertion/deletions (indels) ranging from one to 104 bp in different cps genes of unencapsulated isolates. Capsule expression was restored in a subset of unencapsulated isolates by complementation in trans with cps expression vectors. Examination of gene content common to isolates indicated that mutation frequency was higher in ST28 pairs than in ST1 pairs. Genes within mobile genetic elements were mutation hot spots among ST28 isolates. Taken all together, our results demonstrate the coexistence of dual phenotype (encapsulated and unencapsulated) bacterial clones and suggest that the dual phenotypes arose independently in each farm by means of spontaneous mutations in cps genes.
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Affiliation(s)
- Mari Tohya
- Research Center for Food Safety, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Bunkyo-ku, Tokyo, Japan
| | - Takayasu Watanabe
- Research Center for Food Safety, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Bunkyo-ku, Tokyo, Japan
| | - Fumito Maruyama
- Department of Microbiology, Kyoto University Graduate School of Medicine, Kyoto, Kyoto, Japan
- * E-mail: (TS); (FM)
| | - Sakura Arai
- Research Center for Food Safety, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Bunkyo-ku, Tokyo, Japan
| | - Atsushi Ota
- Department of Microbiology, Kyoto University Graduate School of Medicine, Kyoto, Kyoto, Japan
| | | | - Nahuel Fittipaldi
- Public Health Ontario, Toronto, Ontario, Canada
- Department of Laboratory Medicine and Pathobiology, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada
| | - Ichiro Nakagawa
- Department of Microbiology, Kyoto University Graduate School of Medicine, Kyoto, Kyoto, Japan
| | - Tsutomu Sekizaki
- Research Center for Food Safety, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Bunkyo-ku, Tokyo, Japan
- * E-mail: (TS); (FM)
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37
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Xu B, Pei X, Su Y, Ma Z, Fan H. Capsule of Streptococcus equi subsp. zooepidemicus hampers the adherence and invasion of epithelial and endothelial cells and is attenuated during internalization. FEMS Microbiol Lett 2016; 363:fnw164. [PMID: 27388015 DOI: 10.1093/femsle/fnw164] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/23/2016] [Indexed: 11/12/2022] Open
Abstract
Direct interaction between pathogens and host cells often is a prerequisite for colonization, infection and dissemination. Regulated production of capsular polysaccharide (CPS), which is made of hyaluronic acid, is essential for the pathogenicity of Streptococcus equi subsp. Zooepidemicus (SEZ). Here, we constructed a CPS-deleted mutant and analyzed it along with the parental wild-type strain in attachment and invasion of mammalian epithelial and endothelial cell lines. The CPS-deleted mutant exhibited significant increase in adherence and invasion by several orders of magnitude compared with the wild-type strain through quantitative analysis and electron microscopy observation. After the wild-type strain was recovered from invaded cells, its morphology was analyzed by visual methods and scanning electron microscopy, which revealed that its capsule was almost completely absent. Capsule measurements showed a similar result in which CPS production was nearly attenuated to the same extent as in the CPS-deleted mutant. qPCR assays revealed a marked reduction in the transcriptional levels of the CPS biosynthesis genes, has operon. Moreover, the repression in capsular production was stable inheritance. Our findings indicate that SEZ is a facultative intracellular bacterium, capsule attenuation in SEZ contributes to attachment and invasion in interactions with host cells, and the active regulation of capsule breakdown is controlled by SEZ during internalization.
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Affiliation(s)
- Bin Xu
- College of Veterinary Medicine, Nanjing Agricultural University, Nanjing 210095, China
| | - Xiaomeng Pei
- College of Veterinary Medicine, Nanjing Agricultural University, Nanjing 210095, China
| | - Yiqi Su
- College of Veterinary Medicine, Nanjing Agricultural University, Nanjing 210095, China
| | - Zhe Ma
- College of Veterinary Medicine, Nanjing Agricultural University, Nanjing 210095, China Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou 225009, China
| | - Hongjie Fan
- College of Veterinary Medicine, Nanjing Agricultural University, Nanjing 210095, China Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou 225009, China
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Tenenbaum T, Asmat TM, Seitz M, Schroten H, Schwerk C. Biological activities of suilysin: role in Streptococcus suis pathogenesis. Future Microbiol 2016; 11:941-54. [PMID: 27357518 DOI: 10.2217/fmb-2016-0028] [Citation(s) in RCA: 56] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Streptococcus suis is an important swine and zoonotic pathogen equipped with several virulence factors. The pore-forming toxins are the most abundant bacterial toxins and classified as critical virulence (associated) factors of several pathogens. The role of suilysin (SLY), a pore-forming cholesterol-dependent cytolysin of S. suis, as a true virulence factor is under debate. Most of the bacterial toxins have been reported to modulate the host immune system to facilitate invasion and subsequent replication of bacteria within respective host cells. SLY has been demonstrated to play an important role in the pathogenesis of S. suis infection and inflammatory response in vitro and in vivo. This review highlights the contributions of SLY to the pathogenicity of S. suis. It will address its role during the development of S. suis meningitis in pigs, as well as humans, and discuss SLY as a potential vaccine candidate.
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Affiliation(s)
- Tobias Tenenbaum
- Pediatric Infectious Diseases, Department of Pediatrics, Medical Faculty Mannheim, Heidelberg University, Theodor-Kutzer-Ufer 1-3, Mannheim D-68167, Germany
| | - Tauseef M Asmat
- Center for Advanced Studies in Vaccinology and Biotechnology, Brewery Road, University of Balochistan, 87300 Quetta, Pakistan
| | - Maren Seitz
- Institute for Microbiology, University of Veterinary Medicine Hannover, Bischofsholer Damm 15, Hannover D-30173, Germany
| | - Horst Schroten
- Pediatric Infectious Diseases, Department of Pediatrics, Medical Faculty Mannheim, Heidelberg University, Theodor-Kutzer-Ufer 1-3, Mannheim D-68167, Germany
| | - Christian Schwerk
- Pediatric Infectious Diseases, Department of Pediatrics, Medical Faculty Mannheim, Heidelberg University, Theodor-Kutzer-Ufer 1-3, Mannheim D-68167, Germany
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Jiang X, Yang Y, Zhu L, Gu Y, Shen H, Shan Y, Li X, Wu J, Fang W. Live Streptococcus suis type 5 strain XS045 provides cross-protection against infection by strains of types 2 and 9. Vaccine 2016; 34:6529-6538. [PMID: 27349838 DOI: 10.1016/j.vaccine.2016.05.003] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2016] [Revised: 04/26/2016] [Accepted: 05/02/2016] [Indexed: 11/27/2022]
Abstract
Streptococcus suis is one of the common pathogens causing diseases in pigs and covers 35 serotypes with the type 2 strains being more pathogenic and zoonotic. Existing inactivated or subunit vaccines, in clinical use or under trial, could not provide cross protection against other serotypes. We identified a natural low-virulence S. suis type 5 strain XS045 as a live vaccine candidate because it is highly adhesive to the cultured HEp-2 cells, but with no apparent pathogenicity in mice and piglets. We further demonstrate that subcutaneous administration of the live XS045 strain to mice induced high antibody responses and was able to provide cross protection against challenges by a type 2 strain HA9801 (100% protection) and a type 9 strain JX13 (85% protection). Induction of high-titer antibodies with opsonizing activity as well as their cross-reactivity to surface proteins of the types 2 and 9 strains and anti-adhesion effect could be the mechanisms of cross protection. This is the first report that a live vaccine candidate S. suis type 5 strain could induce cross-protection against strains of types 2 and 9. This candidate strain is to be further examined for safety in pigs of different ages and breeds as well as for its protection against other serotypes or other strains of the type 2, a serotype of particular importance from public health concern.
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Affiliation(s)
- Xiaowu Jiang
- Zhejiang University, Institute of Preventive Veterinary Medicine, and Zhejiang Provincial Key Laboratory of Preventive Veterinary Medicine, 866 Yuhangtang Road, Hangzhou, Zhejiang 310058, China
| | - Yunkai Yang
- Zhejiang University, Institute of Preventive Veterinary Medicine, and Zhejiang Provincial Key Laboratory of Preventive Veterinary Medicine, 866 Yuhangtang Road, Hangzhou, Zhejiang 310058, China
| | - Lexin Zhu
- Zhejiang University, Institute of Preventive Veterinary Medicine, and Zhejiang Provincial Key Laboratory of Preventive Veterinary Medicine, 866 Yuhangtang Road, Hangzhou, Zhejiang 310058, China
| | - Yuanxing Gu
- Zhejiang University, Institute of Preventive Veterinary Medicine, and Zhejiang Provincial Key Laboratory of Preventive Veterinary Medicine, 866 Yuhangtang Road, Hangzhou, Zhejiang 310058, China
| | - Hongxia Shen
- Zhejiang University, Institute of Preventive Veterinary Medicine, and Zhejiang Provincial Key Laboratory of Preventive Veterinary Medicine, 866 Yuhangtang Road, Hangzhou, Zhejiang 310058, China
| | - Ying Shan
- Zhejiang University, Institute of Preventive Veterinary Medicine, and Zhejiang Provincial Key Laboratory of Preventive Veterinary Medicine, 866 Yuhangtang Road, Hangzhou, Zhejiang 310058, China
| | - Xiaoliang Li
- Zhejiang University, Institute of Preventive Veterinary Medicine, and Zhejiang Provincial Key Laboratory of Preventive Veterinary Medicine, 866 Yuhangtang Road, Hangzhou, Zhejiang 310058, China
| | - Jiusheng Wu
- Zhejiang University, Institute of Preventive Veterinary Medicine, and Zhejiang Provincial Key Laboratory of Preventive Veterinary Medicine, 866 Yuhangtang Road, Hangzhou, Zhejiang 310058, China
| | - Weihuan Fang
- Zhejiang University, Institute of Preventive Veterinary Medicine, and Zhejiang Provincial Key Laboratory of Preventive Veterinary Medicine, 866 Yuhangtang Road, Hangzhou, Zhejiang 310058, China.
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Seele J, Nau R, Prajeeth CK, Stangel M, Valentin-Weigand P, Seitz M. Astrocytes Enhance Streptococcus suis-Glial Cell Interaction in Primary Astrocyte-Microglial Cell Co-Cultures. Pathogens 2016; 5:pathogens5020043. [PMID: 27304968 PMCID: PMC4931394 DOI: 10.3390/pathogens5020043] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2016] [Revised: 05/28/2016] [Accepted: 06/07/2016] [Indexed: 01/09/2023] Open
Abstract
Streptococcus (S.) suis infections are the most common cause of meningitis in pigs. Moreover, S. suis is a zoonotic pathogen, which can lead to meningitis in humans, mainly in adults. We assume that glial cells may play a crucial role in host-pathogen interactions during S. suis infection of the central nervous system. Glial cells are considered to possess important functions during inflammation and injury of the brain in bacterial meningitis. In the present study, we established primary astrocyte-microglial cell co-cultures to investigate interactions of S. suis with glial cells. For this purpose, microglial cells and astrocytes were isolated from new-born mouse brains and characterized by flow cytometry, followed by the establishment of astrocyte and microglial cell mono-cultures as well as astrocyte-microglial cell co-cultures. In addition, we prepared microglial cell mono-cultures co-incubated with uninfected astrocyte mono-culture supernatants and astrocyte mono-cultures co-incubated with uninfected microglial cell mono-culture supernatants. After infection of the different cell cultures with S. suis, bacteria-cell association was mainly observed with microglial cells and most prominently with a non-encapsulated mutant of S. suis. A time-dependent induction of NO release was found only in the co-cultures and after co-incubation of microglial cells with uninfected supernatants of astrocyte mono-cultures mainly after infection with the capsular mutant. Only moderate cytotoxic effects were found in co-cultured glial cells after infection with S. suis. Taken together, astrocytes and astrocyte supernatants increased interaction of microglial cells with S. suis. Astrocyte-microglial cell co-cultures are suitable to study S. suis infections and bacteria-cell association as well as NO release by microglial cells was enhanced in the presence of astrocytes.
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Affiliation(s)
- Jana Seele
- Center for Infection Medicine, Institute for Microbiology, University of Veterinary Medicine Hannover, Bischofsholer Damm 15, Hannover 30173, Germany.
- Institute for Neuropathology, University Medical Center Göttingen, Robert-Koch-Straße 40, Göttingen 37099, Germany.
- Department of Geriatrics, Evangelisches Krankenhaus Göttingen-Weende, An der Lutter 24, Göttingen 37075, Germany.
| | - Roland Nau
- Institute for Neuropathology, University Medical Center Göttingen, Robert-Koch-Straße 40, Göttingen 37099, Germany.
- Department of Geriatrics, Evangelisches Krankenhaus Göttingen-Weende, An der Lutter 24, Göttingen 37075, Germany.
| | - Chittappen K Prajeeth
- Department of Neurology, Center for Systems Neuroscience (ZSN), Hannover Medical School, Carl-Neuberg-Straße 1, Hannover 30625, Germany.
| | - Martin Stangel
- Department of Neurology, Center for Systems Neuroscience (ZSN), Hannover Medical School, Carl-Neuberg-Straße 1, Hannover 30625, Germany.
| | - Peter Valentin-Weigand
- Center for Infection Medicine, Institute for Microbiology, University of Veterinary Medicine Hannover, Bischofsholer Damm 15, Hannover 30173, Germany.
| | - Maren Seitz
- Center for Infection Medicine, Institute for Microbiology, University of Veterinary Medicine Hannover, Bischofsholer Damm 15, Hannover 30173, Germany.
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Efficient suilysin-mediated invasion and apoptosis in porcine respiratory epithelial cells after streptococcal infection under air-liquid interface conditions. Sci Rep 2016; 6:26748. [PMID: 27229328 PMCID: PMC4882623 DOI: 10.1038/srep26748] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2015] [Accepted: 05/05/2016] [Indexed: 12/25/2022] Open
Abstract
Streptococci may colonize the epithelium in the airways and other entry sites. While local infection often remains asymptomatic, severe or even fatal diseases occur when streptococci become invasive and spread to different sites in the infected host. We have established porcine respiratory air-liquid interface cultures (ALI) from the porcine lung to analyze the interaction of streptococci with their primary target cells. As representative of the streptococcal family we chose Streptococcus suis (S. suis) that is not only a major swine respiratory pathogen but can also infect humans. Suilysin, a cholesterol-dependent cytolysin (CDC), is an important virulence factor. By comparing a S. suis wt strain with a suilysin-deficient mutant, we demonstrate that suilysin contributes to (i) adherence to airway cells (ii) loss of ciliated cells (iii) apoptosis, and (iv) invasion. Furthermore, we show that cytolytic activity of suilysin is crucial for these effects. A striking result of our analysis was the high efficiency of S. suis-induced apoptosis and invasion upon infection under ALI conditions. These properties have been reported to be less efficient when analyzed with immortalized cells. We hypothesize that soluble effectors such as suilysin are present at higher concentrations in cells kept at ALI conditions and thus more effective. These results should be relevant also for infection of the respiratory tract by other respiratory pathogens.
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Haas B, Grenier D. Impact of Sub-Inhibitory Concentrations of Amoxicillin on Streptococcus suis Capsule Gene Expression and Inflammatory Potential. Pathogens 2016; 5:pathogens5020037. [PMID: 27104570 PMCID: PMC4931388 DOI: 10.3390/pathogens5020037] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2016] [Revised: 04/11/2016] [Accepted: 04/13/2016] [Indexed: 11/16/2022] Open
Abstract
Streptococcus suis is an important swine pathogen and emerging zoonotic agent worldwide causing meningitis, endocarditis, arthritis and septicemia. Among the 29 serotypes identified to date, serotype 2 is mostly isolated from diseased pigs. Although several virulence mechanisms have been characterized in S. suis, the pathogenesis of S. suis infections remains only partially understood. This study focuses on the response of S. suis P1/7 to sub-inhibitory concentrations of amoxicillin. First, capsule expression was monitored by qRT-PCR when S. suis was cultivated in the presence of amoxicillin. Then, the pro-inflammatory potential of S. suis P1/7 culture supernatants or whole cells conditioned with amoxicillin was evaluated by monitoring the activation of the NF-κB pathway in monocytes and quantifying pro-inflammatory cytokines secreted by macrophages. It was found that amoxicillin decreased capsule expression in S. suis. Moreover, conditioning the bacterium with sub-inhibitory concentrations of amoxicillin caused an increased activation of the NF-κB pathway in monocytes following exposure to bacterial culture supernatants and to a lesser extent to whole bacterial cells. This was associated with an increased secretion of pro-inflammatory cytokines (CXCL8, IL-6, IL-1β) by macrophages. This study identified a new mechanism by which S. suis may increase its inflammatory potential in the presence of sub-inhibitory concentrations of amoxicillin, a cell wall-active antibiotic, thus challenging its use for preventive treatments or as growth factor.
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Affiliation(s)
- Bruno Haas
- Groupe de Recherche en Écologie Buccale (GREB), Faculté de Médecine Dentaire, Université Laval, Quebec City, QC G1V 0A6, Canada.
| | - Daniel Grenier
- Groupe de Recherche en Écologie Buccale (GREB), Faculté de Médecine Dentaire, Université Laval, Quebec City, QC G1V 0A6, Canada.
- Centre de Recherche en Infectiologie Porcine et Avicole (CRIPA), Fonds de Recherche du Québec-Nature et Technologies (FRQNT), Saint-Hyacinthe, QC J2S 2M2, Canada.
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43
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Xu B, Yang X, Zhang P, Ma Z, Lin H, Fan H. The arginine deiminase system facilitates environmental adaptability of Streptococcus equi ssp. zooepidemicus through pH adjustment. Res Microbiol 2016; 167:403-12. [PMID: 27068185 DOI: 10.1016/j.resmic.2016.03.005] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2015] [Revised: 03/29/2016] [Accepted: 03/29/2016] [Indexed: 10/22/2022]
Abstract
The arginine deiminase system (ADS) is a secondary metabolic system found in many different bacterial pathogens and it is often associated with virulence. Here, a systematic study of ADS functions in Streptococcus equi subsp. zooepidemicus (SEZ) was performed. Transcriptional levels of ADS operon genes were observed to be significantly increased when SEZ was grown under acidic conditions. We constructed arcA and arcD deletion mutants (SEZ ΔarcA and SEZ ΔarcD, respectively) and found that SEZ ΔarcA was unable to metabolize arginine and synthesize ammonia; however, arcD deletion resulted in an initial decrease in arginine consumption and ammonia production, followed by recovery to the levels of wild-type SEZ after 24 h of cultivation. Cell extracts of SEZ ΔarcA showed no arginine deiminase (AD) activity, whereas no difference in AD activity between SEZ ΔarcD and wild-type SEZ was observed. SEZ survival tests demonstrated a significant decrease in survival for SEZ ΔarcA, when compared with wild-type SEZ, under acidic conditions and in epithelial cells. These findings indicate that ADS in SEZ contributes to environmental adaptability via ammonia synthesis to reduce pH stress.
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Affiliation(s)
- Bin Xu
- College of Veterinary Medicine, Nanjing Agricultural University, Nanjing 210095, China
| | - Xinyi Yang
- College of Veterinary Medicine, Nanjing Agricultural University, Nanjing 210095, China
| | - Ping Zhang
- College of Veterinary Medicine, Nanjing Agricultural University, Nanjing 210095, China
| | - Zhe Ma
- College of Veterinary Medicine, Nanjing Agricultural University, Nanjing 210095, China; Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou 225009, China
| | - Huixing Lin
- College of Veterinary Medicine, Nanjing Agricultural University, Nanjing 210095, China
| | - Hongjie Fan
- College of Veterinary Medicine, Nanjing Agricultural University, Nanjing 210095, China; Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou 225009, China.
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Zhang Y, Ding D, Liu M, Yang X, Zong B, Wang X, Chen H, Bei W, Tan C. Effect of the glycosyltransferases on the capsular polysaccharide synthesis of Streptococcus suis serotype 2. Microbiol Res 2016; 185:45-54. [PMID: 26946377 DOI: 10.1016/j.micres.2016.02.002] [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: 08/20/2015] [Revised: 01/04/2016] [Accepted: 02/03/2016] [Indexed: 02/03/2023]
Abstract
Streptococcus suis serotype 2 (S. suis 2) is a serious zoonotic pathogen causing septicemia and meningitis in piglets and humans. The capsular polysaccharide (CPS) is an essential virulence factor for S. suis 2 to infect the host. The synthesis of CPS repeating units involves multiple glycosyltransferases. In this study, four genes (cps2E, cps2G, cps2J and cps2L) encoding different glycosyltransferases involved in CPS synthesis were researched in S. suis 2. Four deletion mutants (Δcps2E, Δcps2G, Δcps2J and Δcps2L) with their CPS incomplete and their sialic acid content significantly decreased were constructed in S. suis 2 SC19. All these four mutant strains showed enhanced adhesion to Hep-2 cells and increased sensitivity to phagocytosis. Flow cytometric analysis also revealed that these four mutants were more susceptible to the attack by the complement system. In a mouse model of infection, the mutant strains were rapidly cleared by the immune system, compared with the wild-type strain. In summary, this study characterized four genes (cps2E, cps2G, cps2J and cps2L) involved in CPS synthesis of S. suis 2 SC19 and it revealed that these genes were all crucial for SC19 to invade and survive in the host.
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Affiliation(s)
- Yanyan Zhang
- State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan 430070, Hubei, China; The Cooperative Innovation Center for Sustainable Pig Production, Huazhong Agricultural University, Wuhan 430070, Hubei, China; Key Laboratory of Development of Veterinary Diagnostic Products of Ministry of Agriculture, Huazhong Agricultural University, Wuhan 430070, Hubei, China
| | - Dandan Ding
- State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan 430070, Hubei, China; The Cooperative Innovation Center for Sustainable Pig Production, Huazhong Agricultural University, Wuhan 430070, Hubei, China; Key Laboratory of Development of Veterinary Diagnostic Products of Ministry of Agriculture, Huazhong Agricultural University, Wuhan 430070, Hubei, China
| | - Manli Liu
- Center of Bio-Pesticide Engineering Research, Hubei Academy of Agricultural Science, Wuhan 430064, Hubei, China
| | - Xiaopei Yang
- State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan 430070, Hubei, China; The Cooperative Innovation Center for Sustainable Pig Production, Huazhong Agricultural University, Wuhan 430070, Hubei, China; Key Laboratory of Development of Veterinary Diagnostic Products of Ministry of Agriculture, Huazhong Agricultural University, Wuhan 430070, Hubei, China
| | - Bingbing Zong
- State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan 430070, Hubei, China; The Cooperative Innovation Center for Sustainable Pig Production, Huazhong Agricultural University, Wuhan 430070, Hubei, China; Key Laboratory of Development of Veterinary Diagnostic Products of Ministry of Agriculture, Huazhong Agricultural University, Wuhan 430070, Hubei, China
| | - Xiangru Wang
- State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan 430070, Hubei, China; The Cooperative Innovation Center for Sustainable Pig Production, Huazhong Agricultural University, Wuhan 430070, Hubei, China; Key Laboratory of Development of Veterinary Diagnostic Products of Ministry of Agriculture, Huazhong Agricultural University, Wuhan 430070, Hubei, China
| | - Huanchun Chen
- State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan 430070, Hubei, China; The Cooperative Innovation Center for Sustainable Pig Production, Huazhong Agricultural University, Wuhan 430070, Hubei, China; Key Laboratory of Development of Veterinary Diagnostic Products of Ministry of Agriculture, Huazhong Agricultural University, Wuhan 430070, Hubei, China
| | - Weicheng Bei
- State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan 430070, Hubei, China; The Cooperative Innovation Center for Sustainable Pig Production, Huazhong Agricultural University, Wuhan 430070, Hubei, China; Key Laboratory of Development of Veterinary Diagnostic Products of Ministry of Agriculture, Huazhong Agricultural University, Wuhan 430070, Hubei, China
| | - Chen Tan
- State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan 430070, Hubei, China; The Cooperative Innovation Center for Sustainable Pig Production, Huazhong Agricultural University, Wuhan 430070, Hubei, China; Key Laboratory of Development of Veterinary Diagnostic Products of Ministry of Agriculture, Huazhong Agricultural University, Wuhan 430070, Hubei, China.
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Doran KS, Fulde M, Gratz N, Kim BJ, Nau R, Prasadarao N, Schubert-Unkmeir A, Tuomanen EI, Valentin-Weigand P. Host-pathogen interactions in bacterial meningitis. Acta Neuropathol 2016; 131:185-209. [PMID: 26744349 PMCID: PMC4713723 DOI: 10.1007/s00401-015-1531-z] [Citation(s) in RCA: 112] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2015] [Revised: 12/21/2015] [Accepted: 12/22/2015] [Indexed: 12/26/2022]
Abstract
Bacterial meningitis is a devastating disease occurring worldwide with up to half of the survivors left with permanent neurological sequelae. Due to intrinsic properties of the meningeal pathogens and the host responses they induce, infection can cause relatively specific lesions and clinical syndromes that result from interference with the function of the affected nervous system tissue. Pathogenesis is based on complex host–pathogen interactions, some of which are specific for certain bacteria, whereas others are shared among different pathogens. In this review, we summarize the recent progress made in understanding the molecular and cellular events involved in these interactions. We focus on selected major pathogens, Streptococcus pneumonia, S. agalactiae (Group B Streptococcus), Neisseria meningitidis, and Escherichia coli K1, and also include a neglected zoonotic pathogen, Streptococcus suis. These neuroinvasive pathogens represent common themes of host–pathogen interactions, such as colonization and invasion of mucosal barriers, survival in the blood stream, entry into the central nervous system by translocation of the blood–brain and blood–cerebrospinal fluid barrier, and induction of meningeal inflammation, affecting pia mater, the arachnoid and subarachnoid spaces.
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Auger JP, Christodoulides M, Segura M, Xu J, Gottschalk M. Interactions of Streptococcus suis serotype 2 with human meningeal cells and astrocytes. BMC Res Notes 2015; 8:607. [PMID: 26502903 PMCID: PMC4624383 DOI: 10.1186/s13104-015-1581-2] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2015] [Accepted: 10/14/2015] [Indexed: 12/29/2022] Open
Abstract
BACKGROUND Streptococcus suis serotype 2 is an important porcine pathogen and emerging zoonotic agent responsible for meningitis, of which different sequence types predominate worldwide. Though bacterial meningitis is defined as an exacerbated inflammation of the meninges, the underlying astrocytes of the glia limitans superficialis may also be implicated. However, the interactions between this pathogen and human meningeal cells or astrocytes remain unknown. Furthermore, the roles of well-described virulence factors (capsular polysaccharide, suilysin and cell wall modifications) in these interactions have yet to be studied. Consequently, the interactions between S. suis serotype 2 and human meningeal cells or astrocytes were evaluated for the first time in order to better understand their involvement during meningitis in humans. RESULTS Streptococcus suis serotype 2 adhered to human meningeal cells and astrocytes; invasion of meningeal cells was rare however, whereas invasion of astrocytes was generally more frequent. Regardless of the interaction or cell type, differences were not observed between sequence types. Though the capsular polysaccharide modulated the adhesion to and invasion of meningeal cells and astrocytes, the suilysin and cell wall modifications only influenced astrocyte invasion. Surprising, S. suis serotype 2 induced little or no inflammatory response from both cell types, but this absence of inflammatory response was probably not due to S. suis-induced cell death. CONCLUSIONS Though S. suis serotype 2 interacted with human meningeal cells and astrocytes, there was no correlation between sequence type and interaction. Consequently, the adhesion to and invasion of human meningeal cells and astrocytes are strain-specific characteristics. As such, the meningeal cells of the leptomeninges and the astrocytes of the glia limitans superficialis may not be directly implicated in the inflammatory response observed during meningitis in humans.
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Affiliation(s)
- Jean-Philippe Auger
- Faculty of Veterinary Medicine, Research Group on Infectious Diseases of Swine (GREMIP) and Swine and Poultry Infectious Diseases Research Center (CRIPA), University of Montreal, 3200 Sicotte Street, Saint-Hyacinthe, QC, J2S 2M2, Canada.
| | - Myron Christodoulides
- Neisseria Research Group, Molecular Microbiology, Clinical and Experimental Sciences, University of Southampton Faculty of Medicine, Southampton, UK.
| | - Mariela Segura
- Faculty of Veterinary Medicine, Research Group on Infectious Diseases of Swine (GREMIP) and Swine and Poultry Infectious Diseases Research Center (CRIPA), University of Montreal, 3200 Sicotte Street, Saint-Hyacinthe, QC, J2S 2M2, Canada.
| | - Jianguo Xu
- Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, National Institute for Communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing, China.
| | - Marcelo Gottschalk
- Faculty of Veterinary Medicine, Research Group on Infectious Diseases of Swine (GREMIP) and Swine and Poultry Infectious Diseases Research Center (CRIPA), University of Montreal, 3200 Sicotte Street, Saint-Hyacinthe, QC, J2S 2M2, Canada.
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Sager M, Benten WPM, Engelhardt E, Gougoula C, Benga L. Characterization of Biofilm Formation in [Pasteurella] pneumotropica and [Actinobacillus] muris Isolates of Mouse Origin. PLoS One 2015; 10:e0138778. [PMID: 26430880 PMCID: PMC4592018 DOI: 10.1371/journal.pone.0138778] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2015] [Accepted: 09/03/2015] [Indexed: 12/24/2022] Open
Abstract
[Pasteurella] pneumotropica biotypes Jawetz and Heyl and [Actinobacillus] muris are the most prevalent Pasteurellaceae species isolated from laboratory mouse. However, mechanisms contributing to their high prevalence such as the ability to form biofilms have not been studied yet. In the present investigation we analyze if these bacterial species can produce biofilms in vitro and investigate whether proteins, extracellular DNA and polysaccharides are involved in the biofilm formation and structure by inhibition and dispersal assays using proteinase K, DNase I and sodium periodate. Finally, the capacity of the biofilms to confer resistance to antibiotics is examined. We demonstrate that both [P.] pneumotropica biotypes but not [A.] muris are able to form robust biofilms in vitro, a phenotype which is widely spread among the field isolates. The biofilm inhibition and dispersal assays by proteinase and DNase lead to a strong inhibition in biofilm formation when added at the initiation of the biofilm formation and dispersed pre-formed [P.] pneumotropica biofilms, revealing thus that proteins and extracellular DNA are essential in biofilm formation and structure. Sodium periodate inhibited the bacterial growth when added at the beginning of the biofilm formation assay, making difficult the assessment of the role of β-1,6-linked polysaccharides in the biofilm formation, and had a biofilm stimulating effect when added on pre-established mature biofilms of [P.] pneumotropica biotype Heyl and a majority of [P.] pneumotropica biotype Jawetz strains, suggesting that the presence of β-1,6-linked polysaccharides on the bacterial surface might attenuate the biofilm production. Conversely, no effect or a decrease in the biofilm quantity was observed by biofilm dispersal using sodium periodate on further biotype Jawetz isolates, suggesting that polysaccharides might be incorporated in the biofilm structure. We additionally show that [P.] pneumotropica cells enclosed in biofilms were less sensitive to treatment with amoxicillin and enrofloxacin than planktonic bacteria. Taken together, these findings provide a first step in understanding of the biofilm mechanisms in [P.] pneumotropica, which might contribute to elucidation of colonization and pathogenesis mechanisms for these obligate inhabitants of the mouse mucosa.
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Affiliation(s)
- Martin Sager
- Central Animal Research Facility, Heinrich—Heine—University, University Hospital, Düsseldorf, Germany
| | - W. Peter M. Benten
- Central Animal Research Facility, Heinrich—Heine—University, University Hospital, Düsseldorf, Germany
| | - Eva Engelhardt
- Central Animal Research Facility, Heinrich—Heine—University, University Hospital, Düsseldorf, Germany
| | - Christina Gougoula
- Central Animal Research Facility, Heinrich—Heine—University, University Hospital, Düsseldorf, Germany
| | - Laurentiu Benga
- Central Animal Research Facility, Heinrich—Heine—University, University Hospital, Düsseldorf, Germany
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Hatrongjit R, Kerdsin A, Gottschalk M, Takeuchi D, Hamada S, Oishi K, Akeda Y. First human case report of sepsis due to infection with Streptococcus suis serotype 31 in Thailand. BMC Infect Dis 2015; 15:392. [PMID: 26420029 PMCID: PMC4588491 DOI: 10.1186/s12879-015-1136-0] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2015] [Accepted: 09/21/2015] [Indexed: 01/11/2023] Open
Abstract
Background Streptococcus suis is a zoonotic pathogen that causes invasive infections in humans and pigs. It has been reported that S. suis infection in humans is mostly caused by serotype 2. However, human cases caused by other serotypes have rarely been reported. This is the first report of a human case of infection with S. suis serotype 31 in Thailand. Case presentation A 55-year-old male alcohol misuser with liver cirrhosis was admitted with sepsis to a hospital in the Central Region of Thailand. He had consumed a homemade, raw pork product prior to the onset of illness. He was alive after treatment with ceftriaxone and no complication occurred. An isolate from blood culture at the hospital was suspected as viridans group Streptococcus. It was confirmed at a reference laboratory as S. suis serotype 31 by biochemical tests, 16S rDNA sequencing, and multiplex polymerase chain reaction for serotyping, but it was untypable by the co-agglutination test with antisera against recognized S. suis serotypes, suggesting loss of capsular material. The absence of a capsule was confirmed by transmission electron microscopy. The isolate was confirmed to be sequence type 221, with 13 putative virulence genes that are usually found in serotype 2 strains. Conclusion We should be aware of the emergence of S. suis infections caused by uncommon serotypes in patients with predisposing conditions. Laboratory capacity to identify S. suis in the hospital is needed in developing countries, which can contribute to enhanced surveillance, epidemiological control, and prevention strategies in the prevalent area. Electronic supplementary material The online version of this article (doi:10.1186/s12879-015-1136-0) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Rujirat Hatrongjit
- Faculty of Science and Engineering, Kasetsart University Chalermphrakiat Sakon Nakhon Province Campus, Muang, Sakon Nakhon Province, 47000, Thailand.
| | - Anusak Kerdsin
- National Institute of Health, Department of Medical Sciences, Ministry of Public Health, Tiwanon Road, Muang, Nonthaburi Province, 11000, Thailand. .,Present address: Faculty of Public Health, Kasetsart University Chalermphrakiat Sakon Nakhon Province Campus, Sakon Nakhon, Thailand.
| | | | - Dan Takeuchi
- Laboratory of Clinical Research on Infectious Diseases, International Research Center for Infectious Diseases, Research Institute for Microbial Diseases, Osaka University, 3-1 Yamadaoka, Suita, Osaka, 565-0871, Japan.
| | - Shigeyuki Hamada
- Thailand-Japan Research Collaboration Center on Emerging and Re-emerging Infections, Nonthaburi Province, Thailand.
| | - Kazunori Oishi
- Infectious Disease Surveillance Center, National Institute of Infectious Diseases, Shinjyuku, Tokyo, Japan.
| | - Yukihiro Akeda
- Laboratory of Clinical Research on Infectious Diseases, International Research Center for Infectious Diseases, Research Institute for Microbial Diseases, Osaka University, 3-1 Yamadaoka, Suita, Osaka, 565-0871, Japan.
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Wu NH, Meng F, Seitz M, Valentin-Weigand P, Herrler G. Sialic acid-dependent interactions between influenza viruses and Streptococcus suis affect the infection of porcine tracheal cells. J Gen Virol 2015; 96:2557-2568. [PMID: 26297001 DOI: 10.1099/jgv.0.000223] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Bacterial co-infections are a major complication in influenza-virus-induced disease in both humans and animals. Either of the pathogens may induce a host response that affects the infection by the other pathogen. A unique feature in the co-infection by swine influenza viruses (SIV) and Streptococcus suis serotype 2 is the direct interaction between the two pathogens. It is mediated by the haemagglutinin of SIV that recognizes the α2,6-linked sialic acid present in the capsular polysaccharide of Streptococcus suis. In the present study, this interaction was demonstrated for SIV of both H1N1 and H3N2 subtypes as well as for human influenza viruses that recognize α2,6-linked sialic acid. Binding of SIV to Streptococcus suis resulted in co-sedimentation of virus with bacteria during low-speed centrifugation. Viruses bound to bacteria retained infectivity but induced only tiny plaques compared with control virus. Infection of porcine tracheal cells by SIV facilitated adherence of Streptococcus suis, which was evident by co-staining of bacterial and viral antigen. Sialic-acid-dependent binding of Streptococcus suis was already detectable after incubation for 30 min. By contrast, bacterial co-infection had a negative effect on the replication of SIV as indicated by lower virus titres in the supernatant and a delay in the kinetics of virus release.
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Affiliation(s)
- Nai-Huei Wu
- Institute of Virology, University of Veterinary Medicine Hannover, Hannover, Germany
| | - Fandan Meng
- Institute of Virology, University of Veterinary Medicine Hannover, Hannover, Germany
| | - Maren Seitz
- Institute of Microbiology, University of Veterinary Medicine Hannover, Hannover, Germany
| | - Peter Valentin-Weigand
- Institute of Microbiology, University of Veterinary Medicine Hannover, Hannover, Germany
| | - Georg Herrler
- Institute of Virology, University of Veterinary Medicine Hannover, Hannover, Germany
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Dynamic Virus-Bacterium Interactions in a Porcine Precision-Cut Lung Slice Coinfection Model: Swine Influenza Virus Paves the Way for Streptococcus suis Infection in a Two-Step Process. Infect Immun 2015; 83:2806-15. [PMID: 25916988 DOI: 10.1128/iai.00171-15] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2015] [Accepted: 04/21/2015] [Indexed: 12/17/2022] Open
Abstract
Swine influenza virus (SIV) and Streptococcus suis are common pathogens of the respiratory tract in pigs, with both being associated with pneumonia. The interactions of both pathogens and their contribution to copathogenesis are only poorly understood. In the present study, we established a porcine precision-cut lung slice (PCLS) coinfection model and analyzed the effects of a primary SIV infection on secondary infection by S. suis at different time points. We found that SIV promoted adherence, colonization, and invasion of S. suis in a two-step process. First, in the initial stages, these effects were dependent on bacterial encapsulation, as shown by selective adherence of encapsulated, but not unencapsulated, S. suis to SIV-infected cells. Second, at a later stage of infection, SIV promoted S. suis adherence and invasion of deeper tissues by damaging ciliated epithelial cells. This effect was seen with a highly virulent SIV subtype H3N2 strain but not with a low-virulence subtype H1N1 strain, and it was independent of the bacterial capsule, since an unencapsulated S. suis mutant behaved in a way similar to that of the encapsulated wild-type strain. In conclusion, the PCLS coinfection model established here revealed novel insights into the dynamic interactions between SIV and S. suis during infection of the respiratory tract. It showed that at least two different mechanisms contribute to the beneficial effects of SIV for S. suis, including capsule-mediated bacterial attachment to SIV-infected cells and capsule-independent effects involving virus-mediated damage of ciliated epithelial cells.
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