1
|
Wu C, Zhao Z, Liu Y, Zhu X, Liu M, Luo P, Shi Y. Type III Secretion 1 Effector Gene Diversity Among Vibrio Isolates From Coastal Areas in China. Front Cell Infect Microbiol 2020; 10:301. [PMID: 32637366 PMCID: PMC7318850 DOI: 10.3389/fcimb.2020.00301] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2020] [Accepted: 05/20/2020] [Indexed: 01/22/2023] Open
Abstract
Vibrios, which include more than 120 valid species, are an abundant and diverse group of bacteria in marine and estuarine environments. Some of these bacteria have been recognized as pathogens of both marine animals and humans, and therefore, their virulence mechanisms have attracted increasing attention. The type III secretion system (T3SS) is an important virulence determinant in many gram-negative bacteria, in which this system directly translocates variable effectors into the host cytosol for the manipulation of the cellular responses. In this study, the distribution of the T3SS gene cluster was first examined in 110 Vibrio strains of 26 different species, including 98 strains isolated from coastal areas in China. Several T3SS1 genes, but not T3SS2 genes (T3SS2α and T3SS2β), were universally detected in all the strains of four species, Vibrio parahaemolyticus, Vibrio alginolyticus, Vibrio harveyi, and Vibrio campbellii. The effector coding regions within the T3SS1 gene clusters from the T3SS1-positive strains were further analyzed, revealing that variations in the effectors of Vibrio T3SS1 were observed among the four Vibrio species, even between different strains in V. harveyi, according to their genetic organization. Importantly, Afp17, a potential novel effector that may exert a similar function as the known effector VopS in T3SS1-induced cell death, based on cytotoxicity assay results, was found in the effector coding region of the T3SS1 in some V. harveyi and V. campbellii strains. Finally, it was revealed that differences in T3SS1-mediated cytotoxicity were dependent not only on the variations in the effectors of Vibrio T3SS1 but also on the initial adhesion ability to host cells, which is another prerequisite condition. Altogether, our results contribute to the clarification of the diversity of T3SS1 effectors and a better understanding of the differences in cytotoxicity among Vibrio species.
Collapse
Affiliation(s)
- Chao Wu
- Department of Marine Biology, College of Oceanography, Hohai University, Nanjing, China
| | - Zhe Zhao
- Department of Marine Biology, College of Oceanography, Hohai University, Nanjing, China
| | - Yupeng Liu
- Department of Marine Biology, College of Oceanography, Hohai University, Nanjing, China
| | - Xinyuan Zhu
- Department of Marine Biology, College of Oceanography, Hohai University, Nanjing, China
| | - Min Liu
- Department of Marine Biology, College of Oceanography, Hohai University, Nanjing, China
| | - Peng Luo
- Key Laboratory of Marine Bio-Resources Sustainable Utilization, Key Laboratory of Applied Marine Biology of Guangdong Province, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, China
| | - Yan Shi
- Department of Marine Biology, College of Oceanography, Hohai University, Nanjing, China
| |
Collapse
|
2
|
Sinha-Ray S, Alam MT, Bag S, Morris JG, Ali A. Conversion of a recA-Mediated Non-toxigenic Vibrio cholerae O1 Strain to a Toxigenic Strain Using Chitin-Induced Transformation. Front Microbiol 2019; 10:2562. [PMID: 31787954 PMCID: PMC6854035 DOI: 10.3389/fmicb.2019.02562] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2019] [Accepted: 10/23/2019] [Indexed: 01/08/2023] Open
Abstract
Toxigenic Vibrio cholerae strains, including strains in serogroups O1 and O139 associated with the clinical disease cholera, are ubiquitous in aquatic reservoirs, including fresh, estuarine, and marine environments. Humans acquire cholera by consuming water and/or food contaminated with the microorganism. The genome of toxigenic V. cholerae harbors a cholera-toxin producing prophage (CT-prophage) encoding genes that promote expression of cholera toxin. The CT-prophage in V. cholerae is flanked by two satellite prophages, RS1 and TLC. Using cell surface appendages (TCP and/or MSHA pili), V. cholerae can sequentially acquire TLC, RS1, and CTX phages by transduction; the genome of each of these phages ultimately integrates into V. cholerae's genome in a site-specific manner. Here, we showed that a non-toxigenic V. cholerae O1 biotype El Tor strain, lacking the entire RS1-CTX-TLC prophage complex (designated as RCT: R for RS1, C for CTX and T for TLC prophage, respectively), was able to acquire RCT from donor genomic DNA (gDNA) of a wild-type V. cholerae strain (E7946) via chitin-induced transformation. Moreover, we demonstrated that a chitin-induced transformant (designated as AAS111) harboring RCT was capable of producing cholera toxin. We also showed that recA, rather than xerC and xerD recombinases, promoted the acquisition of RCT from donor gDNA by the recipient non-toxigenic V. cholerae strain. Our data document the existence of an alternative pathway by which a non-toxigenic V. cholerae O1 strain can transform to a toxigenic strain by using chitin induction. As chitin is an abundant natural carbon source in aquatic reservoirs where V. cholerae is present, chitin-induced transformation may be an important driver in the emergence of new toxigenic V. cholerae strains.
Collapse
Affiliation(s)
- Shrestha Sinha-Ray
- Emerging Pathogens Institute, University of Florida, Gainesville, FL, United States.,Department of Microbiology and Cell Science, College of Agricultural and Life Sciences, University of Florida, Gainesville, FL, United States
| | - Meer T Alam
- Emerging Pathogens Institute, University of Florida, Gainesville, FL, United States.,Department of Environmental and Global Health, College of Public Health and Health Professions, University of Florida, Gainesville, FL, United States
| | - Satyabrata Bag
- Emerging Pathogens Institute, University of Florida, Gainesville, FL, United States.,Department of Environmental and Global Health, College of Public Health and Health Professions, University of Florida, Gainesville, FL, United States
| | - J Glenn Morris
- Emerging Pathogens Institute, University of Florida, Gainesville, FL, United States.,Department of Medicine, School of Medicine, University of Florida, Gainesville, FL, United States
| | - Afsar Ali
- Emerging Pathogens Institute, University of Florida, Gainesville, FL, United States.,Department of Environmental and Global Health, College of Public Health and Health Professions, University of Florida, Gainesville, FL, United States
| |
Collapse
|
3
|
Affiliation(s)
- Carlos R Osorio
- a Departamento de Microbioloxía e Parasitoloxía , Instituto de Acuicultura, Universidade de Santiago de Compostela , Santiago de Compostela , Spain
| |
Collapse
|