1
|
First Record of the Rare Species Aeromonas lusitana from Rainbow Trout (Oncorhynchus mykiss, Walbaum): Comparative Analysis with the Existing Strains. Pathogens 2022; 11:pathogens11111299. [DOI: 10.3390/pathogens11111299] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2022] [Revised: 10/27/2022] [Accepted: 10/31/2022] [Indexed: 11/09/2022] Open
Abstract
The species Aeromonas lusitana was first described in 2016 with five strains recovered from untreated water and vegetables from Portugal. Since then, no further records exist of this species. During a surveillance study on the presence of Aeromonas in fish farms in Mexico, a new strain (ESV-351) of the mentioned species isolated from a rainbow trout was recovered. It was identified because it clustered phylogenetically with the type strain of A. lusitana based on the analysis of the rpoD gene sequences. In the present study, phenotypic characteristics, antimicrobial resistance profiles, and the presence of putative virulence genes of this novel strain (ESV-351) were determined in parallel to the five isolates from the original species description. Phenotypic differential characteristics exhibited by A. lusitana ESV-351 depicted an evident similarity to the characteristics exhibited by the other evaluated strains. However, the novel strain was positive for the production of indole using conventional methods, while the rest of the strains, including the type strain, were negative for its production. Furthermore, intermediate resistance to ampicillin, amoxicillin-clavulanic acid and cephalothin was detected in both the novel and the type strain. Five different virulence-related genes were detected in the novel strain and in the previously described strains, with the type strain exhibiting the highest number of virulence-related genes. In addition to this, the genome of the novel strain (ESV-351) was sequenced and compared with the genomes from the type strain (A. lusitana CECT 7828T) and other Aeromonas spp. The genomic analysis defined Aeromonas tecta as the closest species to A. lusitana with a highly similar number of predicted proteins. The genomic size, the number of protein-encoding genes and the number of different tRNAs, among other characteristics, make it possible to propose that the ESV-351 strain could potentially have the capacity to adapt to different environments. Genome comparison of the ESV-351 strain with the type strain revealed that both possess a similar sequence of the citrate synthase gene. In addition to this finding, the chromosomal region containing the citrate synthase locus of the novel strain exhibits some similarity to the chromosomal region in the genome of the A. hydrophila type strain and other known human pathogens, such as Vibrio cholerae. This could suggest a possible virulence role for the citrate synthase gene in A. lusitana (ESV-351).
Collapse
|
2
|
Samayanpaulraj V, Sivaramapillai M, Palani SN, Govindaraj K, Velu V, Ramesh U. Identification and characterization of virulent Aeromonas hydrophila Ah17 from infected Channa striata in river Cauvery and in vitro evaluation of shrimp chitosan. Food Sci Nutr 2020; 8:1272-1283. [PMID: 32148833 PMCID: PMC7020301 DOI: 10.1002/fsn3.1416] [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] [Received: 05/30/2019] [Revised: 12/26/2019] [Accepted: 12/27/2019] [Indexed: 11/06/2022] Open
Abstract
Aeromonas hydrophila, an inhabitant in the aquatic ecosystem is considered as an important foodborne bacterial zoonotic pathogen in aquaculture. The present study aimed to identify virulent A. hydrophila from naturally infected Channa striata in river Cauvery and in vitro evaluation of shrimp chitosan. Rimler Shotts (RS) and blood agar medium identified the presence of pathogenic Aeromonas sp. from the infected C. striata. A. hydrophila Ah17 was identified using 16S rRNA nucleotide sequence. Extracellular enzymes such as amylase, lipase, and protease were screened in A. hydrophila Ah17. Antibiotic susceptibility tests showed A. hydrophila Ah17 was highly resistant against β-lactam, glycopeptide, macrolides, phosphonic, fucidin, and oxazolidinone classes of antibiotics. Virulent genes such as hemolysin (aer and hly), heat-labile enterotoxin (act), cytotonic heat-stable enterotoxin (ast), elastase (ahyB), and lipase (lip) were identified. Growth and the viable cell population of virulent A. hydrophila Ah17 were significantly reduced in a dose-dependent manner against shrimp chitosan (CHS) from Penaeus indicus (P. indicus). Thus, the present study isolated virulent A. hydrophila Ah17 from the environmental source and characterized in vitro with shrimp chitosan.
Collapse
Affiliation(s)
- Vignesh Samayanpaulraj
- Department of Molecular BiologySchool of Biological SciencesMadurai Kamaraj UniversityIndia
| | | | - Sankara Naynar Palani
- Department of Molecular BiologySchool of Biological SciencesMadurai Kamaraj UniversityIndia
| | - Krishnaveni Govindaraj
- Department of Molecular BiologySchool of Biological SciencesMadurai Kamaraj UniversityIndia
| | - Vijay Velu
- Department of Molecular BiologySchool of Biological SciencesMadurai Kamaraj UniversityIndia
| | | |
Collapse
|
3
|
Gonçalves Pessoa RB, de Oliveira WF, Marques DSC, Dos Santos Correia MT, de Carvalho EVMM, Coelho LCBB. The genus Aeromonas: A general approach. Microb Pathog 2019; 130:81-94. [PMID: 30849490 DOI: 10.1016/j.micpath.2019.02.036] [Citation(s) in RCA: 92] [Impact Index Per Article: 18.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2018] [Revised: 02/27/2019] [Accepted: 02/28/2019] [Indexed: 02/07/2023]
Abstract
The genus Aeromonas comprises more than thirty Gram-negative bacterial species which mostly act as opportunistic microorganisms. These bacteria are distributed naturally in diverse aquatic ecosystems, where they are easily isolated from animals such as fish and crustaceans. A capacity for adaptation also makes Aeromonas able to colonize terrestrial environments and their inhabitants, so these microorganisms can be identified from different sources, such as soils, plants, fruits, vegetables, birds, reptiles, amphibians, among others. Infectious processes usually develop in immunocompromised humans; in fish and other marine animals this process occurs under conditions of stress. Such events are most often associated with incorrect practices in aquaculture. Aeromonas has element diverse ranges, denominated virulence factors, which promote adhesion, colonization and invasion into host cells. These virulence factors, such as membrane components, enzymes and toxins, for example, are differentially expressed among species, making some strains more virulent than others. Due to their diversity, no single virulence factor was considered determinant in the infectious process generated by these microorganisms. Unlike other genera, Aeromonas species are erroneously differentiated by conventional biochemical tests. Therefore, molecular assays are necessary for this purpose. Nevertheless, new means of identification have been considered in order to generate methods that, like molecular tests, can correctly identify these microorganisms. The main objectives of this review are to explain environmental and structural characteristics of the Aeromonas genus and to discuss virulence mechanisms that these bacteria use to infect aquatic organisms and humans, which are important aspects for aquaculture and public health, respectively. In addition, this review aims to clarify new tests for the precise identification of the species of Aeromonas, contributing to the exact and specific diagnosis of infections by these microorganisms and consequently the treatment.
Collapse
Affiliation(s)
- Rafael Bastos Gonçalves Pessoa
- Departamento de Bioquímica, Centro de Biociências, Universidade Federal de Pernambuco (UFPE), Av. Prof. Moraes Rego, s/n, Cidade Universitária, CEP: 50670-420, Recife, Pernambuco, Brazil
| | - Weslley Felix de Oliveira
- Departamento de Bioquímica, Centro de Biociências, Universidade Federal de Pernambuco (UFPE), Av. Prof. Moraes Rego, s/n, Cidade Universitária, CEP: 50670-420, Recife, Pernambuco, Brazil
| | - Diego Santa Clara Marques
- Departamento de Bioquímica, Centro de Biociências, Universidade Federal de Pernambuco (UFPE), Av. Prof. Moraes Rego, s/n, Cidade Universitária, CEP: 50670-420, Recife, Pernambuco, Brazil
| | - Maria Tereza Dos Santos Correia
- Departamento de Bioquímica, Centro de Biociências, Universidade Federal de Pernambuco (UFPE), Av. Prof. Moraes Rego, s/n, Cidade Universitária, CEP: 50670-420, Recife, Pernambuco, Brazil
| | - Elba Verônica Matoso Maciel de Carvalho
- Departamento de Bioquímica, Centro de Biociências, Universidade Federal de Pernambuco (UFPE), Av. Prof. Moraes Rego, s/n, Cidade Universitária, CEP: 50670-420, Recife, Pernambuco, Brazil
| | - Luana Cassandra Breitenbach Barroso Coelho
- Departamento de Bioquímica, Centro de Biociências, Universidade Federal de Pernambuco (UFPE), Av. Prof. Moraes Rego, s/n, Cidade Universitária, CEP: 50670-420, Recife, Pernambuco, Brazil.
| |
Collapse
|
4
|
FERNANDA SHANNI, ABINAWANTO ABINAWANTO, HELIANTI IS. Isolation of a Functional Gene Encoding Homologous Lysophospholipase from Indonesian Indigenous Bacillus halodurans CM1. MICROBIOLOGY INDONESIA 2019. [DOI: 10.5454/mi.13.1.2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
|
5
|
De Silva B, Hossain S, Dahanayake P, Heo GJ. Aeromonasspp. from marketed Yesso scallop (Patinopecten yessoensis): molecular characterization, phylogenetic analysis, virulence properties and antimicrobial susceptibility. J Appl Microbiol 2018; 126:288-299. [DOI: 10.1111/jam.14106] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2018] [Revised: 08/05/2018] [Accepted: 09/08/2018] [Indexed: 11/28/2022]
Affiliation(s)
- B.C.J. De Silva
- Veterinary Medical Center and College of Veterinary Medicine; Chungbuk National University; Cheongju Korea
| | - S. Hossain
- Veterinary Medical Center and College of Veterinary Medicine; Chungbuk National University; Cheongju Korea
| | - P.S. Dahanayake
- Veterinary Medical Center and College of Veterinary Medicine; Chungbuk National University; Cheongju Korea
| | - G.-J. Heo
- Veterinary Medical Center and College of Veterinary Medicine; Chungbuk National University; Cheongju Korea
| |
Collapse
|
6
|
Talagrand-Reboul E, Latif-Eugenín F, Beaz-Hidalgo R, Colston S, Figueras MJ, Graf J, Jumas-Bilak E, Lamy B. Genome-driven evaluation and redesign of PCR tools for improving the detection of virulence-associated genes in aeromonads. PLoS One 2018; 13:e0201428. [PMID: 30110345 PMCID: PMC6093642 DOI: 10.1371/journal.pone.0201428] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2018] [Accepted: 07/16/2018] [Indexed: 12/16/2022] Open
Abstract
Many virulence factors have been described for opportunistic pathogens within the genus Aeromonas. Polymerase Chain Reactions (PCRs) are commonly used in population studies of aeromonads to detect virulence-associated genes in order to better understand the epidemiology and emergence of Aeromonas from the environment to host, but their performances have never been thoroughly evaluated. We aimed to determine diagnostic sensitivity and specificity of PCR assays for the detection of virulence-associated genes in a collection of Aeromonas isolates representative for the genetic diversity in the genus. Thirty-nine Aeromonas strains belonging to 27 recognized species were screened by published PCR assays for virulence-associated genes (act, aerA, aexT, alt, ascFG, ascV, ast, lafA, lip, ser, stx1, stx2A). In parallel, homologues of the 12 putative virulence genes were searched from the genomes of the 39 strains. Of the 12 published PCR assays for virulence factors, the comparison of PCR results and genome analysis estimated diagnostic sensitivities ranging from 34% to 100% and diagnostic specificities ranged from 71% to 100% depending upon the gene. To improve the detection of virulence-associated genes in aeromonads, we have designed new primer pairs for aerA/act, ser, lafA, ascFG and ascV, which showed excellent diagnostic sensitivity and specificity. Altogether, the analysis of high quality genomic data, which are more and more easy to obtain, provides significant improvements in the genetic detection of virulence factors in bacterial strains.
Collapse
Affiliation(s)
- Emilie Talagrand-Reboul
- Équipe Pathogènes Hydriques Santé Environnements, UMR 5569 HSM, Université de Montpellier, Montpellier, France
- Laboratoire de Bactériologie, Hôpitaux universitaires de Strasbourg, Strasbourg, France
- * E-mail: (BL); (ETR)
| | - Fadua Latif-Eugenín
- Unidad de Microbiología, Departamento de Ciencias Médicas Básicas, Facultad de Medicina y Ciencias de la Salud, IISPV, Universidad Rovira i Virgili, Reus, Spain
| | - Roxana Beaz-Hidalgo
- Unidad de Microbiología, Departamento de Ciencias Médicas Básicas, Facultad de Medicina y Ciencias de la Salud, IISPV, Universidad Rovira i Virgili, Reus, Spain
| | - Sophie Colston
- Department of Molecular and Cell Biology, University of Connecticut, Storrs, Connecticut, United States of America
| | - Maria-Jose Figueras
- Unidad de Microbiología, Departamento de Ciencias Médicas Básicas, Facultad de Medicina y Ciencias de la Salud, IISPV, Universidad Rovira i Virgili, Reus, Spain
| | - Joerg Graf
- Department of Molecular and Cell Biology, University of Connecticut, Storrs, Connecticut, United States of America
| | - Estelle Jumas-Bilak
- Équipe Pathogènes Hydriques Santé Environnements, UMR 5569 HSM, Université de Montpellier, Montpellier, France
- Département d’Hygiène Hospitalière, CHRU de Montpellier, Montpellier, France
| | - Brigitte Lamy
- Équipe Pathogènes Hydriques Santé Environnements, UMR 5569 HSM, Université de Montpellier, Montpellier, France
- Département de Bactériologie, CHU de Nice, Nice, France
- * E-mail: (BL); (ETR)
| |
Collapse
|
7
|
Lakshmi SG, Jayanthi N, Saravanan M, Ratna MS. Safety assesment of Bacillus clausii UBBC07, a spore forming probiotic. Toxicol Rep 2017; 4:62-71. [PMID: 28959626 PMCID: PMC5615088 DOI: 10.1016/j.toxrep.2016.12.004] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2016] [Revised: 12/10/2016] [Accepted: 12/19/2016] [Indexed: 10/31/2022] Open
Abstract
Probiotics are vital bacteria that colonize the intestine and modify its microflora with benefits for the host. Very few members of the Bacillus group are recognized as safe for use and hence only a few strains are available as commercial preparations for application in humans and animals. Acute and subacute studies in rats were conducted to establish safety of Bacillus clausii (B. clausii) UBBC07. In the acute toxicity study, the oral LD50 for B. clausii UBBC07 was found to be >5000 mg/kg (630 billion cfu/kg) body weight. The NOAEL for B. clausii UBBC07 was found to be 1000 (126 billion cfu) mg/kg body weight/day by oral route in the subacute toxicity study. There were no significant differences between control and treated groups in any of the endpoints assessed using an OECD443 or OECD407 protocol. B. clausii UBBC07 was found to be resistant to three antibiotics -clindamycin, erythromycin and chloramphenicol. Analysis of the whole genome sequence of B. clausii UBBC07 revealed that the antibiotic resistance genes are present in chromosomal DNA which is intrinsic and not transferable. Toxin genes were also found to be absent. These results suggest consumption of B. clausii UBBC07 is safe for humans.
Collapse
Key Words
- ALP, alanine amino phosphate
- ALT, alanine amino transferase
- ALT, alanine aminotransferase
- AST, aspartate aminotransferase
- Acute toxicity
- Alb, albumin
- B. clausii UBBC07, Bacillus clausii UBBC07
- BUN, blood urea nitrogen
- Bacillus clausii UBBC07
- C, casts
- Creat, creatinine
- Cry, crystals
- EC, epithelial cells
- Ery, erythrocytes
- GC, granular casts
- Glob, globulin
- Glu, glucose
- Hct, hematocrit
- Hgb, hemoglobin
- Leu, leucocytes
- MCH, mean corpuscular hemoglobin
- MCHC, mean corpuscular hemoglobin concentration
- MCV, mean corpuscular volume
- NOAEL
- NOAEL, no observed adverse effect level
- Pro, protein
- RBC, red blood cell
- RET, reticulocyte
- SG, specific gravity
- Subacute toxicity
- T.Bil, total bilirubin
- T.chol, total cholesterol
- TP, total protein
- TPC, triple phosphate crystals
- Trig, triglycerides
- Vol, volume
- WBC, white blood cell
- Whole genome
Collapse
Affiliation(s)
- Suvarna G. Lakshmi
- Centre for Research and Development, Unique Biotech Limited, Hyderabad, India
| | - N. Jayanthi
- Centre for Research and Development, Unique Biotech Limited, Hyderabad, India
| | - M. Saravanan
- Vipragen Biosciences Pvt. Limited, Mysore, India
| | - M. Sudha Ratna
- Centre for Research and Development, Unique Biotech Limited, Hyderabad, India
| |
Collapse
|
8
|
Pang M, Xie X, Dong Y, Du H, Wang N, Lu C, Liu Y. Identification of novel virulence-related genes in Aeromonas hydrophila by screening transposon mutants in a Tetrahymena infection model. Vet Microbiol 2016; 199:36-46. [PMID: 28110783 DOI: 10.1016/j.vetmic.2016.12.021] [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: 08/16/2016] [Revised: 11/24/2016] [Accepted: 12/17/2016] [Indexed: 11/24/2022]
Abstract
Outbreaks of motile Aeromonad septicemia (MAS) in fish caused by sequence type (ST) 251 Aeromonas hydrophila have become a prominent problem for the aquaculture industry. The pathogenesis of A. hydrophila is very complicated, and some virulence factors remain to be identified. In this study, to identify novel virulence-related factors, ST251 A. hydrophila strain NJ-35 was used as the parental strain to construct a mutant library comprising 1030 mutant strains by transposon insertion mutagenesis. Subsequently, 33 virulence-attenuated transposon insertion mutants were identified using Tetrahymena and zebrafish as model hosts in sequence. Thermal asymmetric interlaced (Tail)-PCR and Southern blot analysis identified 21 single transposon insertion sites. Seven of the insertion sites are located in non-coding regions, whereas the other 14 insertion sites are located in genes, including aroA, rmlA, rtxA, chiA and plc. All insertion mutants exhibited attenuated virulence in Tetrahymena and zebrafish. Furthermore, the relationship of two genes, chiA and trkH, to virulence was confirmed by gene inactivation and subsequent restoration assays. This study provides new information about the genetic determinants of A. hydrophila pathogenicity and validates the Aeromonas-Tetrahymena co-culture model for high-throughput screening of A. hydrophila virulence factors.
Collapse
Affiliation(s)
- Maoda Pang
- College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, China; Key Lab of Food Quality and Safety of Jiangsu Province-State Key Laboratory Breeding Base, Institute of Food Safety, Jiangsu Academy of Agricultural Sciences, Nanjing, China
| | - Xing Xie
- College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, China
| | - Yuhao Dong
- College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, China
| | - Hechao Du
- College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, China
| | - Nannan Wang
- College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, China
| | - Chengping Lu
- College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, China
| | - Yongjie Liu
- College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, China.
| |
Collapse
|
9
|
Rasmussen-Ivey CR, Figueras MJ, McGarey D, Liles MR. Virulence Factors of Aeromonas hydrophila: In the Wake of Reclassification. Front Microbiol 2016; 7:1337. [PMID: 27610107 PMCID: PMC4997093 DOI: 10.3389/fmicb.2016.01337] [Citation(s) in RCA: 125] [Impact Index Per Article: 15.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2016] [Accepted: 08/12/2016] [Indexed: 12/19/2022] Open
Abstract
The ubiquitous "jack-of-all-trades," Aeromonas hydrophila, is a freshwater, Gram-negative bacterial pathogen under revision in regard to its phylogenetic and functional affiliation with other aeromonads. While virulence factors are expectedly diverse across A. hydrophila strains and closely related species, our mechanistic knowledge of the vast majority of these factors is based on the molecular characterization of the strains A. hydrophila AH-3 and SSU, which were reclassified as A. piscicola AH-3 in 2009 and A. dhakensis SSU in 2013. Individually, these reclassifications raise important questions involving the applicability of previous research on A. hydrophila virulence mechanisms; however, this issue is exacerbated by a lack of genomic data on other research strains. Collectively, these changes represent a fundamental gap in the literature on A. hydrophila and confirm the necessity of biochemical, molecular, and morphological techniques in the classification of research strains that are used as a foundation for future research. This review revisits what is known about virulence in A. hydrophila and the feasibility of using comparative genomics in light of this phylogenetic revision. Conflicting data between virulence factors, secretion systems, quorum sensing, and their effect on A. hydrophila pathogenicity appears to be an artifact of inappropriate taxonomic comparisons and/or be due to the fact that these properties are strain-specific. This review audits emerging data on dominant virulence factors that are present in both A. dhakensis and A. hydrophila in order to synthesize existing data with the aim of locating where future research is needed.
Collapse
Affiliation(s)
| | - Maria J Figueras
- Departamento de Ciencias Médicas Básicas, Facultad de Medicina y Ciencias de la Salud, Institut d'Investigació Sanitària Pere Virgili, Universidad Rovira i Virgili, Reus Spain
| | - Donald McGarey
- Department of Molecular and Cellular Biology, Kennesaw State University, Kennesaw, GA USA
| | - Mark R Liles
- Department of Biological Sciences, Auburn University, Auburn, AL USA
| |
Collapse
|
10
|
Králová S, Staňková E, Sedláček I. Classification of Aeromonas spp. isolated from water and clinical sources and distribution of virulence genes. Folia Microbiol (Praha) 2016; 61:513-521. [DOI: 10.1007/s12223-016-0464-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2015] [Accepted: 06/22/2016] [Indexed: 11/29/2022]
|
11
|
Abstract
Bacterial sphingomyelinases and phospholipases are a heterogeneous group of esterases which are usually surface associated or secreted by a wide variety of Gram-positive and Gram-negative bacteria. These enzymes hydrolyze sphingomyelin and glycerophospholipids, respectively, generating products identical to the ones produced by eukaryotic enzymes which play crucial roles in distinct physiological processes, including membrane dynamics, cellular signaling, migration, growth, and death. Several bacterial sphingomyelinases and phospholipases are essential for virulence of extracellular, facultative, or obligate intracellular pathogens, as these enzymes contribute to phagosomal escape or phagosomal maturation avoidance, favoring tissue colonization, infection establishment and progression, or immune response evasion. This work presents a classification proposal for bacterial sphingomyelinases and phospholipases that considers not only their enzymatic activities but also their structural aspects. An overview of the main physiopathological activities is provided for each enzyme type, as are examples in which inactivation of a sphingomyelinase- or a phospholipase-encoding gene impairs the virulence of a pathogen. The identification of sphingomyelinases and phospholipases important for bacterial pathogenesis and the development of inhibitors for these enzymes could generate candidate vaccines and therapeutic agents, which will diminish the impacts of the associated human and animal diseases.
Collapse
|
12
|
Igbinosa IH, Igbinosa EO, Okoh AI. Antibiogram characterization and putative virulence genes in Aeromonas species isolated from pig fecal samples. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2016; 23:12199-205. [PMID: 26971520 DOI: 10.1007/s11356-016-6421-y] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/09/2015] [Accepted: 03/03/2016] [Indexed: 05/12/2023]
Abstract
Aeromonas species are broadly distributed in nature and agricultural environments and have been isolated from feces, bedding, and drinking water of healthy pigs. We assessed the incidence, virulence properties, and antimicrobial resistance profile of Aeromonas spp., isolated from pig feces. Antibiogram was done using the disc diffusion methods, and polymerase chain reaction was used for the detection of putative virulence genes. Identification of isolates revealed three phenotypic species with percentage distribution as follows: Aeromonas hydrophila 23 (45.1 %), Aeromonas caviae 16 (31.4 %), and Aeromonas sobria 12 (23.5 %). All Aeromonas isolates in the study were absolutely susceptible to cefotaxime and resistant to penicillin. A. cavaie and A. sobria demonstrated absolute susceptibility against ciprofloxacin and streptomycin. Aeromonas species showed varied susceptibility to cephalothin as follows: A. hydrophila 78.3 %, A. cavaie 93.7 %, and A. sobria 91.7 %. The percentage distribution of virulence genes among Aeromonas isolates were as follows: Aerolysin (aer) 74.5 %, flagellin gene (fla) 68.6 %, cytotoxin (hly A) 43.1 %, lipase (lip) 39.2 %, enterotoxic activities (ast) 31.3 %, and cytotonic gene (alt) 13.7 %. Reports from this study shows that Aeromonas species isolated from pig fecal samples are multi-drug resistant and possess virulence potential which may result to possible risk of human or animal infection and likely contamination of food and water from this sources.
Collapse
Affiliation(s)
- Isoken H Igbinosa
- SA-MRC Microbial Water Quality Monitoring Centre, University of Fort Hare, Alice, 5700, South Africa.
- Department of Environmental Management and Toxicology, Faculty of Life Science University of Benin, Private Mail Bag 1154, Benin City, 300283, Nigeria.
| | - Etinosa O Igbinosa
- SA-MRC Microbial Water Quality Monitoring Centre, University of Fort Hare, Alice, 5700, South Africa
- Department of Microbiology, Faculty of life Sciences, University of Benin, Private Mail Bag 1154, Benin City, 300283, Nigeria
| | - Anthony I Okoh
- SA-MRC Microbial Water Quality Monitoring Centre, University of Fort Hare, Alice, 5700, South Africa
| |
Collapse
|
13
|
Zhu M, Wang XR, Li J, Li GY, Liu ZP, Mo ZL. Identification and virulence properties of Aeromonas veronii bv. sobria isolates causing an ulcerative syndrome of loach Misgurnus anguillicaudatus. JOURNAL OF FISH DISEASES 2016; 39:777-781. [PMID: 26525163 DOI: 10.1111/jfd.12413] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/03/2015] [Revised: 07/21/2015] [Accepted: 07/24/2015] [Indexed: 06/05/2023]
Affiliation(s)
- M Zhu
- College of Resources and Environmental Science, Nanjing Agricultural University, Nanjing, China
- College of Marine Science, Huaihai Institute of Technology, Lianyungang, China
| | - X R Wang
- Key Laboratory of Sustainable Development of Marine Fisheries, The Ministry of Agriculture, Qingdao, China
- College of Marine Life Sciences, Ocean University of China, Qingdao, China
| | - J Li
- Key Laboratory of Sustainable Development of Marine Fisheries, The Ministry of Agriculture, Qingdao, China
| | - G Y Li
- Key Laboratory of Sustainable Development of Marine Fisheries, The Ministry of Agriculture, Qingdao, China
| | - Z P Liu
- College of Resources and Environmental Science, Nanjing Agricultural University, Nanjing, China
| | - Z L Mo
- Key Laboratory of Sustainable Development of Marine Fisheries, The Ministry of Agriculture, Qingdao, China
| |
Collapse
|
14
|
Albarral V, Sanglas A, Palau M, Miñana-Galbis D, Fusté MC. Potential pathogenicity ofAeromonas hydrophilacomplex strains isolated from clinical, food, and environmental sources. Can J Microbiol 2016; 62:296-306. [DOI: 10.1139/cjm-2015-0466] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Aeromonas are autochthonous inhabitants of aquatic environments, including chlorinated and polluted waters, although they can also be isolated from a wide variety of environmental and clinical sources. They cause infections in vertebrates and invertebrates and are considered to be an emerging pathogen in humans, producing intestinal and extra-intestinal diseases. Most of the clinical isolates correspond to A. hydrophila, A. caviae, and A. veronii bv. Sobria, which are described as the causative agents of wound infections, septicaemia, and meningitis in immunocompromised people, and diarrhoea and dysenteric infections in the elderly and children. The pathogenic factors associated with Aeromonas are multifactorial and involve structural components, siderophores, quorum-sensing mechanisms, secretion systems, extracellular enzymes, and exotoxins. In this study, we analysed a representative number of clinical and environmental strains belonging to the A. hydrophila species complex to evaluate their potential pathogenicity. We thereby detected their enzymatic activities and antibiotic susceptibility pattern and the presence of virulence genes (aer, alt, ast, and ascV). The notably high prevalence of these virulence factors, even in environmental strains, indicated a potential pathogenic capacity. Additionally, we determined the adhesion capacity and cytopathic effects of this group of strains in Caco-2 cells. Most of the strains exhibited adherence and caused complete lysis.
Collapse
Affiliation(s)
- Vicenta Albarral
- Departament de Microbiologia i Parasitologia Sanitàries, Facultat de Farmàcia, Universitat de Barcelona, Avinguda Joan XXIII s/n, Barcelona 08028, Spain
| | - Ariadna Sanglas
- Departament de Microbiologia i Parasitologia Sanitàries, Facultat de Farmàcia, Universitat de Barcelona, Avinguda Joan XXIII s/n, Barcelona 08028, Spain
| | - Montserrat Palau
- Departament de Microbiologia i Parasitologia Sanitàries, Facultat de Farmàcia, Universitat de Barcelona, Avinguda Joan XXIII s/n, Barcelona 08028, Spain
| | - David Miñana-Galbis
- Departament de Microbiologia i Parasitologia Sanitàries, Facultat de Farmàcia, Universitat de Barcelona, Avinguda Joan XXIII s/n, Barcelona 08028, Spain
| | - M. Carmen Fusté
- Departament de Microbiologia i Parasitologia Sanitàries, Facultat de Farmàcia, Universitat de Barcelona, Avinguda Joan XXIII s/n, Barcelona 08028, Spain
- Institut de Recerca de la Biodiversitat, Universitat de Barcelona, Avinguda Diagonal 643, Barcelona 08028, Spain
| |
Collapse
|
15
|
Novel insights into the pathogenicity of epidemic Aeromonas hydrophila ST251 clones from comparative genomics. Sci Rep 2015; 5:9833. [PMID: 26014286 PMCID: PMC4444815 DOI: 10.1038/srep09833] [Citation(s) in RCA: 83] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2014] [Accepted: 03/13/2015] [Indexed: 12/16/2022] Open
Abstract
Outbreaks in fish of motile Aeromonad septicemia (MAS) caused by Aeromonas hydrophila have caused a great concern worldwide. Here, for the first time, we provide two complete genomes of epidemic A. hydrophila strains isolated in China. To gain an insight into the pathogenicity of epidemic A. hydrophila, we performed comparative genomic analyses of five epidemic strains belonging to sequence type (ST) 251, together with the environmental strain ATCC 7966T. We found that the known virulence factors, including a type III secretion system, a type VI secretion system and lateral flagella, are not required for the high virulence of the ST251 clonal group. Additionally, our work identifies three utilization pathways for myo-inositol, sialic acid and L-fucose providing clues regarding the factors that underlie the epidemic and virulent nature of ST251 A. hydrophila. Based on the geographical distribution and biological resources of the ST251 clonal group, we conclude that ST251 is a high-risk clonal group of A. hydrophila which may be responsible for the MAS outbreaks in China and the southeastern United States.
Collapse
|
16
|
Madec S, Pichereau V, Jacq A, Paillard M, Boisset C, Guérard F, Paillard C, Nicolas JL. Characterization of the secretomes of two vibrios pathogenic to mollusks. PLoS One 2014; 9:e113097. [PMID: 25401495 PMCID: PMC4234667 DOI: 10.1371/journal.pone.0113097] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2014] [Accepted: 10/19/2014] [Indexed: 02/05/2023] Open
Abstract
Vibrio tapetis causes the brown ring disease in the Japanese clam Ruditapes philippinarum while Vibrio aestuarianus is associated with massive oyster mortalities. As extracellular proteins are often associated with the virulence of pathogenic bacteria, we undertook a proteomic approach to characterize the secretomes of both vibrios. The extracellular proteins (ECPs) of both species were fractionated by SEC-FPLC and in vitro assays were performed to measure the effects of each fraction on hemocyte cellular parameters (phagocytosis and adhesion). Fractions showing a significant effect were subjected to SDS-PAGE, and proteins were identified by nano LC-MS/MS. 45 proteins were identified for V. aestuarianus and 87 for V. tapetis. Most of them belonged to outer membrane or were periplasmic, including porins or adhesins that were already described as virulence factors in other bacterial species. Others were transporter components, flagella proteins, or proteins of unknown function (14 and 15 respectively). Interestingly, for V. aestuarianus, we noted the secretion of 3 extracellular enzymes including the Vam metalloprotease and two other enzymes (one putative lipase and one protease). For V. tapetis, we identified five extracellular enymes, i.e. two different endochitinases, one protease, one lipase and an adhesin. A comparison of both secretomes also showed that only the putative extracellular lipase was common to both secretomes, underscoring the difference in pathogenicity mechanisms between these two species. Overall, these results characterize for the first time the secretomes of these two marine pathogenic vibrios and constitute a useful working basis to further analyze the contribution of specific proteins in the virulence mechanisms of these species.
Collapse
Affiliation(s)
- Stéphanie Madec
- Laboratoire Universitaire de Biodiversité et Ecologie Microbienne (EA3882), SFR48 ScInBios, Université de Bretagne Occidentale (UBO), UEB, ESIAB, Technopôle Brest Iroise, 29280, Plouzané, France
| | - Vianney Pichereau
- Laboratoire des Sciences de l’Environnement Marin, UMR 6539 UBO/CNRS/IRD/Ifremer, Université de Bretagne Occidentale (UBO), Institut Universitaire Européen de la Mer, Technopôle Brest Iroise, 29280, Plouzané, France
| | - Annick Jacq
- Institut de Génétique et de Microbiologie, UMR8621, CNRS-Université Paris-Sud, 91405, Orsay, France
| | - Mathieu Paillard
- Laboratoire des Sciences de l’Environnement Marin, UMR 6539 UBO/CNRS/IRD/Ifremer, Université de Bretagne Occidentale (UBO), Institut Universitaire Européen de la Mer, Technopôle Brest Iroise, 29280, Plouzané, France
| | - Claire Boisset
- Centre de Recherche sur les macromolécules végétales, CERMAV-CNRS, BP53, 38041 Grenoble, France
| | - Fabienne Guérard
- Laboratoire des Sciences de l’Environnement Marin, UMR 6539 UBO/CNRS/IRD/Ifremer, Université de Bretagne Occidentale (UBO), Institut Universitaire Européen de la Mer, Technopôle Brest Iroise, 29280, Plouzané, France
| | - Christine Paillard
- Laboratoire des Sciences de l’Environnement Marin, UMR 6539 UBO/CNRS/IRD/Ifremer, Université de Bretagne Occidentale (UBO), Institut Universitaire Européen de la Mer, Technopôle Brest Iroise, 29280, Plouzané, France
| | - Jean-Louis Nicolas
- Laboratoire des Sciences de l’Environnement Marin, UMR 6539 UBO/CNRS/IRD/Ifremer, Université de Bretagne Occidentale (UBO), Institut Universitaire Européen de la Mer, Technopôle Brest Iroise, 29280, Plouzané, France
| |
Collapse
|
17
|
Garcia-Galan C, dos Santos JC, Barbosa O, Torres R, Pereira EB, Corberan VC, Gonçalves LR, Fernandez-Lafuente R. Tuning of Lecitase features via solid-phase chemical modification: Effect of the immobilization protocol. Process Biochem 2014. [DOI: 10.1016/j.procbio.2014.01.028] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
|
18
|
Characterization of the Vibrio cholerae VolA surface-exposed lipoprotein lysophospholipase. J Bacteriol 2014; 196:1619-26. [PMID: 24532770 DOI: 10.1128/jb.01281-13] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Bacterial lipases play important roles in bacterial metabolism and environmental response. Our laboratory recently discovered that a novel lipoprotein lysophospholipase, VolA, localizes on the surface of the Gram-negative aquatic pathogen Vibrio cholerae. VolA functions to cleave exogenous lysophosphatidylcholine, freeing the fatty acid moiety for use by V. cholerae. This fatty acid is transported into the cell and can be used as a nutrient and, more importantly, as a way to alter the membrane architecture via incorporation into the phospholipid biosynthesis pathway. There are few examples of Gram-negative, surface-exposed lipoproteins, and VolA is unique, as it has a previously undercharacterized function in V. cholerae membrane remodeling. Herein, we report the biochemical characterization of VolA. We show that VolA is a canonical lipoprotein via mass spectrometry analysis and demonstrate the in vitro activity of VolA under a variety of conditions. Additionally, we show that VolA contains a conserved Gly-Xaa-Ser-Xaa-Gly motif typical of lipases. Interestingly, we report the observation of VolA homologs in other aquatic pathogens. An Aeromonas hydrophila VolA homolog complements a V. cholerae VolA mutant in growth on lysophosphatidylcholine as the sole carbon source and in enzymatic assays. These results support the idea that the lipase activity of surface-exposed VolA likely contributes to the success of V. cholerae, improving the overall adaptation and survival of the organism in different environments.
Collapse
|
19
|
Li L, Mou X, Nelson DR. Characterization of Plp, a phosphatidylcholine-specific phospholipase and hemolysin of Vibrio anguillarum. BMC Microbiol 2013; 13:271. [PMID: 24279474 PMCID: PMC4222444 DOI: 10.1186/1471-2180-13-271] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2013] [Accepted: 11/20/2013] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Vibrio anguillarum is the causative agent of vibriosis in fish. Several extracellular proteins secreted by V. anguillarum have been shown to contribute to virulence. While two hemolysin gene clusters, vah1-plp and rtxACHBDE, have been previously identified and described, the activities of the protein encoded by the plp gene were not known. Here we describe the biochemical activities of the plp-encoded protein and its role in pathogenesis. RESULTS The plp gene, one of the components in vah1 cluster, encodes a 416-amino-acid protein (Plp), which has homology to lipolytic enzymes containing the catalytic site amino acid signature SGNH. Hemolytic activity of the plp mutant increased 2-3-fold on sheep blood agar indicating that plp represses vah1; however, hemolytic activity of the plp mutant decreased by 2-3-fold on fish blood agar suggesting that Plp has different effects against erythrocytes from different species. His6-tagged recombinant Plp protein (rPlp) was over-expressed in E. coli. Purified and re-folded active rPlp exhibited phospholipase A2 activity against phosphatidylcholine and no activity against phosphatidylserine, phosphatidylethanolamine, or sphingomyelin. Characterization of rPlp revealed broad optimal activities at pH 5-9 and at temperatures of 30-64°C. Divalent cations and metal chelators did not affect activity of rPlp. We also demonstrated that Plp was secreted using thin layer chromatography and immunoblot analysis. Additionally, rPlp had strong hemolytic activity towards rainbow trout erythrocytes, but not to sheep erythrocytes suggesting that rPlp is optimized for lysis of phosphatidylcholine-rich fish erythrocytes. Further, only the loss of the plp gene had a significant effect on hemolytic activity of culture supernatant on fish erythrocytes, while the loss of rtxA and/or vah1 had little effect. However, V. anguillarum strains with mutations in plp or in plp and vah1 exhibited no significant reduction in virulence compared to the wild type strain when used to infect rainbow trout. CONCLUSION The plp gene of V. anguillarum encoding a phospholipase with A2 activity is specific for phosphatidylcholine and, therefore, able to lyse fish erythrocytes, but not sheep erythrocytes. Mutation of plp does not affect the virulence of V. anguillarum in rainbow trout.
Collapse
Affiliation(s)
- Ling Li
- Department of Cell and Molecular Biology, University of Rhode Island, 120 Flagg Rd,, Kingston, RI 02881, USA.
| | | | | |
Collapse
|
20
|
Aeromonas molluscorum Av27 is a potential tributyltin (TBT) bioremediator: phenotypic and genotypic characterization indicates its safe application. Antonie van Leeuwenhoek 2013; 104:385-96. [DOI: 10.1007/s10482-013-9961-x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/15/2013] [Accepted: 06/26/2013] [Indexed: 01/08/2023]
|
21
|
Beaz-Hidalgo R, Figueras MJ. Aeromonas spp. whole genomes and virulence factors implicated in fish disease. JOURNAL OF FISH DISEASES 2013; 36:371-388. [PMID: 23305319 DOI: 10.1111/jfd.12025] [Citation(s) in RCA: 156] [Impact Index Per Article: 14.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/14/2012] [Revised: 09/20/2012] [Accepted: 09/23/2012] [Indexed: 05/27/2023]
Abstract
It is widely recognized that Aeromonas infections produce septicaemia, and ulcerative and haemorrhagic diseases in fish, causing significant mortality in both wild and farmed freshwater and marine fish species that damage the economics of the aquaculture sector. The descriptions of the complete genomes of Aeromonas species have allowed the identification of an important number of virulence genes that affect the pathogenic potential of these bacteria. This review will focus on the most relevant information derived from the available Aeromonas genomes in relation to virulence and on the diverse virulence factors that actively participate in host adherence, colonization and infection, including structural components, extracellular factors, secretion systems, iron acquisition and quorum sensing mechanisms.
Collapse
Affiliation(s)
- R Beaz-Hidalgo
- Unitat de Microbiologia, Departament de Ciènces Médiques Bàsiques, Facultat de Medicina i Ciències de la Salut, IISPV, Universitat Rovira i Virgili, Reus, Spain
| | | |
Collapse
|
22
|
Tomás JM. The main Aeromonas pathogenic factors. ISRN MICROBIOLOGY 2012; 2012:256261. [PMID: 23724321 PMCID: PMC3658858 DOI: 10.5402/2012/256261] [Citation(s) in RCA: 184] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/02/2012] [Accepted: 07/19/2012] [Indexed: 12/27/2022]
Abstract
The members of the Aeromonas genus are ubiquitous, water-borne bacteria. They have been isolated from marine waters, rivers, lakes, swamps, sediments, chlorine water, water distribution systems, drinking water and residual waters; different types of food, such as meat, fish, seafood, vegetables, and processed foods. Aeromonas strains are predominantly pathogenic to poikilothermic animals, and the mesophilic strains are emerging as important pathogens in humans, causing a variety of extraintestinal and systemic infections as well as gastrointestinal infections. The most commonly described disease caused by Aeromonas is the gastroenteritis; however, no adequate animal model is available to reproduce this illness caused by Aeromonas. The main pathogenic factors associated with Aeromonas are: surface polysaccharides (capsule, lipopolysaccharide, and glucan), S-layers, iron-binding systems, exotoxins and extracellular enzymes, secretion systems, fimbriae and other nonfilamentous adhesins, motility and flagella.
Collapse
Affiliation(s)
- J M Tomás
- Departamento Microbiología, Universidad de Barcelona, Diagonal 643, 08071 Barcelona, Spain
| |
Collapse
|
23
|
Actin cross-linking domain of Aeromonas hydrophila repeat in toxin A (RtxA) induces host cell rounding and apoptosis. Gene 2012; 506:369-76. [PMID: 22814176 DOI: 10.1016/j.gene.2012.07.012] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2012] [Revised: 06/15/2012] [Accepted: 07/09/2012] [Indexed: 11/24/2022]
Abstract
The repeat in toxin (Rtx) of an environmental isolate ATCC 7966 of Aeromonas hydrophila consists of six genes (rtxACHBDE) organized in an operon similar to the gene organization found for the Rtx of the Vibrio species. The first gene in this operon (rtxA) encodes an exotoxin in vibrios, while other genes code for proteins needed for proper activation of RtxA and in secretion of this toxin from Vibrio cholerae. However, the RtxA of ATCC 7966, as well as from the clinical isolate SSU of A. hydrophila, was exclusively expressed and produced during co-infection of this pathogen with the host, e.g., HeLa cells, indicating that rtxA gene expression required host cell contact. Within the RtxA, an actin cross-linking domain (ACD) exists and to investigate the functionality of this domain, several truncated versions of ACD were generated to discern its minimal biological active region. Such genetically modified genes encoding ACD, which were truncated on either the NH(2) or the COOH terminal, as well as on both ends, were expressed from a bidirectional promoter of the pBI-enhanced green fluorescent protein (EGFP) vector in a HeLa-Tet-Off cell system. We demonstrated that only the full-length ACD of RtxA from A. hydrophila catalyzed the covalent cross-linking of the host cellular actin, whereas the ACD truncated on the NH(2), COOH or both ends did not exhibit such actin cross-linking characteristics. Further, we showed that the full-length ACD of A. hydrophila RtxA disrupted the actin cytoskeleton of HeLa cells, resulting in their rounding phenotype. Finally, our data provided evidence that the full-length ACD of RtxA induced host cell apoptosis. Our study is the first to report that A. hydrophila possesses a functional RtxA having an ACD that contributes to the host cell apoptosis, and hence could represent a potential virulence factor of this emerging human pathogen.
Collapse
|
24
|
Takahashi E, Ito H, Kobayashi H, Yamanaka H, Takeda Y, Balakrish Nair G, Arimoto S, Negishi T, Okamoto K. Production and properties of lipase of Aeromonas sobria. Microbiol Immunol 2012; 56:295-307. [PMID: 22376235 DOI: 10.1111/j.1348-0421.2012.00445.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Aeromonas have been isolated from a wide variety of aquatic environments. However the number of Aeromonas in sea water is extremely small compared to that in fresh water. In in vitro culture, Aeromonas can grow in mediums containing NaCl at a concentration of 3.0%, this concentration corresponding to that of sea water. It is unclear why the number of Aeromonas is low in sea water. Exoproteins of bacteria are thought to be important for bacterial growth and survival in the environment. Previously, the present authors have shown that mediums containing 3.0% NaCl suppress production of two proteases, serine protease and metalloprotease. In this experiment, other exoproteins whose production is influenced by the amount of NaCl in the medium were analyzed. A protein whose production is repressed in medium containing 3.0% NaCl was found and purified. Biological assay of the purified protein showed that it degrades tributyrin and hydrolyzes para-nitrophenyl-fatty acylesters. These results show that the protein is a lipase. Subsequently, the nucleotide sequence of the gene encoding the lipase was determined and the amount of mRNA of the lipase gene in the cells measured. It was found that transcription of the gene is not inhibited by NaCl in the medium. This result indicates that the lipase might be synthesized, but the folding process to become an active structure does not progress smoothly in a medium containing 3.0% NaCl.
Collapse
Affiliation(s)
- Eizo Takahashi
- Laboratory of Protein Function, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, 1-1-1 Tsushima-naka, Kitaku, Okayama, Japan.
| | | | | | | | | | | | | | | | | |
Collapse
|
25
|
Puthucheary SD, Puah SM, Chua KH. Molecular characterization of clinical isolates of Aeromonas species from Malaysia. PLoS One 2012; 7:e30205. [PMID: 22383958 PMCID: PMC3287994 DOI: 10.1371/journal.pone.0030205] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2011] [Accepted: 12/12/2011] [Indexed: 11/24/2022] Open
Abstract
Background Aeromonas species are common inhabitants of aquatic environments giving rise to infections in both fish and humans. Identification of aeromonads to the species level is problematic and complex due to their phenotypic and genotypic heterogeneity. Methodology/Principal Findings Aeromonas hydrophila or Aeromonas sp were genetically re-identified using a combination of previously published methods targeting GCAT, 16S rDNA and rpoD genes. Characterization based on the genus specific GCAT-PCR showed that 94 (96%) of the 98 strains belonged to the genus Aeromonas. Considering the patterns obtained for the 94 isolates with the 16S rDNA-RFLP identification method, 3 clusters were recognised, i.e. A. caviae (61%), A. hydrophila (17%) and an unknown group (22%) with atypical RFLP restriction patterns. However, the phylogenetic tree constructed with the obtained rpoD sequences showed that 47 strains (50%) clustered with the sequence of the type strain of A. aquariorum, 18 (19%) with A. caviae, 16 (17%) with A. hydrophila, 12 (13%) with A. veronii and one strain (1%) with the type strain of A. trota. PCR investigation revealed the presence of 10 virulence genes in the 94 isolates as: lip (91%), exu (87%), ela (86%), alt (79%), ser (77%), fla (74%), aer (72%), act (43%), aexT (24%) and ast (23%). Conclusions/Significance This study emphasizes the importance of using more than one method for the correct identification of Aeromonas strains. The sequences of the rpoD gene enabled the unambiguous identication of the 94 Aeromonas isolates in accordance with results of other recent studies. Aeromonas aquariorum showed to be the most prevalent species (50%) containing an important subset of virulence genes lip/alt/ser/fla/aer. Different combinations of the virulence genes present in the isolates indicate their probable role in the pathogenesis of Aeromonas infections.
Collapse
Affiliation(s)
- S D Puthucheary
- Department of Medical Microbiology, Faculty of Medicine, University of Malaya, Kuala Lumpur, Malaysia
| | | | | |
Collapse
|
26
|
The Photobacterium damselae subsp. damselae hemolysins damselysin and HlyA are encoded within a new virulence plasmid. Infect Immun 2011; 79:4617-27. [PMID: 21875966 DOI: 10.1128/iai.05436-11] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Photobacterium damselae subsp. damselae (formerly Vibrio damsela) is a marine bacterium that causes infections and fatal disease in a wide range of marine animals and in humans. Highly hemolytic strains produce damselysin (Dly), a cytolysin encoded by the dly gene that is lethal for mice and has hemolytic activity. We found that Dly is encoded in the highly hemolytic strain RM-71 within a 153,429-bp conjugative plasmid that we dubbed pPHDD1. In addition to Dly, pPHDD1 also encodes a homologue of the pore-forming toxin HlyA. We found a direct correlation between presence of pPHDD1 and a strong hemolytic phenotype in a collection of P. damselae subsp. damselae isolates. Hemolysis was strongly reduced in a double dly hlyA mutant, demonstrating the role of the two pPHDD1-encoded genes in hemolysis. Interestingly, although single hlyA and dly mutants showed different levels of hemolysis reduction depending on the erythrocyte source, hemolysis was not abolished in any of the single mutants, suggesting that the hemolytic phenotype is the result of the additive effect of Dly and HlyA. We found that pPHDD1-encoded dly and hlyA genes are necessary for full virulence for mice and fish. Our results suggest that pPHDD1 can be considered as a driving force for the emergence of a highly hemolytic lineage of P. damselae subsp. damselae.
Collapse
|
27
|
Figueras MJ, Beaz-Hidalgo R, Senderovich Y, Laviad S, Halpern M. Re-identification of Aeromonas isolates from chironomid egg masses as the potential pathogenic bacteria Aeromonas aquariorum. ENVIRONMENTAL MICROBIOLOGY REPORTS 2011; 3:239-244. [PMID: 23761256 DOI: 10.1111/j.1758-2229.2010.00216.x] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Egg masses of the non-biting midge Chironomous sp. have recently been found to serve as a reservoir for Vibrio cholerae and Aeromonas species. These insects are widely distributed in freshwater and evidence suggests that they may disseminate pathogenic bacteria species into drinking water systems. In the current study the taxonomy of 26 Aeromonas isolates, previously recovered from chironomid egg masses, was re-evaluated. It was found that 23 isolates, which had previously been identified as Aeromonas caviae, could belong to the recently described species Aeromonas aquariorum by their biochemical traits. To date, A. aquariorum has been found in ornamental fish and also in human extra-intestinal infections. ERIC-PCR genotyping differentiated 11 strains within the 23 A. aquariorum isolates, whose identity was confirmed by their rpoD gene sequences. Strains were found to possess the following virulence-associated genes: alt (90.9%), ahpB (81.8%), pla/lip/lipH3/apl-1/lip (54.5%), fla (27.3%), act/hylA/aerA (27.3%), ascF-ascG (81.8%) and aexT (9%) encoding for the cytotonic heat-labile enterotoxin, elastase, lipase, flagella, cytotoxic enterotoxins, the Type III Secretion System and the AexT toxin delivered by this system respectively. These findings indicate that chironomid egg masses harbour strains of A. aquariorum, which bear an important number of virulence genes, and that this species was misidentified originally as A. caviae.
Collapse
Affiliation(s)
- Maria José Figueras
- Unitat de Microbiologia, Departament de Ciènces Médiques Bàsiques, Facultat de Medicina I Ciències de la Salut, IISPV, Universitat Rovira I Virgili, Reus, Spain Department of Biology, Faculty of Natural Sciences, University of Haifa, Oranim, Tivon 36006, Israel
| | | | | | | | | |
Collapse
|
28
|
Elhariry HM. Biofilm formation by Aeromonas hydrophila on green-leafy vegetables: cabbage and lettuce. Foodborne Pathog Dis 2011; 8:125-31. [PMID: 21034267 DOI: 10.1089/fpd.2010.0642] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Aeromonas hydrophila is the most well known of the six species of Aeromonas, which has been linked to two groups of human diseases: septicemia and gastroenteritis. Reference strain ATCC 7966 and biofilm strains TUB19, TUB20, and TUB21 were investigated for their ability to form biofilm in vitro (after 48 h on polystyrene surface) and on the surface of two green-leafy vegetables, cabbage and lettuce (after 1, 2, 4, and 24 h). Attachment strength (S(R)) of these strains to the vegetable surface was also measured in the same time intervals. The ATCC 7966 and TUB19 had high ability to form biofilm in vitro compared with TUB20 and TUB21 in full strength tryptone soy broth or under starvation conditions in diluted tryptone soy broth (1:20, v/v). Cell surface hydrophobicity of the biofilm strains was lower than that of the reference strain. The biofilm of all tested strains on polystyrene surfaces differed from that on the vegetable surfaces. All strains studied rapidly attached to both green leafy vegetables (after 1 h). S(R) and cell populations (loosely and strongly attached cells) significantly (p < 0.05) increased with contact time; however, no significant (p > 0.05) differences in cell populations were recorded after 4 and 24 h. The highest S(R) and cell population (log CFU cm⁻²) were recorded by TUB19. In conclusion, the use of A. hydrophila strains isolated from environmental biofilm samples may be more useful for understanding biofilm formation on green-leafy vegetables than the reference or laboratory strains. The attachment of A. hydrophila was significantly affected by the surfaces of green-leafy vegetables. Further studies are required to improve our understanding of the interaction between human microbial pathogens and surfaces of raw vegetables.
Collapse
Affiliation(s)
- Hesham M Elhariry
- Department of Biology, Faculty of Science, Taif University, Taif, Kingdom of Saudi Arabia.
| |
Collapse
|
29
|
Noonin C, Jiravanichpaisal P, Söderhäll I, Merino S, Tomás JM, Söderhäll K. Melanization and pathogenicity in the insect, Tenebrio molitor, and the crustacean, Pacifastacus leniusculus, by Aeromonas hydrophila AH-3. PLoS One 2010; 5:e15728. [PMID: 21206752 PMCID: PMC3012084 DOI: 10.1371/journal.pone.0015728] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2010] [Accepted: 11/22/2010] [Indexed: 12/27/2022] Open
Abstract
Aeromonas hydrophila is the most common Aeromonas species causing infections in human and other animals such as amphibians, reptiles, fish and crustaceans. Pathogenesis of Aeromonas species have been reported to be associated with virulence factors such as lipopolysaccharides (LPS), bacterial toxins, bacterial secretion systems, flagella, and other surface molecules. Several mutant strains of A. hydrophila AH-3 were initially used to study their virulence in two animal species, Pacifastacus leniusculus (crayfish) and Tenebrio molitor larvae (mealworm). The AH-3 strains used in this study have mutations in genes involving the synthesis of flagella, LPS structures, secretion systems, and some other factors, which have been reported to be involved in A. hydrophila pathogenicity. Our study shows that the LPS (O-antigen and external core) is the most determinant A. hydrophila AH-3 virulence factor in both animals. Furthermore, we studied the immune responses of these hosts to infection of virulent or non-virulent strains of A. hydrophila AH-3. The AH-3 wild type (WT) containing the complete LPS core is highly virulent and this bacterium strongly stimulated the prophenoloxidase activating system resulting in melanization in both crayfish and mealworm. In contrast, the ΔwaaE mutant which has LPS without O-antigen and external core was non-virulent and lost ability to stimulate this system and melanization in these two animals. The high phenoloxidase activity found in WT infected crayfish appears to result from a low expression of pacifastin, a prophenoloxidase activating enzyme inhibitor, and this gene expression was not changed in the ΔwaaE mutant infected animal and consequently phenoloxidase activity was not altered as compared to non-infected animals. Therefore we show that the virulence factors of A. hydrophila are the same regardless whether an insect or a crustacean is infected and the O-antigen and external core is essential for activation of the proPO system and as virulence factors for this bacterium.
Collapse
Affiliation(s)
- Chadanat Noonin
- Department of Comparative Physiology, Uppsala University, Uppsala, Sweden
| | - Pikul Jiravanichpaisal
- Department of Comparative Physiology, Uppsala University, Uppsala, Sweden
- National Center for Genetic Engineering and Biotechnology, National Science and Technology Development Agency, Bangkok, Thailand
| | - Irene Söderhäll
- Department of Comparative Physiology, Uppsala University, Uppsala, Sweden
| | - Susana Merino
- Departamento de Microbiología, Facultad de Biología, Universidad de Barcelona, Barcelona, Spain
| | - Juan M. Tomás
- Departamento de Microbiología, Facultad de Biología, Universidad de Barcelona, Barcelona, Spain
| | - Kenneth Söderhäll
- Department of Comparative Physiology, Uppsala University, Uppsala, Sweden
- * E-mail:
| |
Collapse
|
30
|
Distribution of virulence factors and molecular fingerprinting of Aeromonas species isolates from water and clinical samples: suggestive evidence of water-to-human transmission. Appl Environ Microbiol 2010; 76:2313-25. [PMID: 20154106 DOI: 10.1128/aem.02535-09] [Citation(s) in RCA: 106] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
A total of 227 isolates of Aeromonas obtained from different geographical locations in the United States and different parts of the world, including 28 reference strains, were analyzed to determine the presence of various virulence factors. These isolates were also fingerprinted using biochemical identification and pulse-field gel electrophoresis (PFGE). Of these 227 isolates, 199 that were collected from water and clinical samples belonged to three major groups or complexes, namely, the A. hydrophila group, the A. caviae-A. media group, and the A. veronii-A. sobria group, based on biochemical profiles, and they had various pulsotypes. When virulence factor activities were examined, Aeromonas isolates obtained from clinical sources had higher cytotoxic activities than isolates obtained from water sources for all three Aeromonas species groups. Likewise, the production of quorum-sensing signaling molecules, such as N-acyl homoserine lactone, was greater in clinical isolates than in isolates from water for the A. caviae-A. media and A. hydrophila groups. Based on colony blot DNA hybridization, the heat-labile cytotonic enterotoxin gene and the DNA adenosine methyltransferase gene were more prevalent in clinical isolates than in water isolates for all three Aeromonas groups. Using colony blot DNA hybridization and PFGE, we obtained three sets of water and clinical isolates that had the same virulence signature and had indistinguishable PFGE patterns. In addition, all of these isolates belonged to the A. caviae-A. media group. The findings of the present study provide the first suggestive evidence of successful colonization and infection by particular strains of certain Aeromonas species after transmission from water to humans.
Collapse
|
31
|
Bhowmik P, Bag PK, Hajra TK, De R, Sarkar P, Ramamurthy T. Pathogenic potential of Aeromonas hydrophila isolated from surface waters in Kolkata, India. J Med Microbiol 2009; 58:1549-1558. [DOI: 10.1099/jmm.0.014316-0] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Members of the genus Aeromonas (family Aeromonadaceae) are medically important, Gram-negative, rod-shaped micro-organisms and are ubiquitous in aquatic environments. Aeromonas species are increasingly recognized as enteric pathogens; they possess several virulence factors associated with human disease, and represent a serious public health concern. In the present study, putative virulence traits of Aeromonas hydrophila isolates collected from different natural surface waters of Kolkata, India, were compared with a group of clinical isolates from the same geographical area using tissue culture and PCR assays. Enteropathogenic potential was investigated in the mouse model. Of the 21 environmental isolates tested, the majority showed cytotoxicity to HeLa cells (81 %), haemolysin production (71 %) and serum resistance properties (90 %), and they all exhibited multi-drug resistance. Some of the isolates induced fluid accumulation (FA ratio≥100), damage to the gut and an inflammatory reaction in the mouse intestine; these effects were comparable to those of clinical strains of A. hydrophila and toxigenic Vibrio cholerae. Interestingly, two of the isolates evoked a cell vacuolation effect in HeLa cells, and were also able to induce FA. These findings demonstrate the presence of potentially pathogenic and multi-drug-resistant A. hydrophila in the surface waters, thereby indicating a significant risk to public health. Continuous monitoring of surface waters is important to identify potential water-borne pathogens and to reduce the health risk caused by the genus Aeromonas.
Collapse
Affiliation(s)
- Poulami Bhowmik
- Department of Biochemistry, University of Calcutta, 35 Ballygunge Circular Road, Kolkata 700 019, India
| | - Prasanta K. Bag
- Department of Biochemistry, University of Calcutta, 35 Ballygunge Circular Road, Kolkata 700 019, India
| | - Tapas K. Hajra
- Department of Biochemistry, University of Calcutta, 35 Ballygunge Circular Road, Kolkata 700 019, India
| | - Rituparna De
- National Institute of Cholera and Enteric Diseases, P-33 C.I.T. Road, Scheme-XM, Beliaghata, Kolkata 700 010, India
| | - Pradipto Sarkar
- Department of Biochemistry, University of Calcutta, 35 Ballygunge Circular Road, Kolkata 700 019, India
| | - T. Ramamurthy
- National Institute of Cholera and Enteric Diseases, P-33 C.I.T. Road, Scheme-XM, Beliaghata, Kolkata 700 010, India
| |
Collapse
|
32
|
Cabrera Z, Fernandez-Lorente G, Palomo JM, Guisan JM, Fernandez-Lafuente R. Asymmetric hydrolysis of dimethyl 3-phenylglutarate catalyzed by Lecitase Ultra®. Enzyme Microb Technol 2008. [DOI: 10.1016/j.enzmictec.2008.07.001] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
|
33
|
The genome of Aeromonas salmonicida subsp. salmonicida A449: insights into the evolution of a fish pathogen. BMC Genomics 2008; 9:427. [PMID: 18801193 PMCID: PMC2556355 DOI: 10.1186/1471-2164-9-427] [Citation(s) in RCA: 217] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2007] [Accepted: 09/18/2008] [Indexed: 12/04/2022] Open
Abstract
Background Aeromonas salmonicida subsp. salmonicida is a Gram-negative bacterium that is the causative agent of furunculosis, a bacterial septicaemia of salmonid fish. While other species of Aeromonas are opportunistic pathogens or are found in commensal or symbiotic relationships with animal hosts, A. salmonicida subsp. salmonicida causes disease in healthy fish. The genome sequence of A. salmonicida was determined to provide a better understanding of the virulence factors used by this pathogen to infect fish. Results The nucleotide sequences of the A. salmonicida subsp. salmonicida A449 chromosome and two large plasmids are characterized. The chromosome is 4,702,402 bp and encodes 4388 genes, while the two large plasmids are 166,749 and 155,098 bp with 178 and 164 genes, respectively. Notable features are a large inversion in the chromosome and, in one of the large plasmids, the presence of a Tn21 composite transposon containing mercury resistance genes and an In2 integron encoding genes for resistance to streptomycin/spectinomycin, quaternary ammonia compounds, sulphonamides and chloramphenicol. A large number of genes encoding potential virulence factors were identified; however, many appear to be pseudogenes since they contain insertion sequences, frameshifts or in-frame stop codons. A total of 170 pseudogenes and 88 insertion sequences (of ten different types) are found in the A. salmonicida genome. Comparison with the A. hydrophila ATCC 7966T genome reveals multiple large inversions in the chromosome as well as an approximately 9% difference in gene content indicating instances of single gene or operon loss or gain. A limited number of the pseudogenes found in A. salmonicida A449 were investigated in other Aeromonas strains and species. While nearly all the pseudogenes tested are present in A. salmonicida subsp. salmonicida strains, only about 25% were found in other A. salmonicida subspecies and none were detected in other Aeromonas species. Conclusion Relative to the A. hydrophila ATCC 7966T genome, the A. salmonicida subsp. salmonicida genome has acquired multiple mobile genetic elements, undergone substantial rearrangement and developed a significant number of pseudogenes. These changes appear to be a consequence of adaptation to a specific host, salmonid fish, and provide insights into the mechanisms used by the bacterium for infection and avoidance of host defence systems.
Collapse
|
34
|
Fernandez-Lorente G, Filice M, Terreni M, Guisan JM, Fernandez-Lafuente R, Palomo JM. Lecitase® ultra as regioselective biocatalyst in the hydrolysis of fully protected carbohydrates. ACTA ACUST UNITED AC 2008. [DOI: 10.1016/j.molcatb.2007.11.017] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
|
35
|
Suarez G, Sierra JC, Sha J, Wang S, Erova TE, Fadl AA, Foltz SM, Horneman AJ, Chopra AK. Molecular characterization of a functional type VI secretion system from a clinical isolate of Aeromonas hydrophila. Microb Pathog 2007; 44:344-61. [PMID: 18037263 DOI: 10.1016/j.micpath.2007.10.005] [Citation(s) in RCA: 167] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2007] [Revised: 10/17/2007] [Accepted: 10/18/2007] [Indexed: 01/01/2023]
Abstract
Our laboratory recently molecularly characterized the type II secretion system (T2SS)-associated cytotoxic enterotoxin (Act) and the T3SS-secreted AexU effector from a diarrheal isolate SSU of Aeromonas hydrophila. The role of these toxin proteins in the pathogenesis of A. hydrophila infections was subsequently delineated in in vitro and in vivo models. In this study, we characterized the new type VI secretion system (T6SS) from isolate SSU of A. hydrophila and demonstrated its role in bacterial virulence. Study of the role of T6SS in bacterial virulence is in its infancy, and there are, accordingly, only limited, recent reports directed toward a better understanding its role in bacterial pathogenesis. We have provided evidence that the virulence-associated secretion (vas) genes vasH (Sigma 54-dependent transcriptional regulator) and vasK (encoding protein of unknown function) are essential for expression of the genes encoding the T6SS and/or they constituted important components of the T6SS. Deletion of the vasH gene prevented expression of the potential translocon hemolysin coregulated protein (Hcp) encoding gene from bacteria, while the vasK gene deletion prevented secretion but not translocation of Hcp into host cells. The secretion of Hcp was independent of the T3SS and the flagellar system. We demonstrated that secreted Hcp could bind to the murine RAW 264.7 macrophages from outside, in addition to its ability to be translocated into host cells. Further, the vasH and vasK mutants were less toxic to murine macrophages and human epithelial HeLa cells, and these mutants were more efficiently phagocytosed by macrophages. We also provided evidence that the expression of the hcp gene in the HeLa cell resulted in apoptosis of the host cells. Finally, the vasH and vasK mutants of A. hydrophila were less virulent in a septicemic mouse model of infection, and animals immunized with recombinant Hcp were protected from subsequent challenge with the wild-type (WT) bacterium. In addition, mice infected with the WT A. hydrophila had circulating antibodies to Hcp, indicating an important role of T6SS in the pathogenesis of A. hydrophila infections. Taken together, we have characterized the T6SS from Aeromonas for the first time and provided new features of this secretion system not yet known for other pathogens.
Collapse
Affiliation(s)
- Giovanni Suarez
- Department of Microbiology and Immunology(,) University of Texas Medical Branch, 301 University Blvd., Galveston, TX 775551070, USA
| | | | | | | | | | | | | | | | | |
Collapse
|
36
|
Scoaris DDO, Colacite J, Nakamura CV, Ueda-Nakamura T, de Abreu Filho BA, Dias Filho BP. Virulence and antibiotic susceptibility of Aeromonas spp. isolated from drinking water. Antonie van Leeuwenhoek 2007; 93:111-22. [PMID: 17636377 DOI: 10.1007/s10482-007-9185-z] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/11/2007] [Accepted: 06/18/2007] [Indexed: 11/25/2022]
Abstract
Aeromonas isolates from tap water, mineral water, and artesian well water were investigated for their ability to produce different potential virulence factors or markers such as hemolysins, cytotoxins, phospholipase, DNase, hydrophobicity and their ability to adhere to epithelial cells and to abiotic surfaces. The susceptibility to antibiotics of Aeromonas isolates was also examined. Majority of the isolates displayed hemolytic activity against sheep erythrocytes, while only 7 of the 23 Aeromonas strains displayed DNase activity and 4 of the 23 Aeromonas strains tested were regarded as positive for phospholipase production. Most of the isolates showed cytotoxic activities in culture filtrate dilutions at titer of 1/8 or lower. No general relation between the strain isolated and the ability to interact with epithelial cells could be established. Using the bacterial adherence to hydrocarbons method, most of the strains were classified as highly hydrophilic. All five Aeromonas jandaei strains isolates, 9 of the 12 Aeromonas sp strains and four of the five Aeromonas hydrophila were multidrug resistant. The most active antimicrobial was ciprofloxacin (susceptible in 100% of the isolates), and the least active antibiotic was ampicillin (resistance in 92% of the isolates). The majority of the isolates tested were not killed by chlorine at 1.2 mg/l. Whether the high tolerance to chlorine of Aeromonas isolates can be linked to greater virulence is not know.
Collapse
Affiliation(s)
- Denise de Oliveira Scoaris
- Programa de Pós-graduação em Microbiologia, Universidade Estadual de Londrina, Rodovia Celso Garcia Cid, Pr 445 Km 380, Cx. Postal 6001, 86051-990, Londrina, PR, Brazil
| | | | | | | | | | | |
Collapse
|
37
|
Fernandez-Lorente G, Palomo JM, Guisan JM, Fernandez-Lafuente R. Effect of the immobilization protocol in the activity, stability, and enantioslectivity of Lecitase® Ultra. ACTA ACUST UNITED AC 2007. [DOI: 10.1016/j.molcatb.2007.04.008] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
|
38
|
Fadl AA, Galindo CL, Sha J, Zhang F, Garner HR, Wang HQ, Chopra AK. Global transcriptional responses of wild-type Aeromonas hydrophila and its virulence-deficient mutant in a murine model of infection. Microb Pathog 2007; 42:193-203. [PMID: 17368824 DOI: 10.1016/j.micpath.2007.02.002] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2006] [Revised: 12/12/2006] [Accepted: 02/02/2007] [Indexed: 11/25/2022]
Abstract
We previously generated a double knockout mutant (act/aopB) of a diarrheal isolate SSU of A. hydrophila, in which the genes encoding Aeromonas outer membrane protein B (AopB), a structural component of the type III secretion system (T3SS), and a type II (T2)-secreted cytotoxic enterotoxin gene (act) were deleted. This mutant exhibited minimal virulence in mice, compared to animals infected with wild-type (WT) A. hydrophila. Based on microarray analyses, WT A. hydrophila altered the expression of 434 and 80 genes in murine macrophages (RAW 264.7) and human colonic epithelial cells (HT-29), respectively. Approximately half of these gene expression alterations were abrogated when host cells were infected instead with the act/aopB mutant. In this study, we used microarrays to examine early host transcriptional responses in spleens of mice infected for 3h with WT A. hydrophila or its act/aopB mutant. Our data indicated that expression of 221 genes was altered (158 up-regulated and 63 down-regulated) in spleens of WT bacteria-infected animals. There were 21 genes that were consistently more highly expressed in WT A. hydrophila-infected mice, compared to mice infected with its act/aopB mutant. Ten of these genes were either induced to a lesser extent (e.g., interleukin-6, macrophage inflammatory protein-2, and cyclooxygenase-2), not altered at all (e.g., killer cell lectin-like receptor subfamily B member A), or down-regulated (e.g., cytochrome P450) in animals infected with A. hydrophila, compared to phosphate-buffered saline-infected control animals, when the mutant was used instead of the WT. We verified the microarray results at the transcript level by performing real-time reverse transcriptase-polymerase chain reaction on selected genes and at the protein level by enzyme-linked immunosorbent assay (ELISA) and immunohistochemistry. This is the first study demonstrating in vivo gene regulation in mice infected with A. hydrophila and the contribution of virulence factors and host responses to the disease process.
Collapse
Affiliation(s)
- Amin A Fadl
- Department of Microbiology and Immunology, Medical Research Building, 301 University Boulevard, University of Texas Medical Branch, Galveston, TX 77555-1070, USA
| | | | | | | | | | | | | |
Collapse
|
39
|
Debroy S, Aragon V, Kurtz S, Cianciotto NP. Legionella pneumophila Mip, a surface-exposed peptidylproline cis-trans-isomerase, promotes the presence of phospholipase C-like activity in culture supernatants. Infect Immun 2006; 74:5152-60. [PMID: 16926407 PMCID: PMC1594821 DOI: 10.1128/iai.00484-06] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The type II secretion system of Legionella pneumophila promotes pathogenesis. Among the Legionella type II-dependent exoenzymes is a p-nitrophenol phosphorylcholine (p-NPPC) hydrolase whose activity is only partially explained by the PlcA phospholipase C. In a screen to identify other factors that promote secreted hydrolase activity, we isolated a mip mutant. L. pneumophila Mip is a surface-exposed, FK506-binding protein that is needed for optimal infection and has peptidylproline cis-trans-isomerase (PPIase) activity. Since the molecular target of Mip was undefined, we investigated a possible relationship between Mip and the secreted p-NPPC hydrolase activity. In the mip mutant there was a 40 to 70% reduction in secreted activity that was successfully complemented by providing mip on a plasmid. A similar phenotype was observed when we examined four other independently derived mip mutants, and in all cases the defect was complemented by reintroduction of mip. Thus, mip promotes the presence of a p-NPPC hydrolase activity in culture supernatants. We also found that the C terminus of Mip is required for this effect. When supernatants were examined by anion-exchange chromatography, the p-NPPC hydrolase activity associated with Mip proved to be type II dependent but distinct from PlcA. This conclusion was supported by the phenotype of a newly constructed mip plcA double mutant. Thus, Mip promotes the elaboration of a new type II exoprotein. These data provide both the first evidence for a target for Mip and the first indication that a surface PPIase is involved in the secretion or activation of proteins beyond the outer membrane.
Collapse
Affiliation(s)
- Sruti Debroy
- Department of Microbiology-Immunology, Northwestern University Medical School, 320 East Superior Street, Chicago, IL 60611-3010, USA
| | | | | | | |
Collapse
|
40
|
Seshadri R, Joseph SW, Chopra AK, Sha J, Shaw J, Graf J, Haft D, Wu M, Ren Q, Rosovitz MJ, Madupu R, Tallon L, Kim M, Jin S, Vuong H, Stine OC, Ali A, Horneman AJ, Heidelberg JF. Genome sequence of Aeromonas hydrophila ATCC 7966T: jack of all trades. J Bacteriol 2006; 188:8272-82. [PMID: 16980456 PMCID: PMC1698176 DOI: 10.1128/jb.00621-06] [Citation(s) in RCA: 259] [Impact Index Per Article: 14.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The complete genome of Aeromonas hydrophila ATCC 7966(T) was sequenced. Aeromonas, a ubiquitous waterborne bacterium, has been placed by the Environmental Protection Agency on the Contaminant Candidate List because of its potential to cause human disease. The 4.7-Mb genome of this emerging pathogen shows a physiologically adroit organism with broad metabolic capabilities and considerable virulence potential. A large array of virulence genes, including some identified in clinical isolates of Aeromonas spp. or Vibrio spp., may confer upon this organism the ability to infect a wide range of hosts. However, two recognized virulence markers, a type III secretion system and a lateral flagellum, that are reported in other A. hydrophila strains are not identified in the sequenced isolate, ATCC 7966(T). Given the ubiquity and free-living lifestyle of this organism, there is relatively little evidence of fluidity in terms of mobile elements in the genome of this particular strain. Notable aspects of the metabolic repertoire of A. hydrophila include dissimilatory sulfate reduction and resistance mechanisms (such as thiopurine reductase, arsenate reductase, and phosphonate degradation enzymes) against toxic compounds encountered in polluted waters. These enzymes may have bioremediative as well as industrial potential. Thus, the A. hydrophila genome sequence provides valuable insights into its ability to flourish in both aquatic and host environments.
Collapse
Affiliation(s)
- Rekha Seshadri
- The Institute for Genomic Research, Division of J. Craig Venter Institute, Rockville, MD 20850,USA.
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
41
|
Pillai L, Sha J, Erova TE, Fadl AA, Khajanchi BK, Chopra AK. Molecular and functional characterization of a ToxR-regulated lipoprotein from a clinical isolate of Aeromonas hydrophila. Infect Immun 2006; 74:3742-55. [PMID: 16790746 PMCID: PMC1489700 DOI: 10.1128/iai.00402-06] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2006] [Revised: 04/10/2006] [Accepted: 04/18/2006] [Indexed: 11/20/2022] Open
Abstract
Human diseases caused by species of Aeromonas have been classified into two major groups: septicemia and gastroenteritis. In this study, we reported the molecular and functional characterization of a new virulence factor, ToxR-regulated lipoprotein, or TagA, from a diarrheal isolate, SSU, of Aeromonas hydrophila. The tagA gene of A. hydrophila exhibited 60% identity with that of a recently identified stcE gene from Escherichia coli O157:H7, which encoded a protein (StcE) that provided serum resistance to the bacterium and prevented erythrocyte lysis by controlling classical pathway of complement activation by cleaving the complement C1-esterase inhibitor (C1-INH). We purified A. hydrophila TagA as a histidine-tagged fusion protein (rTagA) from E. coli DE3 strain using a T7 promoter-based pET30 expression vector and nickel affinity column chromatography. rTagA cleaved C1-INH in a time-dependent manner. The tagA isogenic mutant of A. hydrophila, unlike its corresponding wild-type (WT) or the complemented strain, was unable to cleave C1-INH, which is required to potentiate the C1-INH-mediated lysis of host and bacterial cells. We indeed demonstrated colocalization of C1-INH and TagA on the bacterial surface by confocal fluorescence microscopy, which ultimately resulted in increased serum resistance of the WT bacterium. Likewise, we delineated the role of TagA in contributing to the enhanced ability of C1-INH to inhibit the classical complement-mediated lysis of erythrocytes. Importantly, we provided evidence that the tagA mutant was significantly less virulent in a mouse model of infection (60%) than the WT bacterium at two 50% lethal doses, which resulted in 100% mortality within 48 h. Taken together, our data provided new information on the role of TagA as a virulence factor in bacterial pathogenesis. This is the first report of TagA characterization from any species of Aeromonas.
Collapse
Affiliation(s)
- Lakshmi Pillai
- Department of Microbiology and Immunology, Medical Research Building, 301 University Boulevard, University of Texas Medical Branch, Galveston, TX 77555-1070, USA
| | | | | | | | | | | |
Collapse
|
42
|
Fadl AA, Galindo CL, Sha J, Erova TE, Houston CW, Olano JP, Chopra AK. Deletion of the genes encoding the type III secretion system and cytotoxic enterotoxin alters host responses to Aeromonas hydrophila infection. Microb Pathog 2006; 40:198-210. [PMID: 16626931 DOI: 10.1016/j.micpath.2006.01.003] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2005] [Revised: 01/09/2006] [Accepted: 01/16/2006] [Indexed: 12/21/2022]
Abstract
In our previous study, we deleted the gene encoding Aeromonas outer membrane protein B (AopB), a structural component of the type III secretion system (T3SS) from a cytotoxic enterotoxin gene (act)-minus diarrheal isolate SSU of Aeromonas hydrophila. Our laboratory also molecularly characterized the cytotoxic enterotoxin (Act), which is secreted by the bacterium utilizing the type II secretion system (T2SS). The act/aopB mutant exhibited significantly reduced cytotoxicity to cultured cells (e.g. RAW 264.7 murine macrophages and HT-29 human colonic epithelial cells) and was avirulent in mice. In this study, we developed additional A. hydrophila mutants in which T3SS-associated ascV and acrV genes were deleted, either individually or in combination with that of the act gene, to examine host-pathogen interactions. A significant reduction in the induction of inflammatory cytokines and chemokines was noted in the sera of mice infected with these mutants when compared to animals infected with wild-type (WT) A. hydrophila. After infection with the WT and act/aopB mutant, we performed microarray analyses on RNA from the above-mentioned murine macrophages and human colonic epithelial cells to examine global cellular transcriptional responses. Based on three independent experiments, WT A. hydrophila altered the expression of 434 genes in RAW 264.7 cells and 80 genes in HT-29 cells. Alteration in the expression of 209 macrophage and 32 epithelial cell genes was reduced when the act/aopB mutant was used, compared to when cells were infected with the WT bacterium, indicating the involvement of Act and/or AopB in transcriptional regulation of these genes. We verified up-regulation of 15 genes by real-time reverse transcriptase-polymerase chain reaction and confirmed A. hydrophila WT-versus mutant-induced production of cytokines/chemokines in supernatants from RAW 264.7 and HT-29 cells. This is the first description of host cell transcriptional responses to A. hydrophila infection.
Collapse
Affiliation(s)
- Amin A Fadl
- Department of Microbiology and Immunology, The University of Texas Medical Branch, Medical Research Building, 301 University Boulevard, Galveston, TX 77555-1070, USA
| | | | | | | | | | | | | |
Collapse
|
43
|
Galindo CL, Gutierrez C, Chopra AK. Potential involvement of galectin-3 and SNAP23 in Aeromonas hydrophila cytotoxic enterotoxin-induced host cell apoptosis. Microb Pathog 2006; 40:56-68. [PMID: 16426811 DOI: 10.1016/j.micpath.2005.11.001] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2005] [Revised: 11/03/2005] [Accepted: 11/07/2005] [Indexed: 11/23/2022]
Abstract
We investigated the potential of the cytotoxic enterotoxin (Act) of Aeromonas hydrophila to bind to 1869 human and 4319 yeast proteins, using protein microarray technology. Act was capable of binding nine different human proteins, including the SNARE complex scaffolding protein synaptosomal-associated protein 23 (SNAP23), galectin-3, and guanylate kinase 1 (GUK-1). Act was also able to bind to four of the yeast proteins examined, which included the vesicle tethering protein Vsp52. We verified interaction of Act with murine and human SNAP23, galectin-3, and GUK-1 by sandwich Western blot analysis. In order to determine the physiological relevance of Act binding to these three proteins, we performed small interfering RNA (siRNA) gene knockdown experiments in RAW 264.7 cells, a murine macrophage cell line in which Act-induced signaling and cell death is well characterized. Based on real-time reverse transcriptase-polymerase chain reaction, siRNA transfection of RAW 264.7 cells with specific oligonucleotides reduced the expression of genes encoding SNAP23, galectin-3, and GUK-1 by 62, 63, and 99%, respectively. Knockdown of galectin-3 and SNAP23, but not GUK-1, significantly reduced Act-induced apoptosis of host cells, as determined by TUNEL (TdT-mediated dUTP nick end labeling) assay, lactate dehydrogenase release, Giemsa staining, and reduction in activation of caspase 3, compared to toxin-treated macrophages that were transfected with a random sequence control siRNA. We also performed these assays using a human intestinal epithelial cell line (HT-29) and observed a similar trend of galectin-3 and SNAP23 association with Act-induced apoptosis. This is the first report of putative protein binding partners for this toxin and potential mediators/regulators of Act-induced apoptosis.
Collapse
Affiliation(s)
- C L Galindo
- Department of Microbiology and Immunology, The University of Texas Medical Branch, Medical Research Building, 301 University Boulevard, Galveston, Texas 77555-1070, USA
| | | | | |
Collapse
|
44
|
Yu HB, Zhang YL, Lau YL, Yao F, Vilches S, Merino S, Tomas JM, Howard SP, Leung KY. Identification and characterization of putative virulence genes and gene clusters in Aeromonas hydrophila PPD134/91. Appl Environ Microbiol 2005; 71:4469-77. [PMID: 16085838 PMCID: PMC1183340 DOI: 10.1128/aem.71.8.4469-4477.2005] [Citation(s) in RCA: 71] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Aeromonas hydrophila is a gram-negative opportunistic pathogen of animals and humans. The pathogenesis of A. hydrophila is multifactorial. Genomic subtraction and markers of genomic islands (GIs) were used to identify putative virulence genes in A. hydrophila PPD134/91. Two rounds of genomic subtraction led to the identification of 22 unique DNA fragments encoding 19 putative virulence factors and seven new open reading frames, which are commonly present in the eight virulence strains examined. In addition, four GIs were found, including O-antigen, capsule, phage-associated, and type III secretion system (TTSS) gene clusters. These putative virulence genes and gene clusters were positioned on a physical map of A. hydrophila PPD134/91 to determine their genetic organization in this bacterium. Further in vivo study of insertion and deletion mutants showed that the TTSS may be one of the important virulence factors in A. hydrophila pathogenesis. Furthermore, deletions of multiple virulence factors such as S-layer, serine protease, and metalloprotease also increased the 50% lethal dose to the same level as the TTSS mutation (about 1 log) in a blue gourami infection model. This observation sheds light on the multifactorial and concerted nature of pathogenicity in A. hydrophila. The large number of putative virulence genes identified in this study will form the basis for further investigation of this emerging pathogen and help to develop effective vaccines, diagnostics, and novel therapeutics.
Collapse
Affiliation(s)
- H B Yu
- Department of Biological Sciences, Faculty of Science, National University of Singapore, Science Drive 4, Singapore 117543, Republic of Singapore
| | | | | | | | | | | | | | | | | |
Collapse
|
45
|
Hauer PJ, Yeary TJ, Rosenbusch RF. Evidence of the protective immunogenicity of native and recombinant Clostridium haemolyticum phospholipase C (beta toxin) in guinea pigs. Vaccine 2005; 24:124-32. [PMID: 16140435 DOI: 10.1016/j.vaccine.2005.07.101] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2005] [Accepted: 07/28/2005] [Indexed: 11/19/2022]
Abstract
The immunogenic effects of the beta toxin of Clostridium haemolyticum were investigated in guinea pigs. Guinea pigs passively immunized with toxin-neutralizing monoclonal antibodies were protected from a 100 LD(50) spore challenge that was lethal to nonvaccinated controls. Guinea pigs actively immunized with varying doses of immunoaffinity-purified native beta toxin were similarly protected. In a third experiment, a recombinant toxoid was prepared from E. coli expressing the beta toxin gene. Guinea pigs immunized three times with recombinant toxoid also were protected against challenge. In each experiment, protection was correlated to the presence of anti-beta toxin antibodies in the serum. Taken together, these results indicate that a neutralizing antibody response to the beta toxin is a key component of protective immunity to C. haemolyticum in guinea pigs.
Collapse
Affiliation(s)
- Paul J Hauer
- Center for Veterinary Biologics, Veterinary Services, Animal and Plant Health Inspection Service, United States Department of Agriculture, Ames, IA 50010, USA.
| | | | | |
Collapse
|
46
|
Galindo CL, Fadl AA, Sha J, Pillai L, Gutierrez C, Chopra AK. Microarray and proteomics analyses of human intestinal epithelial cells treated with the Aeromonas hydrophila cytotoxic enterotoxin. Infect Immun 2005; 73:2628-43. [PMID: 15845465 PMCID: PMC1087361 DOI: 10.1128/iai.73.5.2628-2643.2005] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
We performed microarray analyses on RNA from human intestinal epithelial (HT-29) cells treated with the cytotoxic enterotoxin (Act) of Aeromonas hydrophila to examine global cellular transcriptional responses. Based on three independent experiments, Act upregulated the expression of 34 genes involved in cell growth, adhesion, signaling, immune responses (including interleukin-8 [IL-8] production), and apoptosis. We verified the upregulation of 14 genes by real-time reverse transcriptase-PCR and confirmed Act-induced production of IL-8 by enzyme-linked immunosorbent assay on supernatants from nonpolarized and polarized HT-29 cells. Maximal production of IL-8 in response to Act required the presence of intracellular calcium, since chelation of calcium with BAPTA-AM significantly reduced Act-induced IL-8 production in HT-29 cells. We also examined activation of mitogen-activated protein kinases and, as demonstrated by Western blot analysis of apical side-treated polarized HT-29 cells, Act induced phosphorylation of p38, c-Jun NH(2)-terminal kinase, and extracellular signal-regulated kinase 1/2. In addition, KinetWorks proteomics screening of whole-cell lysates revealed Act-induced phosphorylation of cyclic AMP-response element binding protein (CREB), c-Jun, adducin, protein kinase C, and signal transducer and activator of transcription 3 (STAT3) and decreased phosphorylation of protein kinase Balpha, v-raf-1 murine leukemia viral oncogene homolog 1 (i.e., Raf1), and STAT1. We verified activation of CREB and activator protein 1 in polarized cells by gel shift assay. This is the first description of human intestinal epithelial cell transcriptional alterations, phosphorylation or activation of signaling molecules, cytokine production, and calcium mobilization in response to this toxin.
Collapse
Affiliation(s)
- C L Galindo
- Department of Microbiology and Immunology, Medical Research Building, 301 University Blvd., University of Texas Medical Branch, Galveston, TX 77555-1070, USA
| | | | | | | | | | | |
Collapse
|
47
|
Wahli T, Burr SE, Pugovkin D, Mueller O, Frey J. Aeromonas sobria, a causative agent of disease in farmed perch, Perca fluviatilis L. JOURNAL OF FISH DISEASES 2005; 28:141-150. [PMID: 15752274 DOI: 10.1111/j.1365-2761.2005.00608.x] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Significant numbers of perch, Perca fluviatilis, raised on a pilot fish farm in Switzerland presented focal skin lesions on the lateral sides and fin rot. Mortality rates reached levels of up to 1% of the total fish on the farm per day. Virtually pure cultures of Aeromonas sobria were isolated from the liver, kidney, spleen and skin lesions of affected fish. Aeromonas sobria isolated from the farmed perch had a haemolytic effect on sheep and trout erythrocytes, autoaggregated, was cytotoxic for cultured fish cells and possessed genes involved in type III protein secretion. Experimental infection of naive perch with a single colony isolate of A. sobria from an affected farm fish resulted in the development of clinical signs identical to those seen on the farm. The results indicate that A. sobria can act as a primary pathogen of perch.
Collapse
Affiliation(s)
- T Wahli
- Centre for Fish and Wildlife Health, Institute of Animal Pathology, University of Berne, Berne, Switzerland.
| | | | | | | | | |
Collapse
|
48
|
Vilches S, Urgell C, Merino S, Chacón MR, Soler L, Castro-Escarpulli G, Figueras MJ, Tomás JM. Complete type III secretion system of a mesophilic Aeromonas hydrophila strain. Appl Environ Microbiol 2005; 70:6914-9. [PMID: 15528564 PMCID: PMC525241 DOI: 10.1128/aem.70.11.6914-6919.2004] [Citation(s) in RCA: 71] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
We have investigated the existence and genetic organization of a functional type III secretion system (TTSS) in a mesophilic Aeromonas strain by initially using the Aeromonas hydrophila strain AH-3. We report for the first time the complete TTSS DNA sequence of an Aeromonas strain that comprises 35 genes organized in a similar disposition as that in Pseudomonas aeruginosa. Using several gene probes, we also determined the presence of a TTSS in clinical or environmental strains of different Aeromonas species: A. hydrophila, A. veronii, and A. caviae. By using one of the TTSS genes (ascV), we were able to obtain a defined insertion mutant in strain AH-3 (AH-3AscV), which showed reduced toxicity and virulence in comparison with the wild-type strain. Complementation of the mutant strain with a plasmid vector carrying ascV was fully able to restore the wild-type toxicity and virulence.
Collapse
Affiliation(s)
- Silvia Vilches
- Departamento Microbiología, Facultad Biología, Universidad de Barcelona, Barcelona, Spain
| | | | | | | | | | | | | | | |
Collapse
|
49
|
Sen K, Rodgers M. Distribution of six virulence factors in Aeromonas species isolated from US drinking water utilities: a PCR identification. J Appl Microbiol 2005; 97:1077-86. [PMID: 15479425 DOI: 10.1111/j.1365-2672.2004.02398.x] [Citation(s) in RCA: 150] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
AIMS To examine whether Aeromonas bacteria isolated from municipally treated water had virulence factor genes. METHODS AND RESULTS A polymerase chain reaction-based genetic characterization determined the presence of six virulence factors genes, elastase (ahyB), lipase (pla/lip/lipH3/alp-1) flagella A and B (flaA and flaB), the enterotoxins, act, alt and ast, in these isolates. New primer sets were designed for all the target genes, except for act. The genes were present in 88% (ahyB), 88% (lip), 59% (fla), 43% (alt), 70% (act) and 30% (ast) of the strains, respectively. Of the 205 isolates tested only one isolate had all the virulence genes. There was a variety of combinations of virulence factors within different strains of the same species. However, a dominant strain having the same set of virulence factors, was usually isolated from any given tap in different rounds of sampling from a single tap. CONCLUSIONS These results show that Aeromonas bacteria found in drinking water possess a wide variety of virulence-related genes and suggest the importance of examining as many isolates as possible in order to better understand the health risk these bacteria may present. SIGNIFICANCE AND IMPACT OF THE STUDY This study presents a rapid method for characterizing the virulence factors of Aeromonas bacteria and suggests that municipally treated drinking water is a source of potentially pathogenic Aeromonas bacteria.
Collapse
Affiliation(s)
- K Sen
- Technical Support Center, Office of Water, USA EPA, Cincinnati, OH 45268, USA.
| | | |
Collapse
|
50
|
Hauer PJ, Yeary TJ, Rosenbusch RF. Cloning and molecular characterization of the beta toxin (phospholipase C) gene of Clostridium haemolyticum. Anaerobe 2004; 10:243-54. [PMID: 16701524 DOI: 10.1016/j.anaerobe.2004.04.006] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2004] [Accepted: 04/29/2004] [Indexed: 11/18/2022]
Abstract
The phospholipase C (PLPC) gene from Clostridium haemolyticum was amplified using the polymerase chain reaction. Primers were selected from a consensus sequence of closely related clostridial PLPC genes and used to amplify an 871-base pair internal segment of the gene. The internal sequence was used to design nested primers that, together with adapter-specific primers, were used to amplify upstream and downstream sequences. The sequences of upstream and downstream segments were aligned with the internal segment to obtain the entire gene sequence. Primers were selected from the aligned sequence, and the entire gene was amplified, and the PCR product was inserted by ligatation into the pCR 2.1 plasmid. An open reading frame that encodes a 399-amino acid protein, containing a 27-amino acid signal sequence, was identified (GenBank Accession Number AF525415). The molecular weight of the active protein was 42869 Da. A 16-amino acid N-terminal sequence, determined by Edman degradation, exactly matched the putative amino acid sequence of the gene product. Together, N-terminal peptide sequencing and tryptic digestion followed by MALDI-ToF mass spectroscopy verified 48% of the amino acid sequences of the active beta toxin. Comparison of the nucleotide and amino acid sequences with Gene-bank databases demonstrated that the beta toxin of C. haemolyticum exhibits high homology with other bacterial PLPCs. The N-terminal portion of the beta toxin contains zinc-binding residues common to clostridial and other bacterial PLPCs, and it shows 34% homology to the N-terminal domain of bovine arachidonate 5-lipoxygenase. The C-terminal domain of the beta toxin protein shows considerable homology with the C-terminal domains of C. novyi type A PLPC, C. perfringens alpha toxin, C. bifermentens PLPC, although the percent identity between the N-terminal regions is much higher overall than that in the C-terminal domain.
Collapse
Affiliation(s)
- Paul J Hauer
- Center for Veterinary Biologics, Veterinary Services, Animal and Plant Health Inspection Service, United Stated Department of Agriculture, 510 South 17th Street, Suite 104, Ames, IA 50010, USA.
| | | | | |
Collapse
|