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1.
J Bacteriol ; 194(3): 740-1, 2012 Feb.
Article in English | MEDLINE | ID: mdl-22247535

ABSTRACT

Edwardsiella ictaluri is the cause of extensive mortalities and economic losses to the channel catfish industry of the southeast United States. Here we report the complete genome of Edwardsiella ictaluri 93-146. Whole-genome sequence analysis of E. ictaluri provides a tool for understanding the genomic regions specific to the species and the Edwardsiella genus.


Subject(s)
Edwardsiella ictaluri/genetics , Enterobacteriaceae Infections/veterinary , Fish Diseases/microbiology , Genome, Bacterial , Ictaluridae , Sepsis/veterinary , Animals , Base Sequence , Disease Outbreaks , Edwardsiella ictaluri/classification , Edwardsiella ictaluri/isolation & purification , Enterobacteriaceae Infections/epidemiology , Enterobacteriaceae Infections/microbiology , Fish Diseases/epidemiology , Molecular Sequence Data , Sepsis/epidemiology , Sepsis/microbiology , United States/epidemiology
2.
Plasmid ; 45(1): 52-6, 2001 Jan.
Article in English | MEDLINE | ID: mdl-11319932

ABSTRACT

To determine possible functions of the Edwardsiella ictaluri plasmids, pEI1 and pEI2, we analyzed the sequence of both plasmids. Plasmid pEI1 is 4807 bp, with 51% G + C, and 23 possible open reading frames of 40 amino acids or greater. Plasmid pEI2 is 5643 bp, with 51% G + C, and 24 possible reading frames. Database searches indicated that pEI1 contains an insertion element and a ROM analog. In addition, pEI1 possesses an open reading frame with strong homology to SlrP, SspH1, and SspH2 of Salmonella typhimurium and IpaH of Shigella flexnari, which have leucine-rich repeat regions and are components of type III secretory systems. pEI2 has a frame with weak homology to Spa15 of S. flexnari 5 and InvB of S. sonnei and S. typhimurium, which are also type III secretory system components, three origins of replication, a Rep analog, and a multimer resolution site.


Subject(s)
Bacterial Proteins/genetics , Edwardsiella ictaluri/genetics , Plasmids/genetics , Bacterial Proteins/chemistry , DNA Transposable Elements/genetics , Leucine-Rich Repeat Proteins , Open Reading Frames , Proteins/genetics
3.
Infect Immun ; 65(11): 4642-51, 1997 Nov.
Article in English | MEDLINE | ID: mdl-9353045

ABSTRACT

In this study, an adenine-auxotrophic strain of Edwardsiella ictaluri was constructed and its virulence, tissue persistence, and vaccine efficacy were evaluated. A clone containing the purA gene was isolated from an E. ictaluri genomic library, sequenced, and shown to have an overall sequence identity of 79.3% at the nucleotide level and 85.7% at the amino acid level with the Escherichia coli purA gene. The cloned E. ictaluri purA gene was mutated by deleting a 598-bp segment of the gene and inserting the kanamycin resistance gene from Tn903 into the gap. The delta purA::Km(r) gene was subcloned into the suicide plasmid pGP704, and the resulting plasmid was used to deliver the modified gene into a virulent strain of E. ictaluri by conjugation. Homologous recombination replaced the chromosomal purA gene with the mutated gene to create an adenine-auxotrophic strain (LSU-E2). Compared to wild-type E. ictaluri, LSU-E2 was highly attenuated by the injection, immersion, and oral routes of exposure. By the injection route, LSU-E2 had a 50% lethal dose (LD50) that was greater than 5 logs10 higher than the LD50 for wild-type E. ictaluri. In a tissue persistence study, LSU-E2 was able to invade channel catfish by the immersion route and persist in internal organs for at least 48 h. Channel catfish that were vaccinated with a single immersion dose of LSU-E2 had mortality significantly lower (P < 0.01) following a wild-type E. ictaluri challenge than that of nonvaccinated fish.


Subject(s)
Bacterial Vaccines/immunology , Enterobacteriaceae/immunology , Ictaluridae/microbiology , Animals , Base Sequence , Molecular Sequence Data , Mutation , Polymerase Chain Reaction , Vaccines, Attenuated/immunology
4.
Dev Biol Stand ; 90: 125-34, 1997.
Article in English | MEDLINE | ID: mdl-9270841

ABSTRACT

Enteric septicaemia of catfish (ESC), caused by Edwardsiella ictaluri, is the most serious disease affecting commercial catfish culture in the United States. ESC is generally an acute septicaemia that develops very quickly, especially in the temperature range of 22-28 degrees C, with a more chronic disease presentation outside this range. The ability of E. ictaluri to avoid the host's immune system and proliferate into a systemic infection is impressive. Catfish kidney tissue cultured positive for E. ictaluri as soon as 15 minutes following gastric lavage and signs of disease are observed microscopically within two days of immersion challenge, with reported mortalities as early as five days following immersion challenge. Analysis of E. ictaluri antigens by several investigators using SDS-PAGE and colorimetric western blotting with immune catfish has identified as many as 15 immunogenic bands. Analysis using two-dimensional SDS-PAGE and chemiluminescent western blotting identified 14 bands and 25 spots as consistently immunogenic. The strongest immunodominant antigens were reported as 34-37 KD and 60 KD, depending on the study. Lipopolysaccharide is the only purified component of E. ictaluri tested for fish vaccination, and results indicated that very poor protection was induced unless Freund's Complete Adjuvant was used. Because E. ictaluri strains are serologically homogeneous, most studies on vaccination have emphasized killed whole cell preparations and have delivered equivocal results. Although antibodies are produced to a variety of preparations, a positive antibody response does not correlate with protection unless very high titres are achieved. Efficacy of killed products has been demonstrated in field trials, and an orally delivered product has been licensed. However, protection probably relies on booster exposure of the host to E. ictaluri during non-permissive temperatures. As a facultative intracellular pathogen, further studies on vaccination of catfish against E. ictaluri should target products and delivery methods that favour induction of cell mediated immunity.


Subject(s)
Antigens, Bacterial/pharmacology , Fish Diseases/prevention & control , Gram-Negative Bacteria/immunology , Gram-Negative Bacterial Infections/veterinary , Immunization/veterinary , Sepsis/veterinary , Animals , Antibodies, Bacterial/biosynthesis , Antigens, Bacterial/isolation & purification , Bacterial Vaccines/pharmacology , Fish Diseases/immunology , Gram-Negative Bacteria/pathogenicity , Gram-Negative Bacterial Infections/immunology , Gram-Negative Bacterial Infections/prevention & control , Ictaluridae , Immunity, Cellular , Sepsis/immunology , Sepsis/prevention & control , Vaccination/veterinary , Virulence
5.
Appl Environ Microbiol ; 62(3): 848-52, 1996 Mar.
Article in English | MEDLINE | ID: mdl-16535274

ABSTRACT

In this report, a complete defined medium and a minimally defined medium are described for Edwardsiella ictaluri. The complete defined medium consists of 46 individual components, including a basal salt solution, glucose, magnesium sulfate, iron sulfate, six trace metals, four nucleotides, 10 vitamins, and 19 amino acids. This medium supports growth in broth and on solid media. Optimal growth at 30(deg)C was obtained at pH 7.0, and at an osmolality of 390 mosmol/kg of H(inf2)O, with a glucose concentration of 4 g/liter. The defined minimal medium reduces the 46 components of the complete medium to eight essential components, including the basal salt solution, glucose, magnesium sulfate, pantothenic acid, and niacinamide. In addition, specific amino acids that depend on the specific requirements of the individual strains of E. ictaluri are added.

6.
J Vet Pharmacol Ther ; 18(4): 306-10, 1995 Aug.
Article in English | MEDLINE | ID: mdl-8583544

ABSTRACT

Channel catfish (n = 84) maintained at a water temperature of 27 degrees C were used in a feeding study to determine the plasma to muscle concentration ratios of sulfadimethoxine (SDM) and 4-N-acetylsulfadimethoxine residues. Sulfadimethoxine medicated feed was provided free choice at 42 mg SDM/kg body weight once daily for 5 days and the plasma and muscle concentrations of SDM were determined at selected withdrawal times (6, 12, 24, 48, 72, and 96 hours) following the last dose. Considerable variation in total SDM tissue concentration among fish within a sampling period was observed. For fish (n = 12) at six hours post-dose, total SDM concentrations ranged from 1.4-24.8 micrograms/mL and 0.6-12.6 micrograms/g, with mean total SDM concentrations of 9.1 micrograms/mL and 5.3 micrograms/g for plasma and muscle, respectively. However, a mean plasma:muscle concentration ratio of 1.8:1 +/- 0.3:1 was obtained over all concentrations and sampling periods. The plasma:muscle 95% t distribution interval for individual fish was 1.2:1 to 2.4:1. A correlation coefficient of 0.967 was obtained for the relationship between plasma and muscle total SDM concentration among individual fish (n = 25). Results of this study indicate that plasma total SDM concentration may be used to identify samples containing violative SDM muscle residue. No fish contained total SDM muscle residues greater than the FDA tolerance (0.1 microgram/g) by 48 hours following the final dose.


Subject(s)
Anti-Infective Agents/pharmacokinetics , Drug Residues/pharmacokinetics , Ictaluridae/metabolism , Muscles/metabolism , Sulfadimethoxine/pharmacokinetics , Animals , Anti-Infective Agents/blood , Aquaculture , Chromatography, High Pressure Liquid , Female , Male , Sulfadimethoxine/analogs & derivatives , Sulfadimethoxine/blood
7.
Virology ; 202(2): 659-64, 1994 Aug 01.
Article in English | MEDLINE | ID: mdl-8030231

ABSTRACT

The channel catfish herpesvirus (CCV) thymidine kinase (TK) gene was mapped on the CCV genome by marker rescue analysis using a TK-deficient channel catfish ovary cell line (CCO), a TK-negative CCV mutant, and a panel of cloned CCV genomic DNA fragments. The TK-deficient cell line (CCOBr) was isolated after repeated propagation of CCO cells in increasing concentrations of 5-bromo-2'-deoxyuridine. Infection of CCOBr cells with CCV produced high levels of TK activity. The TK- virus (CCVAr) was isolated after repeated propagation in the presence of the TK-activated antiherpetic agent, 1-beta-D-arabinofuranosylthymine (Ara-T). A CCV genomic DNA library was constructed into cosmid pHC 79. Marker rescue analysis mapped the mutation within a 3.1-kb fragment located internal to the 18-kb repeat ends of the CCV genome. These genomic coordinates contained a putative TK gene identified by homology to other herpesvirus TK and cellular deoxycytidine kinase genes. DNA sequencing of the mapped coordinates identified the presence of a single mutation in the CCVAr mutant virus which resulted in a stop codon at amino acid position 97. These results functionally confirm that ORF 5 identified by Davison (Virology 186, 9-14, 1992) is the TK gene and show that CCV is amenable to marker rescue and marker transfer genetic analyses extensively used for investigations of the molecular biology of other herpesviruses.


Subject(s)
Herpesviridae/enzymology , Ictaluridae/microbiology , Thymidine Kinase/genetics , Animals , Arabinonucleosides/pharmacology , Cell Line , Cloning, Molecular , Drug Resistance, Microbial , Genes, Viral , Herpesviridae/genetics , Molecular Sequence Data , Mutation , Repetitive Sequences, Nucleic Acid , Thymidine/analogs & derivatives , Thymidine/pharmacology , Transfection , Viral Structural Proteins/genetics
8.
J Wildl Dis ; 27(4): 557-61, 1991 Oct.
Article in English | MEDLINE | ID: mdl-1758021

ABSTRACT

Motile aeromonads are ubiquitous aquatic bacteria that can cause motile aeromonad septicemia (MAS), a disease which affects channel catfish and can produce significant economic loss. Motile aeromonads isolated from commercially-raised channel catfish were screened for production of S-layer protein in order to evaluate its potential role in natural epizootics. The S-layer protein was produced by 14 of 24 (58%) isolates from epizootics evaluated in this study. Concomitant infections with other internal pathogens were detected in 10 of the 24 cases used in this study, and only one of those 10 isolates (10%) produced the S-layer protein. When Aeromonas sp. was the only internal pathogen diagnosed, 13 of 14 (93%) isolates produced the S-layer protein.


Subject(s)
Aeromonas/chemistry , Bacterial Outer Membrane Proteins/biosynthesis , Fish Diseases/microbiology , Gram-Negative Bacterial Infections/veterinary , Ictaluridae , Aeromonas/metabolism , Animals , Bacterial Outer Membrane Proteins/analysis , Disease Outbreaks/veterinary , Electrophoresis, Polyacrylamide Gel , Fish Diseases/epidemiology , Fisheries , Gram-Negative Bacterial Infections/epidemiology , Gram-Negative Bacterial Infections/microbiology
10.
Appl Environ Microbiol ; 48(2): 456-8, 1984 Aug.
Article in English | MEDLINE | ID: mdl-6385854

ABSTRACT

Three protease-containing fractions were recovered by gel filtration from concentrated crude extracellular products produced by Aeromonas hydrophila grown in a defined medium. The recovery of a heat-stable protease was differentially prevented when the crude preparation was stored for 48 h at -20 degrees C but was unaffected by storage of the crude preparation at either 4 or -70 degrees C. Once fractionated, the heat-stable protease appeared to be unaffected by subsequent storage at 4, -20, or -70 degrees C.


Subject(s)
Aeromonas/enzymology , Peptide Hydrolases/isolation & purification , Drug Stability , Electrophoresis, Polyacrylamide Gel , Hot Temperature , Kinetics , Molecular Weight , Peptide Hydrolases/metabolism
11.
J Wildl Dis ; 19(3): 180-4, 1983 Jul.
Article in English | MEDLINE | ID: mdl-6358536

ABSTRACT

A systemic streptococcal infection in cultured bullfrogs in Brazil was characterized by necrotizing splenitis and hepatitis with hepatic and renal hemorrhage. A non-hemolytic Group B Streptococcus appeared to be the cause of the lesions, and the stimulus for the splenic reticuloendothelial hyperplasia observed in the animals. Stress may have been a factor in the development of the pathological condition.


Subject(s)
Rana catesbeiana , Streptococcal Infections/veterinary , Animals , Brazil , Kidney/pathology , Liver/pathology , Spleen/pathology , Streptococcal Infections/pathology , Streptococcus agalactiae
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