Characterization of a birnavirus isolated from diseased turbot cultured in Spain

7 pages, 5 figures, 2 tables.During 1989, light but persistent mortalities were detected in a turbot Scophthalmus maximus L. farm in Galicia (northwestern Spain) and a virus with the characteristics of a birnavirus was isolated. The purpose of this study was to characterize the viral agent and determine the susceptibility of turbot to this virus. Electron microscopic examination revealed that the particles were isometric, hexagonal and unenveloped with an average diameter of 58 to 60 nm. The molecular weights of the RNA segments were 1.9 and 2.0 x 10(up to 6) daltons. The cells most susceptible to the turbot isolate were the CHSE-214, FHM and RTG-2 lines and the optimal temperature range for its replication was 15 to 2OºC. The RNA and polypeptide electropherotypes show that this virus resembles the Ab serotype of infectious pancreatic necrosis virus (IPNV); however, it differs in that it replicates in the FHM cell line and is not neutralized by antisera to the classical serotypes of IPNV. Infectivity trials conducted in turbot of dlfferent sizes indicated that the virus produced mortality only in small fish (2 g), although the larger fish (30 g) harbored the virus for at least 35 d. Fish inoculated with this isolate showed no pancreatic necrosis although necrosis of the hematopoietic elements of the kidney and spleen was detected.This work was supported by Grants MAR 89-0270 from the Comision Interministenal de Ciencia y Tecnologia (CICYT), and by XUGA 70708888 from Xunta de Galicia, Spain. Beatriz Novoa acknowledges the Ministerio de Educacion y Ciencia (Spain) for a research fellowship.Peer reviewe

Microflora associated with healthy and diseased turbot (Scophthalmus maximus) from three farms in northwest Spain

14 páginas, 4 tablas, 3 figurasA comparative analysis of the microbiological quality of three turbot (Scophthabnus maximus) farms (A, B, and C) located in Galicia (northwest Spain) is given. The microbial load and types of bacteria in the internal organs (liver and kidney) of apparently healthy fish was monitored over a year, and all the disease problems occurring during this survey were analyzed. The percentage of healthy turbot in which positive bacterial growth was obtained was relatively high in the three ongrowing facilities. Farm A exhibited the poorest conditions of fish health with an average of 42% fish infected, while farm B showed the best microbiological quality with 27% of turbot harbouring bacteria in the internal organs. In all three farms, a wide range of bacteria was found in healthy turbot with Vibrio ( V. splendidus-V pelagius, Vjisheri-V harveyi and Vibrio spp.) and Pseudomonas spp. being the predominant groups comprising at least 80% of the total bacterial isolates in each farm. The highest number of pathological problems (22 ) with the most diverse bacterial flora occurred in farm A. Vibrio spp. and Pseudomonas spp. were the most prevalent bacteria recovered from diseased turbot. Haemorrhages in palate and jaws, tail and fins, and ulcerative lesions were the most frequent external clinical signs of diseased fish recorded in the three farms. However, it was not possible to associate a particular bacterial species with a specific pathology. Routine use in farm A of oxolinic acid and nitrofurantoin may have led to the development in the Vibrio strains of resistances to both chemotherapeutants (up to 25%).This study was supported by Grants MAR 9 l- 1133~CO2-0 1 and MAR 89- 0270 from the Comision Interministerial de Ciencia y Tecnologia (CICYT), XUGA 8030389 from Xunta de Galicia (Spain), and EUREKA project No. EU-347, between Spain and Norway.Peer reviewe

Flexibatteriosi da Tenacibaculum maritimum sierotipo O3 in pesce capone (Chelidonichthys lucerna L.) d’allevamento: prima segnalazione in Italia. First report of Tenacibaculum maritimum serotype O3 infecton in cultured tub gurnard (Chelidonichthys lucerna) in Italy.

The present study describes the first isolation of Tenacibaculum maritimum from tub gurnard (Chelidonichthys lucernus L.), cultured in Italy. After 3 days shipment from one fish farm to our laboratory facilities, a group of 20 tub gurnard showed eroded mouth, rotten fins and severe skin ulcerative lesions. Mortality reached 90% of the population in 9 days. Traditional bacteriological and PCR analysis allowed the identification of the causative agent as T. maritimum. Serological characterization of the isolate demonstrated that it belongs to serotype O3. Histopathological examination showed severe skin necrosis, dermis congestion associated with eterophilic and macrophagic infiltration. Immunohistochemical analysis, using specific polyclonal antiserum against T. maritimum serotype O3, allowed the visualization of numerous positively stained macrophagic cells. The high mortality observed during the outbreak leads to consider the T. maritimum as a potential risk for the culture of tub gurnard

Benznidazole biotransformation and multiple targets in <i>Trypanosoma</i> cruzi revealed by metabolomics

&lt;b&gt;Background&lt;/b&gt;&lt;p&gt;&lt;/p&gt; The first line treatment for Chagas disease, a neglected tropical disease caused by the protozoan parasite Trypanosoma cruzi, involves administration of benznidazole (Bzn). Bzn is a 2-nitroimidazole pro-drug which requires nitroreduction to become active, although its mode of action is not fully understood. In the present work we used a non-targeted MS-based metabolomics approach to study the metabolic response of T. cruzi to Bzn.&lt;p&gt;&lt;/p&gt; &lt;b&gt;Methodology/Principal findings&lt;/b&gt;&lt;p&gt;&lt;/p&gt; Parasites treated with Bzn were minimally altered compared to untreated trypanosomes, although the redox active thiols trypanothione, homotrypanothione and cysteine were significantly diminished in abundance post-treatment. In addition, multiple Bzn-derived metabolites were detected after treatment. These metabolites included reduction products, fragments and covalent adducts of reduced Bzn linked to each of the major low molecular weight thiols: trypanothione, glutathione, γ-glutamylcysteine, glutathionylspermidine, cysteine and ovothiol A. Bzn products known to be generated in vitro by the unusual trypanosomal nitroreductase, TcNTRI, were found within the parasites, but low molecular weight adducts of glyoxal, a proposed toxic end-product of NTRI Bzn metabolism, were not detected.&lt;p&gt;&lt;/p&gt; &lt;b&gt;Conclusions/significance&lt;/b&gt;&lt;p&gt;&lt;/p&gt; Our data is indicative of a major role of the thiol binding capacity of Bzn reduction products in the mechanism of Bzn toxicity against T. cruzi

Photodynamic Antimicrobial Chemotherapy in Aquaculture: Photoinactivation Studies of Vibrio fischeri

BACKGROUND: Photodynamic antimicrobial chemotherapy (PACT) combines light, a light-absorbing molecule that initiates a photochemical or photophysical reaction, and oxygen. The combined action of these three components originates reactive oxygen species that lead to microorganisms' destruction. The aim was to evaluate the efficiency of PACT on Vibrio fischeri: 1) with buffer solution, varying temperature, pH, salinity and oxygen concentration values; 2) with aquaculture water, to reproduce photoinactivation (PI) conditions in situ. METHODOLOGY/PRINCIPAL FINDINGS: To monitor the PI kinetics, the bioluminescence of V. fischeri was measured during the experiments. A tricationic meso-substituted porphyrin (Tri-Py(+)-Me-PF) was used as photosensitizer (5 µM in the studies with buffer solution and 10-50 µM in the studies with aquaculture water); artificial white light (4 mW cm(-2)) and solar irradiation (40 mW cm(-2)) were used as light sources; and the bacterial concentration used for all experiments was ≈10(7) CFU mL(-1) (corresponding to a bioluminescence level of 10(5) relative light units--RLU). The variations in pH (6.5-8.5), temperature (10-25°C), salinity (20-40 g L(-1)) and oxygen concentration did not significantly affect the PI of V. fischeri, once in all tested conditions the bioluminescent signal decreased to the detection limit of the method (≈7 log reduction). The assays using aquaculture water showed that the efficiency of the process is affected by the suspended matter. Total PI of V. fischeri in aquaculture water was achieved under solar light in the presence of 20 µM of Tri-Py(+)-Me-PF. CONCLUSIONS/SIGNIFICANCE: If PACT is to be used in environmental applications, the matrix containing target microbial communities should be previously characterized in order to establish an efficient protocol having into account the photosensitizer concentration, the light source and the total light dose delivered. The possibility of using solar light in PACT to treat aquaculture water makes this technology cost-effective and attractive

Phage therapy as an approach to prevent Vibrio anguillarum infections in fish larvae production

Fish larvae in aquaculture have high mortality rates due to pathogenic bacteria, especially the Vibrio species, and ineffective prophylactic strategies. Vaccination is not feasible in larvae and antibiotics have reduced efficacy against multidrug resistant bacteria. A novel approach to controlling Vibrio infections in aquaculture is needed. The potential of phage therapy to combat vibriosis in fish larvae production has not yet been examined. We describe the isolation and characterization of two bacteriophages capable of infecting pathogenic Vibrio and their application to prevent bacterial infection in fish larvae. Two groups of zebrafish larvae were infected with V. anguillarum (∼106 CFU mL-1) and one was later treated with a phage lysate (∼108 PFU mL-1). A third group was only added with phages. A fourth group received neither bacteria nor phages (fish control). Larvae mortality, after 72 h, in the infected and treated group was similar to normal levels and significantly lower than that of the infected but not treated group, indicating that phage treatment was effective. Thus, directly supplying phages to the culture water could be an effective and inexpensive approach toward reducing the negative impact of vibriosis in larviculture