Experimental Pseudomonas anguilliseptica infection in turbot Psetta maxima (L.): a histopathological and immunohistochemical study

Experimental infection with Pseudomonas anguilliseptica was performed both by intraperitoneal (i.p.) and bath route on juvenile turbot (Psetta maxima) in order to evaluate the pathology induced. Turbot was found to be sensitive to i.p. challenge (1.7×106 CFU/fish) but no to bath exposure. The i.p. challenge induced septicaemic infection and mortality. Externally, moribund fish showed distended abdomen and pale areas at day 9. The gross pathological internal signs present were abundant ascitic fluid in the peritoneal cavity, pale and enlarged spleen, pale and friable liver, and congestive and dilated gut with yellowish exudates. On histopathological examination, bacterial invasion was common in all the tissues studied but the most prominent pathological changes were observed in gut, spleen and kidney after 7 day with features of necrosis. The immunohistochemical findings support the widespread localization of the bacteria after the i.p. injection since the P. anguilliseptica was detected in spleen from day 1 post injection, in liver, kidney and gut from day 4, in muscle from day 7 and in brain from day 9. The difficulties in infecting healthy fish by bath challenge can be explained by the opportunistic nature of this pathogen

Global market: shellfish imports as a source of reemerging food-borne hepatitis A virus infections in Spain

A total of 16 mollusk imports from South America to Spain, including clam and scallop species, were analyzed for hepatitis A virus (HAV), due to the great concern about this type of food after an important hepatitis A outbreak in eastern Spain in September 1999. In addition, clams from the stock that had caused the outbreak were also tested. Of the 17 stocks, four were positive for the presence of HAV RNA as demonstrated by RT-PCR and Southern hybridization. Contradictory analyses confirmed the results of the primary tests in all cases. The findings obtained in this work strongly support the role of mollusk imports from endemic areas of HAV as an important vehicle of hepatitis A, and demonstrate the imperative need for sanitary control measures to prevent future outbreaks of this disease

Two-dimensional proteome reference map of Vibrio tapetis, the aetiological agent of brown ring disease in clams

Aims: Vibrio tapetis is the etiological agent of brown ring disease (BRD) in clams, one of the most threatening diseases affecting this commercially important bivalve. In this study we have constructed a proteome reference map of the V. tapetis type strain CECT 4600T. Methods and Results: Eighty-two proteins, consistently present in all 2D-gels, were identified by mass spectrometry or by de novo sequencing. The majority of the proteins identified (66%) belonged to four COG categories: 'Carbohydrate transport and metabolism', 'Post-translational modification, protein turnover and chaperones', 'Energy production', and 'Amino acid transport and metabolism'. Glyceraldehyde-3-phosphate dehydrogenase, enolase, fructose-bisphosphate aldolase, phosphoglycerate kinase. molecular chaperones Dnak and GroEL, alkyl hydroperoxide reductase, peptidyl-prolyl cis-trans isomerase B and factor Tu, were identified among the 20 most abundant proteins. A comparison of this reference map with that obtained for the V. tapetis strain GR0202RD, with different origin and pathophysiological characteristics, was performed. Conclusions: Under the culture conditions employed in this study, glucose degradation is one of the major pathways for energy production in Vibrio tapetis. In addition, the two strains studied, although with remarkable differences at genetic and pathophysiological levels, showed a high similarity under laboratory conditions. Significance and Impact of the Study: The results obtained here can be considered as a first step to gather valuable information on protein expression, related not only to diverse cellular functions and regulation but also to pathogenesis and bacterium-host interactions in the disease process

Comparative Genomic Analysis of Two Vibrio toranzoniae Strains with Different Virulence Capacity Reveals Clues on Its Pathogenicity for Fish

Vibrio toranzoniae is a Gram-negative bacterium of the Splendidus clade within the Vibrio genus. V. toranzoniae was first isolated from healthy clams in Galicia (Spain) but recently was also identified associated to disease outbreaks of red conger eel in Chile. Experimental challenges showed that the Chilean isolates were able to produce fish mortalities but not the strains isolated from clams. The aim of the present study was to determine the differences at the genomic level between the type strain of the species (CECT 7225T) and the strain R17, isolated from red conger eel in Chile, which could explain their different virulent capacity. The genome-based comparison showed high homology between both strains but differences were observed in certain gene clusters that include some virulence factors. Among these, we found that iron acquisition systems and capsule synthesis genes were the main differential features between both genomes that could explain the differences in the pathogenicity of the strains. Besides, the studied genomes presented genomic islands and toxins, and the R17 strain presented CRISPR sequences that are absent on the type strain. Taken together, this analysis provided important insights into virulence factors of V. toranzoniae that will lead to a better understanding of the pathogenic processThis research was supported in part by grants AGL2013-42628R and AGL2016-77539R from Ministerio de Economia y Competitividad (Spain)S

<i>Vibrio breoganii</i> sp. nov., a non-motile, alginolytic, marine bacterium within the <i>Vibrio halioticoli</i> clade

Seven non-motile, facultatively anaerobic, alginolytic marine bacteria were isolated from the cultured clams Ruditapes philippinarum and Ruditapes decussatus. Phylogenetic analysis based on 16S rRNA gene sequences showed that these marine bacteria were closely related to the recently described species Vibrio comitans, Vibrio rarus and Vibrio inusitatus (=99.0?% sequence similarity). Phylogenetic analysis based on the housekeeping genes rpoA, recA and atpA grouped the isolates together and allocated them to the Vibrio halioticoli species group. Amplified fragment length polymorphism DNA fingerprinting also grouped them together and enabled them to be differentiated from recognized species of the V. halioticoli clade. DNA–DNA hybridizations showed that the isolates belonged to a novel species; phenotypic features such as the ability to grow at 4 °C and in the presence of 6?% NaCl also enabled them to be separated from other species. The DNA G+C content of RD 15.11T is 44.4 mol%. The genotypic and phenotypic data showed that the isolates represent a novel species in the V. halioticoli clade. The name Vibrio breoganii sp. nov. is proposed, with RD 15.11T (=CECT 7222T =LMG 23858T) as the type strain

Draft Genome Sequence of the New Pathogen for Bivalve Larvae \u3cem\u3eVibrio bivalvicida\u3c/em\u3e

Vibrio bivalvicida is a novel pathogen of bivalve larvae responsible for recent vibriosis outbreaks affecting shellfish hatcheries. Here, we announce the draft genome sequence of V. bivalvicida 605 and describe potential virulence factors

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

Revisiting the Taxonomy of the Genus Arcobacter: Getting Order From the Chaos

Since the description of the genus Arcobacter in 1991, a total of 27 species have been described, although some species have shown 16S rRNA similarities below 95%, which is the cut-off that usually separates species that belong to different genera. The objective of the present study was to reassess the taxonomy of the genus Arcobacter using information derived from the core genome (286 genes), a Multilocus Sequence Analysis (MLSA) with 13 housekeeping genes, as well as different genomic indexes like Average Nucleotide Identity (ANI), in silico DNA–DNA hybridization (isDDH), Average Amino-acid Identity (AAI), Percentage of Conserved Proteins (POCPs), and Relative Synonymous Codon Usage (RSCU). The study included a total of 39 strains that represent all the 27 species included in the genus Arcobacter together with 13 strains that are potentially new species, and the analysis of 57 genomes. The different phylogenetic analyses showed that the Arcobacter species grouped into four clusters. In addition, A. lekithochrous and the candidatus species ‘A. aquaticus’ appeared, as did A. nitrofigilis, the type species of the genus, in separate branches. Furthermore, the genomic indices ANI and isDDH not only confirmed that all the species were well-defined, but also the coherence of the clusters. The AAI and POCP values showed intra-cluster ranges above the respective cut-off values of 60% and 50% described for species belonging to the same genus. Phenotypic analysis showed that certain test combinations could allow the differentiation of the four clusters and the three orphan species established by the phylogenetic and genomic analyses. The origin of the strains showed that each of the clusters embraced species recovered from a common or related environment. The results obtained enable the division of the current genus Arcobacter in at least seven different genera, for which the names Arcobacter, Aliiarcobacter gen. nov., Pseudoarcobacter gen. nov., Haloarcobacter gen. nov., Malacobacter gen. nov., Poseidonibacter gen. nov., and Candidate ‘Arcomarinus’ gen. nov. are proposedThis work was supported in part by Grants JPIW2013-69095-C03-03 from the Ministerio de Economía y Competitividad (MINECO), AQUAVALENS of the Seventh Framework Program (FP7/2007-2013) grant agreement 311846 from the European Union and AGL2013-42628-R and AGL2016-77539-R (AEI/FEDER UE) from the Agencia Estatal de Investigación (Spain)S