| piscirickettsia salmonis gen. nov., sp. nov., the causative agent of an epizootic disease in salmonid fishes. | a novel intracellular pathogen morphologically similar to the ehrlichiae has been isolated in cell culture and identified as the cause of an epizootic disease of salmonid fish. like the ehrlichiae, the salmonid pathogen, designated strain lf-89, replicates within membrane-bound cytoplasmic vacuoles in host cells. this agent is the first with characteristics of this type to be isolated from a fish. analysis of the lf-89 16s rrna indicated that, unlike the ehrlichiae, lf-89 is a gamma proteobacter ... | 1992 | 1371057 |
| antigenic characterization of the salmonid pathogen piscirickettsia salmonis. | piscirickettsia salmonis, the etiological agent of salmonid rickettsial septicemia, was purified from infected immortal chinook salmon (oncorhynchus tshawytscha) embryo cells by a combination of differential and percoll density gradient centrifugation. immune sera from rabbits immunized with purified whole cells of p. salmonis reacted with four protein antigens and two carbohydrate antigens with relative molecular sizes of 65, 60, 54, 51, 16, and approximately 11 kda, respectively. the carbohydr ... | 1996 | 8945567 |
| in vitro infection of a cell line from ictalurus nebulosus with piscirickettsia salmonis. | piscirickettsia salmonis, the etiologic agent of salmonid rickettsial septicemia (srs), affects several species of salmonids. previous reports using the appearance of cytopathic effect (cpe) as the criterion for susceptibility, showed that piscirickettsia salmonis (atcc strain) can be grown in vitro in some cells lines derived from salmonid fish, but not in bb cells from brown bullhead (ictalurus nebulosus) and bf-2 cells from bluegill (lepomis macrochirus). in this study we describe growth of p ... | 1997 | 9008805 |
| the rickettsia: an emerging group of pathogens in fish. | piscirickettsia salmonis is the first of the previously unrecognized rickettsial pathogens of fish to be fully characterized. since the recognition of p. salmonis in 1989, the impact of rickettsial pathogens in fish has become increasingly apparent. growing awareness of the emergence of these fastidious intracellular organisms has led to the discovery of rickettsial diseases among diverse species of fish from different geographic locations and aquatic environments. the source, reservoir, and mod ... | 1997 | 9204294 |
| immunization with bacterial antigens: piscirickettsiosis. | piscirickettsiosis is a septicaemic disease of salmonid fish caused by the obligated intracellular rickettsia, piscirickettsia salmonis. this disease was first reported in 1989 in salmon cultured in sea water netpens in southern chile where it is still a major problem causing high mortality among cultured salmonids. in recent years related agents have been reported in farmed salmonids from ireland, canada and norway. mortality, however, at these locations has been reported to be low. because of ... | 1997 | 9270845 |
| virulence and antigenic characteristics of a cultured rickettsiales-like organism isolated from farmed atlantic salmon salmo salar in eastern canada. | the present study describes culture, virulence and antigenic characteristics of a rickettsiales-like organism (rlo) associated with mortality in farmed atlantic salmon in eastern canada. clinical disease was reproduced in naive atlantic salmon parr by intraperitoneal i.p. inoculation with kidney homogenate from naturally infected fish. pure cultures of rlo were isolated into chinook salmon embryo (chse) cells from kidney of experimentally infected fish. the rlo caused cytopathic effect in cultur ... | 1998 | 9653456 |
| purification of piscirickettsia salmonis and partial characterization of antigens. | piscirickettsia salmonis is the etiological agent of salmonid rickettsial septicemia, an economically significant disease affecting the salmon aquaculture industry. as with other rickettsial pathogens, antigenic analysis of p. salmonis has been limited by the inherent difficulties of purifying an intracellular organism away from host cell material. in this report, we describe the use of diatrizoate meglumine and diatrizoate sodium (dmds) density gradient centrifugation to purify p. salmonis grow ... | 1998 | 9678968 |
| minimally invasive detection of piscirickettsia salmonis in cultivated salmonids via the pcr. | the attributes of the pcr allowed implementation of an assay for specific detection of piscirickettsia salmonis from a few microliters of fish serum. this opens the way to less invasive modes of sampling for this microbial pathogen in salmonids. | 1998 | 9687475 |
| relative virulence of three isolates of piscirickettsia salmonis for coho salmon oncorhynchus kisutch. | piscirickettsia salmonis was first recognized as the cause of mortality among pen-reared coho salmon oncorhynchus kisutch in chile. since the initial isolation of this intracellular gram-negative bacterium in 1989, similar organisms have been described from several areas of the world, but the associated outbreaks were not reported to be as serious as those that occurred in chile. to determine if this was due to differences in virulence among isolates of p. salmonis, we conducted an experiment co ... | 1999 | 10092973 |
| phylogenetic analysis of piscirickettsia salmonis by 16s, internal transcribed spacer (its) and 23s ribosomal dna sequencing. | piscirickettsia salmonis, the etiologic agent of piscirickettsiosis, is a systemic disease of salmonid fish. variations in virulence and mortality have been observed during epizootics at different geographical regions and in laboratory experiments with isolates from these different locations. this raises the possibility that biogeographical patterns of genetic variation might be a significant factor with this disease. to assess the genetic variability the 16s ribosomal dna, the internal transcri ... | 1999 | 10092974 |
| routes of entry of piscirickettsia salmonis in rainbow trout oncorhynchus mykiss. | since 1989, piscirickettsia salmonis, the causal agent of piscirickettsiosis, has killed millions of farmed salmonids each year in southern chile. the portal of entry for the pathogen was investigated by use of selected experimental infections in juvenile rainbow trout (12 g). the methods used were intraperitoneal injection, subcutaneous injection, patch contact on skin, patch contact on gills, intestinal intubation and gastric intubation. cumulative mortalities at day 33 post-inoculation were 9 ... | 1999 | 10546046 |
| monitoring piscirickettsia salmonis by denaturant gel electrophoresis and competitive pcr. | reported strains of piscirickettsia salmonis, a pathogen of salmonid fishes, were analyzed by amplifying part of the internal transcribed spacer (its) of the ribosomal rna (rrna) operon followed by denaturing gradient gel electrophoresis (dgge) of the amplicons. all amplified fragments differing in sequence were distinguished by migration during dgge. a simpler format, constant denaturant gel electrophoresis (cdge), allowed the same diagnostic distinctions among strains. sampling during 1997 and ... | 2000 | 10907135 |
| pathogenesis of liver lesions caused by experimental infection with piscirickettsia salmonis in juvenile atlantic salmon, salmo salar l. | piscirickettsia salmonis, the etiologic agent of salmonid rickettsial septicemia (srs), or piscirickettsiosis, causes substantial economic losses to the salmon industry. the pathogenesis of the disease has not been fully characterized. the aim of this study is to describe the hepatic lesions associated with experimental p. salmonis infection in atlantic salmon juveniles. fish were maintained in fresh water and inoculated intraperitoneally (ip), orally, or on the gill surface with p. salmonis. a ... | 2000 | 11108456 |
| a piscirickettsia salmonis-like bacterium associated with mortality of white seabass atractoscion nobilis. | mortality among hatchery-reared juvenile white seabass atractoscion nobilis in southern california, usa, was associated with infections by a piscirickettsia salmonis-like organism (wspslo). infected fish had no consistent external signs other than pale gills, lethargy and impaired swimming behavior. internally, the kidney and spleen were enlarged, and some fish had livers with multiple pale foci. smears from infected kidney, liver, and spleen stained with wright-giemsa had intracytoplasmic cocco ... | 2000 | 11145452 |
| ospa, a lipoprotein antigen of the obligate intracellular bacterial pathogen piscirickettsia salmonis. | no effective recombinant vaccines are currently available for any rickettsial diseases. in this regard the first non-ribosomal dna sequences from the obligate intracellular pathogen piscirickettsia salmonis are presented. genomic dna isolated from percoll density gradient purified p. salmonis, was used to construct an expression library in lambda zap ii. in the absence of preexisting dna sequence, rabbit polyclonal antiserum raised against p. salmonis, with a bias toward p. salmonis surface anti ... | 2001 | 11200233 |
| an efficacious recombinant subunit vaccine against the salmonid rickettsial pathogen piscirickettsia salmonis. | piscirickettsia salmonis is the aetiological agent of salmonid rickettsial septicaemia, an economically devastating rickettsial disease of farmed salmonids. infected salmonids respond poorly to antibiotic treatment and no effective vaccine is available for the control of p. salmonis. bacterin preparations of p. salmonis were found to elicit a dose-dependent response in coho salmon (oncorhynchus kisutch), which varied from inadequate protection to exacerbation of the disease. however, an outer su ... | 2001 | 11257358 |
| trna genes were found in piscirickettsia salmonis 16s-23s rdna spacer region (its). | piscirickettsia salmonis is the etiological agent of salmonid rickettsial septicemia, a disease affecting salmon aquaculture industry. we analyzed the 16s-23s rdna spacer region (internal transcribed spacer, its) of chilean p. salmonis isolates lf-89 and em-90. two main its amplification products were obtained by pcr using l1 and g1 primers, differing from that described where only one its region was found. by southern blot, it was established that these two amplification products contained sequ ... | 2001 | 11287140 |
| purification of piscirickettsia salmonis and associated phage particles. | piscirickettsia salmonis was isolated from cell culture using differential centrifugation and purified on a 30% percol gradient. the purity of the preparation was assessed by transmission electron microscopy and phage-like particles were found to be associated with some of the p. salmonis isolates examined. this is believed to be the first report of a phage associated with rickettsia from fish. | 2001 | 11383571 |
| piscirickettsiosis and piscirickettsiosis-like infections in fish: a review. | piscirickettsia salmonis was the first "rickettsia-like" bacteria to be recognized as a pathogenic agent of fish. since the first reports of piscirickettsiosis emerged from chile in the late 1980s, piscirickettsia-like bacteria have been recognized with increasing frequency in a variety of fish species, from both fresh and saltwaters around the world. although the first reported incidents of piscirickettsia were in salmonids, piscirickettsia-like bacteria are now being frequently associated with ... | 2002 | 12069766 |
| detection of piscirickettsia salmonis in fish tissues by an enzyme-linked immunosorbent assay using specific monoclonal antibodies. | an enzyme-linked immunosorbent assay (elisa) for the detection of piscirickettsia salmonis in fish tissue samples was developed. the test uses a combination of different monoclonal antibodies specific against p. salmonis in the capture step of the assay. the antibodies 7g4, 6e2 and 2c1 chosen for the capture step are bound to the solid support with an adhesive protein purified from a bivalve mollusc, resulting in a high yield of adsorption and binding stability. the monoclonal antibody 7g4, used ... | 2002 | 12093039 |
| characterization of a piscirickettsiosis-like disease in hawaiian tilapia. | in 1994, tilapia (oreochromis mossambicus and sarotherodon melanotheron) in wild and farmed populations on oahu, hawaii, usa, began to die of an unknown disease that was similar but not identical to piscirickettsiosis in salmonids. only tilapia were affected. diseased tilapia often swam erratically and had trouble staying at depth. scattered cutaneous haemorrhage and exophthalmia were often noted. in many cases, fish were found dead with no clinical signs. gills exhibited epithelial hyperplasia ... | 2003 | 12691196 |
| bacterial diversity in a marine methanol-fed denitrification reactor at the montreal biodome, canada. | the bacterial biota of a methanol-fed denitrification reactor used to treat seawater at the montreal biodome were investigated using culture-dependent and molecular biology methods. the microbiota extracted from the reactor carriers were cultivated on three media. three isolate types were recovered and their 16s ribosomal dna (rdna) genes were determined. the analysis showed that the isolate types were related to alpha-proteobacteria. they are members of the hyphomicrobium and paracoccus genera ... | 2003 | 12739074 |
| electrophoretic analysis of its from piscirickettsia salmonis chilean isolates. | piscirickettsia salmonis is the most important pathogen in salmonid mariculture in chile. since it was reported numerous piscirickettsiosis outbreaks have occurred differing in virulence and mortality. genetic variability of p. salmonis isolates has been suggested as one factor to explain this. however until now isolates obtained from outbreaks have not been analyzed. knowledge of genetic variability of p. salmonis is very limited and also a useful screening method for genetic variations in isol ... | 2003 | 12951237 |
| piscirickettsia salmonis: a gram-negative intracellular bacterial pathogen of fish. | piscirickettsia salmonis is the first gram-negative, intracellular bacterial pathogen isolated from fish and is a significant cause of mortality in salmonid fish. recent reports of p. salmonis or p. salmonis-like organisms from new fish hosts and geographic regions have increased the interest in the bacterium. in this review, the important characteristics of the bacterium including recent taxonomic changes, features of the disease caused by the bacterium including transmission, hosts, reservoirs ... | 2003 | 12962234 |
| experimental vertical transmission of piscirickettsia salmonis and in vitro study of attachment and mode of entrance into the fish ovum. | piscirickettsia salmonis is a pathogenic bacterial agent causing septicaemic disease in salmon. since its isolation in chile in 1989, p. salmonis has continually produced high mortality rates in salmon farms. little information exists regarding the mechanisms of vertical transmission of this pathogen. experimental vertical transmission was established in the present study by inoculation of male and female rainbow trout broodstock with p. salmonis. the bacterium was subsequently detected using in ... | 2003 | 14524498 |
| an alternative efficient procedure for purification of the obligate intracellular fish bacterial pathogen piscirickettsia salmonis. | piscirickettsia salmonis is an obligate intracellular bacterial pathogen of salmonid fish and the etiological agent of the aggressive disease salmonid rickettsial syndrome. today, this disease, also known as piscirickettsiosis, is the cause of high mortality in net pen-reared salmonids in southern chile. although the bacteria can be grown in tissue culture cells, genetic analysis of the organism has been hindered because of the difficulty in obtaining p. salmonis dna free from contaminating host ... | 2003 | 14532090 |
| immunoresponse of coho salmon immunized with a gene expression library from piscirickettsia salmonis. | we have used the expression library immunization technology to study the protection of coho salmon oncorhynchus kisutch to the infection with piscirickettsia salmonis. purified dna from this bacterium was sonicated and the fragments were cloned in the expression vector pcmv-bios. two libraries were obtained containing 22,000 and 28,000 colonies and corresponding to approximately 8 and 10 times the genome of the pathogen, respectively. on average, the size of the inserts ranged between 300 and 1, ... | 2003 | 14631865 |
| cloning and expression of the coding regions of the heat shock proteins hsp10 and hsp16 from piscirickettsia salmonis. | the genes encoding the heat shock proteins hsp10 and hsp16 of the salmon pathogen piscirickettsia salmonis have been isolated and sequenced. the hsp10 coding sequence is located in an open reading frame of 291 base pairs encoding 96 aminoacids. the hsp16 coding region was isolated as a 471 base pair fragment encoding a protein of 156 aminoacids. the deduced aminoacid sequences of both proteins show a significant homology to the respective protein from other prokaryotic organisms. both proteins w ... | 2003 | 14631874 |
| growth of piscirickettsia salmonis to high titers in insect tissue culture cells. | piscirickettsia salmonis was grown in established insect, frog, and fish tissue culture cells. the yield of p. salmonis in sf21 cells was up to 100 times that obtained in chse-214 cells, and virulence for atlantic salmon was retained. the ceiling temperature for growth of p. salmonis in sf21 cells was 24 degrees c. | 2004 | 15155687 |
| dna hybridization assays for the detection of piscirickettsia salmonis in salmonid fish. | | 2004 | 15228613 |
| isolates of piscirickettsia salmonis from scotland and ireland show evidence of clonal diversity. | salmonid rickettsial septicemia, caused by piscirickettsia salmonis, causes major mortalities in chilean salmonid aquaculture and is an increasing problem in atlantic salmon in ireland and scotland. analysis of 16s-to-23s internal transcribed sequences and 16s ribosomal dna (rdna) shows that irish isolates of p. salmonis form two new groups of the organism while scottish isolates cluster together with norwegian and canadian isolates from atlantic salmon. | 2004 | 15240328 |
| microarray analyses identify molecular biomarkers of atlantic salmon macrophage and hematopoietic kidney response to piscirickettsia salmonis infection. | piscirickettsia salmonis is the intracellular bacterium that causes salmonid rickettsial septicemia, an infectious disease that kills millions of farmed fish each year. the mechanisms used by p. salmonis to survive and replicate within host cells are not known. piscirickettsiosis causes severe necrosis of hematopoietic kidney. microarray-based experiments with qpcr validation were used to identify atlantic salmon macrophage and hematopoietic kidney genes differentially transcribed in response to ... | 2004 | 15454580 |
| infectivity of a scottish isolate of piscirickettsia salmonis for atlantic salmon salmo salar and immune response of salmon to this agent. | a scottish isolate of piscirickettsia salmonis (sco-95a), previously shown by intraperitoneal injection to have a lethal dose (ld50) of < 2 x 10(3) infectious rickettsial units, was tested for virulence by bath challenge, surface application to the skin, or dorsal median sinus injection. atlantic salmon salmo salar post-smolts were used in all experiments, and exposure to 1 x 10(5) tissue culture infective doses (tcid) of p. salmonis ml(-1) for 1 h in a bath challenge resulted in only 1 mortalit ... | 2004 | 15460853 |
| experimental infection of coho salmon oncorhynchus kisutch by exposure of skin, gills and intestine with piscirickettsia salmonis. | piscirickettsiosis pathogenesis was examined using some tissues as entry portals of piscirickettsia salmonis in coho salmon. juvenile fish, weighing approximately 8.4 g, were used in this trial. inocula were prepared using the strain slgo-95 of p. salmonis. the micro-organism was cultured in the chse-214 cell line as described by fryer et al. (1990) and doses containing 10(4.7) and 10(3.7) tcid50 were prepared. each dose was used to infect the fish via skin, gills and intestine. skin and gills w ... | 2004 | 15584410 |
| isolation and expression of the genes coding for the membrane bound transglycosylase b (mltb) and the transferrin binding protein b (tbpb) of the salmon pathogen piscirickettsia salmonis. | we have isolated and sequenced the genes encoding the membrane bound transglycosylase b (mltb) and the transferring binding protein b (tbpb) of the salmon pathogen piscirickettsia salmonis. the results of the sequence revealed two open reading frames that encode proteins with calculated molecular weights of 38,830 and 85,140. the deduced aminoacid sequences of both proteins show a significant homology to the respective protein from phylogenetically related microorganisms. partial sequences codin ... | 2004 | 15586827 |
| genetic characterization and experimental pathogenesis of piscirickettsia salmonis isolated from white seabass atractoscion nobilis. | an intracellular bacterium originally isolated from hatchery-reared juvenile white seabass atractoscion nobilis in southern california, usa, was identified by sequences of the small and large subunit ribosomal (16s and 23s) dna and the internal transcribed spacer (its) as piscirickettsia salmonis. considering all rdna sequences compared, the white seabass isolate (wsb-98) had a 96.3 to 98.7% homology with 4 previously described strains of p. salmonis isolated from salmon in chile, norway, and br ... | 2005 | 15819429 |
| characterisation of an emerging rickettsia-like organism in tasmanian farmed atlantic salmon salmo salar. | a rickettsia-like organism (rlo) was observed in farmed atlantic salmon salmo salar located in south-east tasmania, australia. several assays such as immunoperoxidase, immunoelectron microscopy, polymerase chain reaction and nucleic acid sequencing, as well as phylogenetic analysis of rdna sequences, were performed on infected fish tissues. immunohistochemistry results suggested the presence of related antigenic determinants between the tasmanian rlo and the type strain lf-89 of piscirickettsia ... | 2005 | 15900686 |
| confirmation of piscirickettsia salmonis as a pathogen in european sea bass dicentrarchus labrax and phylogenetic comparison with salmonid strains. | european sea bass dicentrarchus labrax from the mediterranean were diagnosed with a severe encephalitis. rickettsia-like organisms (rlos) were associated with brain lesions in routine paraffin sections. these were found to share common antigens with the piscirickettsia salmonis type-strain, lf-89, by indirect fluorescent antibody test (ifat) and by immunohistochemistry (ihc). in addition, we compared the dna sequences of the 16s rdna and 16s-23s internal transcribed spacer region (its) with thos ... | 2005 | 15918473 |
| use of arthrobacter davidanieli as a live vaccine against renibacterium salmoninarum and piscirickettsia salmonis in salmonids. | arthrobacter davidanieli (proposed species nomenclature) is a non-pathogenic gram-variable bacterium related to, but taxonomically distinct from, renibacterium salmoninarum, the aetiological agent of bacterial kidney disease (bkd). we have demonstrated that vaccination with live a. davidanieli is effective against bkd in atlantic salmon (salmo salar) showing above 80 relative percent survival in experimental challenge trials. good protection was also demonstrated in long-term field trials where ... | 2005 | 15962482 |
| production and immune response of recombinant hsp60 and hsp70 from the salmon pathogen piscirickettsia salmonis. | we have isolated and sequenced the genes encoding the heat shock proteins 60 (hsp60) and 70 (hsp70) of the salmon pathogen piscirickettsia salmonis. the sequence analysis revealed the expected two open reading frames that encode proteins with calculated molecular weights of 60,060 and 70,400. the proteins exhibit a 70-80% homology with other known prokaryotic hsp60 and hsp70 sequences. the coding regions have been expressed in e. coli as thioredoxin fusion proteins. both recombinant proteins wer ... | 2005 | 15977412 |
| improved purification of piscirickettsia salmonis using percoll gradients. | viable preparations of intact piscirickettsia salmonis, purified from host cell material, are necessary for studying characteristics associated with this bacterium. however, purification of the organism is difficult due to its obligate intracellular nature. a simple and effective method for isolating whole p. salmonis, which is quick and easy to perform, but still maintains the viability and antigenicity of the bacterium is described. p. salmonis was purified by differential pelleting and densit ... | 2006 | 16434115 |
| occurrence of piscirickettsiosis-like syndrome in tilapia in the continental united states. | from 2001 to 2003, tilapia (oreochromis sp.) farms in florida, california, and south carolina experienced epizootics of a systemic disease causing mortality. the fish exhibited lethargy, occasional exophthalmia, and skin petechia. the gills were often necrotic, with a patchy white and red appearance. grossly, the spleen and kidneys were granular with whitish irregular nodules throughout. granulomatous infiltrates were observed in kidney, spleen, testes, and ovary tissues, but not in the liver. t ... | 2005 | 16475524 |
| a vaccine against the salmonid pathogen piscirickettsia salmonis based on recombinant proteins. | we report here the protective effect against piscirickettsiosis elicited in fish by a mixture of recombinant proteins. a comparative genomics strategy was used on a genomic library of piscirickettsia salmonis in order to select optimal candidates for a recombinant subunit vaccine to protect fish from rickettsial septicaemia (srs). based on this information, 15 p. salmonis orfs encoding heat shock proteins, virulence factors, membrane bound and other surface exposed antigens, were isolated and ex ... | 2006 | 16697089 |
| aquatic francisella-like bacterium associated with mortality of intensively cultured hybrid striped bass morone chrysops x m. saxatilis. | the present study identifies an emerging disease associated with an aquatic francisella-like bacterium that can cause mortality in hybrid striped bass morone chrysops x m. saxatilis reared intensively in freshwater. clinically affected fish were lethargic, had scattered haemorrhagic cutaneous lesions and diffuse gill pallor. the head kidney and spleen were markedly swollen and contained numerous interstitial granulomas; histological examination revealed small, pleomorphic gram-negative coccobaci ... | 2006 | 17140136 |
| immunological characterization of a bacterial protein isolated from salmonid fish naturally infected with piscirickettsia salmonis. | the salmon rickettsia syndrome (srs) remains a major infectious disease in the chilean aquaculture. a limited number of piscirickettsia salmonis proteins have been characterized so far for their use as potential candidates for vaccines studies. in this study, we identified and expressed a highly immunogenic protein of p. salmonis extracted by selective hydrophobicity from crude-cell macerates of naturally infected salmonid fish. one and two-d page gels followed by western blot analysis with a ba ... | 2007 | 17250933 |
| persistence of piscirickettsia salmonis and detection of serum antibodies to the bacterium in white seabass atractoscion nobilis following experimental exposure. | white seabass atractoscion nobilis surviving experimental exposure to piscirickettsia salmonis harbored the bacterium for periods up to at least 123 d post injection (dpi). intraperitoneal injections of juvenile white seabass with 1.26 x 10(2) tcid50 p. salmonis fish(-1) resulted in a 29% cumulative mortality over a 27 d period. both molecular and histologic methods provided evidence for persistence of the bacterium in fish sampled sequentially from the surviving population. throughout the perio ... | 2006 | 17260832 |
| agar culture of piscirickettsia salmonis, a serious pathogen of farmed salmonid and marine fish. | piscirickettsia salmonis, a serious bacterial pathogen of farmed marine fish, previously considered culturable only in eukaryotic cell-culture systems, was grown for the first time on agar and broth containing enhanced levels of cysteine, thus greatly increasing the potential for isolation, in vitro culture and study of this organism. virulence towards atlantic salmon following passage on agar media was retained in a controlled laboratory trial. of the studied temperatures, optimal growth on aga ... | 2008 | 18028392 |
| characterization of a novel and genetically different small infective variant of piscirickettsia salmonis. | we report a novel genetically different small infective variant of the fish pathogen piscirickettsia salmonis (sp.s). sp.s variants were recovered both from ageing post-infected chse-214 culture cells as well as from naturally infected fish. the its region of sp.s variants, although sharing a common core sequence, is different from the its of the prototype strain lf-89 from which they originate. thus, sp.s can be selectively amplified with sequence-specific discriminatory set of pcr primers. tra ... | 2008 | 18166333 |
| structural features of lipid a of piscirickettsia salmonis, the etiological agent of the salmonid rickettsial septicemia. | the composition and structure of lipid a isolated from the lipopolysaccharide (lps) of piscirickettsia salmonis were investigated by chemical analyses, gas chromatography/mass spectrometry (gcms), and electrospray ionization (esi) combined with the tandem mass spectrometry (ms/ms). our study revealed moderate compositional and structural heterogeneity of lipid a with respect to the content of phosphate groups and 4-amino-4-deoxy-l-arabinopyranose (ara4n) residues and with regard to the degree of ... | 2007 | 18197732 |
| culture of piscirickettsia salmonis on enriched blood agar. | piscirickettsia salmonis is the etiologic agent of piscirickettsiosis, an economically significant disease of fish. isolation of p. salmonis by culturing on fish cell lines has been the standard technique since the initial isolation of the organism. the ability to grow p. salmonis on artificial media would relieve facilities of the cost of maintaining cell lines, permit isolation at fish culture sites with fewer contamination problems, and allow easier transport of isolates to diagnostic facilit ... | 2008 | 18319435 |
| real time pcr detection of piscirickettsia salmonis from formalin-fixed paraffin-embedded tissues. | piscirickettsia salmonis is the causative agent of piscirickettsiosis, a transmissible disease of salmonid fish. diagnosis of piscirickettsiosis has traditionally been based upon identification of typical pathological changes by histological investigation, with confirmation by immunohistochemistry on formalin-fixed, paraffin-embedded tissues. however, implementation of more rapid confirmatory techniques, preferably with higher levels of sensitivity and possibilities for quantification, is desira ... | 2008 | 18681901 |
| survival and replication of piscirickettsia salmonis in rainbow trout head kidney macrophages. | piscirickettsia salmonis is pathogenic for a variety of cultured marine fish species worldwide. the organism has been observed within host macrophages in natural disease outbreaks among coho salmon and european sea bass. in vitro studies, incorporating transmission electron microscopy (tem) and ferritin loading of lysosomes, have confirmed that p. salmonis is capable of surviving and replicating in rainbow trout macrophages. certain features of this intracellular survival underline its differenc ... | 2008 | 18691656 |
| productive infection of piscirickettsia salmonis in macrophages and monocyte-like cells from rainbow trout, a possible survival strategy. | piscirickettsia salmonis is the etiologic agent of the salmonid rickettsial septicemia (srs), an endemic disease which causes significant losses in salmon production. this intracellular bacterium is normally cultured in salmonid epithelial cell lines inducing characteristic cytopathic effects (cpes). in this study we demonstrate that p. salmonis is able to infect, survive, replicate, and propagate in the macrophages/monocytes cell line rts11 derived from rainbow trout spleen, without inducing th ... | 2009 | 19681041 |
| determination of minimal concentration of piscirickettsia salmonis in water columns to establish a fallowing period in salmon farms. | abstract a highly sensitive real-time pcr procedure to detect and quantify the number of pisciricketsia salmonis units in seawater samples from affected farm sites has been developed. the purpose was to determine a fallowing period that would allow safe restocking of the target farm with new fish. bacterial load was determined in water samples by comparing the obtained amplification values against a standard curve generated by the amplification of known concentrations of the its-ribosomal compon ... | 2010 | 20088869 |
| an evaluation of potential reference genes for stability of expression in two salmonid cell lines after infection with either piscirickettsia salmonis or ipnv. | abstract: | 2010 | 20398263 |
| piscirickettsia salmonis induces apoptosis in macrophages and monocyte-like cells from rainbow trout. | piscirickettsia salmonis is the etiologic agent of the salmonid rickettsial septicemia (srs) which causes significant losses in salmon production in chile and other and in other regions in the southern hemisphere. as the killing of phagocytes is an important pathogenic mechanism for other bacteria to establish infections in vertebrates, we investigated whether p. salmonis kills trout macrophages by apoptosis. apoptosis in infected macrophages was demonstrated by techniques based on morphological ... | 2010 | 20432244 |
| lipopolysaccharide primes the respiratory burst of atlantic salmon shk-1 cells through protein kinase c-mediated phosphorylation of p47phox. | the superoxide-producing nadph oxidase complex of phagocytes plays a crucial role in host defenses against microbial infection. nadph oxidase consists of a membrane heterodimeric protein, composed of gp91phox and p22phox, and the cytosolic proteins, p40phox, p47phox and p67phox. in the present study, we clone and sequence the full-length cdnas coding for the atlantic salmon (salmo salar) phagocyte nadph oxidase components, p47phox, p67phox and gp91phox, using a homology cloning approach. the seq ... | 2010 | 20621116 |
| association of red-mark syndrome with a rickettsia-like organism and its connection with strawberry disease in the usa. | red-mark syndrome (rms), a disease seen mostly in rainbow trout, oncorhynchus mykiss, is of unknown aetiology. the research presented here indicates the presence of an intracellular bacterium in rms-affected fish. a positive reaction was observed using immunohistochemistry (ihc) with skin lesions, liver, kidney and spleen of affected fish sampled from several locations within the united kingdom using two different polyclonal antisera raised against piscirickettsia salmonis. the same reaction was ... | 2010 | 20854353 |
| glandular kallikrein in the innate immune system of atlantic salmon (salmo salar). | glandular kallikrein is a serine-protease with trypsin-like activity and is able to generate bioactive peptides from inactive precursors. we have evaluated the presence of this protease in the different organs of the atlantic salmon (salmo salar). the results clearly indicate that gk and prl are generated in the same pituitary cells based on a co-localization by confocal microscopy. based on probed cross-reactivity between c. striata and c. carpio glandular anti-gk antibodies, we used a homologo ... | 2010 | 20970199 |
| ispsa2, the first mobile genetic element to be described and characterized in the bacterial facultative intracellular pathogen piscirickettsia salmonis. | piscirickettsia salmonis is a novel, aggressive, facultative gram-negative bacterium that drastically affects salmon production at different latitudes, with particular impact in southern chile. initially, p. salmonis was described as a rickettsia-like, obligate, intracellular alphaproteobacteria, but it was reclassified recently as a facultative intracellular gammaproteobacteria. this designation has prompted the independent growth of the bacterium to a pure state for detailed study of its biolo ... | 2010 | 21073510 |
| piscirickettsia-like organisms as a cause of acute necrotic lesions in colombian tilapia larvae. | rickettsial organisms are well-known fish pathogens in both natural and culture environments. this study reports an outbreak of disease in red tilapia larvae caused by piscirickettsia-like organisms (plos), which lasted from june until october 2009. severe mortality was recorded almost exclusively in larvae and postlarvae aged 1-22 days old. although clinical or gross findings were not evident in diseased fish, histopathology revealed severe necrosis of the epidermis and gill epithelium, with co ... | 2011 | 21217048 |
| oral vaccination of atlantic salmon (salmo salar) against salmonid rickettsial septicaemia. | effective oral immunization systems may be very helpful to the salmon industry, particularly during the seawater growth stages in which vaccination through injection is not possible. during the seawater growing stage, fish become more susceptible to several types of disease, due to the natural decay of vaccine-induced immune responses. in this study, we demonstrate the immune response and efficacy of a new salmonid rickettsial septicaemia (srs) oral vaccine, developed using micromatrix™ technolo ... | 2011 | 21219985 |
| characterization of a functional toxin-antitoxin module in the genome of the fish pathogen piscirickettsia salmonis. | this is the first report of a functional toxin-antitoxin (ta) locus in piscirickettsia salmonis. the p. salmonis ta operon (ps-tox-antox) is an autonomous genetic unit containing two genes, a regulatory promoter site and an overlapping putative operator region. the orfs consist of a toxic ps-tox gene (p. salmonis toxin) and its upstream partner ps-antox (p. salmonis antitoxin). the regulatory promoter site contains two inverted repeat motifs between the -10 and -35 regions, which may represent a ... | 2011 | 21241361 |
| a natural peptide and its variants derived from the processing of infectious pancreatic necrosis virus (ipnv) displaying enhanced antimicrobial activity: a novel alternative for the control of bacterial diseases. | the larger segment of the infectious pancreatic necrosis virus (ipnv) codifies most of the structural and non-structural proteins of the virus in two overlapping open reading frames (orfs). the longer of the two orf is expressed as a polyprotein which generates a number of variable length peptides of unknown function during processing. since an appealing hypothesis would be that these peptides are generated by the virus to act as antimicrobial agents that favor viral infectivity in their fish ho ... | 2011 | 21291934 |
| Multiple tissue transcriptomic responses to Piscirickettsia salmonis in Atlantic salmon (Salmo salar). | The bacterium Piscirickettsia salmonis is the etiological agent of salmonid rickettsial septicemia (SRS), a severe disease that causes major economic losses to the Atlantic salmon aquaculture industry every year. Little is known about the infective strategy of P. salmonis, which is able to infect, survive within, and replicate inside salmonid macrophages as an intracellular parasite. Similarly there is little knowledge concerning the fish host's response to invasion by this pathogen. We have exa ... | 2011 | 21878610 |