Virulence and antigenic characteristics of a cultured Rickettsiales-like organism isolated from farmed Atlantic salmon Salmo salar in eastern Canada

Jones, Simon R. M.; Markham, Robert; Groman, David B.; Cusack, R.

doi:10.3354/dao033025

Cited by 33 publications

(25 citation statements)

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“…About half of these were reported in the United States (G. S. Visvesvara, personal communication). Although CNS infections due to Acanthamoeba and Balamuthia have been recorded in animals, such as dogs, sheep, cattle, primates, and horses, 1,4,[9][10][11]15,16 there has been only 1 report of naturally acquired PAM in animals, namely in a South American tapir at a zoo in Arizona. 6 Primary amoebic meningoencephalitis has been experimentally induced in mice, sheep, and monkeys.…”

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confidence: 99%

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Occurrence of Piscirickettsiosis-Like Syndrome in Tilapia in the Continental United States

et al. 2005

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Abstract. From 2001to 2003 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. The granulomas contained pleomorphic coccoid bacteria, measuring 0.57 Ϯ 0.1 ϫ 0.8 Ϯ 0.2 m, that were Giemsa-positive, acid-fast-negative, and Gram-negative. The bacteria had a double cell wall, variable electron-dense and -lucent areas, and were present in the cytoplasm and within phagolysosomes. The syndrome was associated with cold stress and poor water conditions. These findings are consistent with an infectious process caused by a Piscirickettsia-like bacterium described previously in tilapia in Taiwan and Hawaii. This report involves the first identified cases of a piscirickettsiosis-like syndrome affecting tilapia in the continental United States.Key words: Piscirickettsiosis; Piscirickettsia-like organisms; piscirickettsiosis-like syndrome; Tilapia.Since the identification of Piscirickettsia salmonis as the first rickettsia-like organism recognized as a fish pathogen, 9 a number of Piscirickettsia-like organisms (PLOs) have been observed microscopically or isolated in cell culture from a variety of marine and fresh-water piscine species from locations worldwide. 5,11,12,16 Piscirickettsiosis or piscirickettsiosis-like syndromes can be severe, resulting in high mortality and significant economic losses.The number of reports of piscirickettsiosis, with significant associated economic losses, have been increasing for the last 5-10 years in British Columbia, 2,8 Ireland, 16 and Scotland. 10 PLOs have also been observed in and isolated from seabass in Europe 1,7 and California 3 during epizootics characterized by high mortality and severe economic losses. Tilapia in Taiwan 4,6 and Hawaii 15 have also been severely affected by PLO epizootics. Here we report on the first identified cases of PLO epizootics in tilapia in the continental United States.Between 2001 and 2003, 3 facilities in the continental United States (California, South Carolina, and Florida) reported epizootics with signs consistent with a piscirickettsiosis-like syndrome. All 3 facilities had increased mortalities during times of fish stress due to lowered temperature or water quality. The fish appeared lethargic, with darkened color, and would crowd toward the middle of the pond or tank. Occasionally, petechia were observed on the sides of the fish. Fins had light fraying, some exophthalmia was observed, and gills were necrotic, with a patchy white and red appearance. Internally, the spleen and kidneys were extremely granular with whitish irregular nodules throughout. The liver was a pale reddish tan with patchy lighter areas.In hematoxylin and eosin (HE) sections, the spl...

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“…5,11,12,16 Piscirickettsiosis or piscirickettsiosis-like syndromes can be severe, resulting in high mortality and significant economic losses.…”

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Occurrence of Piscirickettsiosis-Like Syndrome in Tilapia in the Continental United States

et al. 2005

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“…Piscirickettsiosis or salmonid rickettsia1 septicemia soon became evident in other salmonids (Atlantic salmon Salmo salar and rainbow trout Oncorhynchus mykiss) in both the northern and southern hemispheres (Fryer & Lannan 1996, Almendras & Fuentealba 1997, Olsen et al 1997, Jones et al 1998. The microbial etiology of these outbreaks has been confirmed by determination of close phylogenetic affiliations to Piscirickettsia salmonis LF-89 (Mauel et al 1996(Mauel et al , 1999, serological criteria (Olsen et al 1997) and comparative biochemistry of the microbial antigens (Jones et al 1998).…”

Section: Introductionmentioning

confidence: 92%

“…The microbial etiology of these outbreaks has been confirmed by determination of close phylogenetic affiliations to Piscirickettsia salmonis LF-89 (Mauel et al 1996(Mauel et al , 1999, serological criteria (Olsen et al 1997) and comparative biochemistry of the microbial antigens (Jones et al 1998). However, severe epizootics of P. salmonis occur only in the fish farms of southern Chile, while outbreaks of the organism in other parts of the world have been less pronounced and sporadic (for reviews, see Fryer & Lannan 1996, House et al 1999.…”

Section: Introductionmentioning

confidence: 99%

Monitoring Piscirickettsia salmonis by denaturant gel electrophoresis and competitive PDAO

Heath¹,

Pak²,

Marshall³

et al. 2000

Dis. Aquat. Org.

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Reported strains of Piscirickettsia salmonis, a pathogen of salmonid fishes, were analyzed by amplifying part of the internal transcribed spacer (ITS) of the nbosomal RNA (rRNA) operon followed by denaturing gradient gel electrophoresis (DGGE) of the amphcons. AU 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 1998 of salmonids from 5 different sites on and near Chilok Island in southern Chile displaying piscirickettsiosis revealed only P. salmonis resembling LF-89, the type strain first isolated in 1989. These observations are encouraging for control strategies, which might otherwise be compromised by unpredictable shifts of P. salmonis types in salmon farms A competitive PCR assay offered insight about the power of PCR for quantification and about specific tissue invasiveness by this intracellular pathogen. This approach revealed that the PCR could amplify approximately 1 to 10 P. salmonis genome equivalents against a background of >99.9% salmonid DNA. It also raised the possibility that the salmonid brain is an important site for P. salmonjs survival, with its bacterial load in 1 individual having been about 100 times the loads observed in liver and kidney. Pathogen detection by competitive PCR in a surface seawater sample from a netpen in use indicated a density of about 3000 to 4000 P salmonis cells (or their DNA remnants) 1-' Such quantitative estimates should aid decisions about disease prevention and management as, for example, choice of netpen sites following fallow periods and certification of ova, which are known conduits of infection.

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“…Nevertheless, as a simple first step in evaluating any potential variation in virulence, parallel TRLO challenges could be performed using standardised doses and environmental conditions. Serotypic diversity amongst TRLO isolates is novel in that to date there is no evidence of such variation within the P. salmonis species despite its antigenic characterisation (Kuzyk et al 1996, Barnes et al 1998, Jones et al 1998. There is evidence of differences in virulence be tween P. salmonis isolates (House et al 1999), but antigenic variability has yet to be identified.…”

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Isolation of Tasmanian Rickettsia-like organism (RLO) from farmed salmonids: identification of multiple serotypes and confirmation of pathogenicity

Morrison¹,

Young²,

Knowles³

et al. 2016

Dis. Aquat. Org.

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Atlantic salmon Salmo salar L. farmed in south-east Tasmania, Australia, are susceptible to infection by the Tasmanian Rickettsia-like organism (TRLO), a Gram-negative bacterium. Here, we report the first isolation of TRLO from south-east Tasmania in pure culture and show that the bacterium is culturable on both specialised enriched agar and in cell culture using the CHSE-214 cell line. In vitro cultured TRLO was used to reproducibly elicit disease in Atlantic salmon parr held in fresh water. In inoculated fish, TRLO was observed intracytoplasmically in peripheral blood leucocytes, suggesting that these cells are responsible for haematogenous dispersal of the bacterium within the host. Fish with experimentally induced disease presented with gross and histopathological changes similar to TRLO-infected fish at commercial marine farms. TRLO was also isolated in culture from farmed Atlantic salmon in the Tamar River and Macquarie Harbour production areas in Tasmania, both of which have no history of TRLO-associated disease. These TRLO isolates appear to be serologically distinct from each other as well as from isolates obtained from south-east Tasmania, linking each serotype to a specific geographical location within Tasmania. Despite the lack of clinical evidence of TRLO-linked disease in fish grown in the Tamar River and Macquarie Harbour, experimental infection trials demonstrably showed the pathogenic potential of these TRLO serovars. Together, these data provide evidence that TRLO is a fastidious, facultative intracellular bacterium and confirm TRLO as a pathogen of Atlantic salmon, causing a disease designated Tasmanian salmonid rickettsiosis.KEY WORDS: Rickettsia-like organism · TRLO · Atlantic salmon · Salmo salar · Culture · Pathogenicity · Tasmania Resale or republication not permitted without written consent of the publisherDis Aquat Org 122: [85][86][87][88][89][90][91][92][93][94][95][96][97][98][99][100][101][102][103] 2016 RLO (Khoo et al. 1995, Athanassopoulou et al. 2004, Corbeil et al. 2005, Wu et al. 2005 or P. salmonis-like organism (Antonio et al. 2000, Chen et al. 2000a,b, Mauel et al. 2003 until their taxonomic status can be formally resolved. This includes the Tasmanian RLO (TRLO), a bacte rium detected in Atlantic salmon Salmo salar L. farmed on the south-east coast of Tasmania, Austra lia (Corbeil et al. 2005).TRLO is an intracellular, Gram-negative coccoid bacterium that emerged in the summer of 2001 (Department of Primary Industries, Parks, Water and Environment [DPIPWE] unpublished data). Since then, TRLO has been implicated in minor sporadic outbreaks of disease which have typically coincided with the annual peak in water temperature. The disease is characterised by a high morbidity rate which results in significant production loss through reduced feed intake but relatively low mortality, less than 10% of affected stock. During outbreaks, affected fish are commonly co-infected with the Tasmanian Atlantic salmon reovirus (TSRV; Zainathan et al. 2015), and it is not known wh...

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Virulence and antigenic characteristics of a cultured Rickettsiales-like organism isolated from farmed Atlantic salmon Salmo salar in eastern Canada

Cited by 33 publications

References 10 publications

Occurrence of Piscirickettsiosis-Like Syndrome in Tilapia in the Continental United States

Occurrence of Piscirickettsiosis-Like Syndrome in Tilapia in the Continental United States

Monitoring Piscirickettsia salmonis by denaturant gel electrophoresis and competitive PDAO

Isolation of Tasmanian Rickettsia-like organism (RLO) from farmed salmonids: identification of multiple serotypes and confirmation of pathogenicity

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