Fig 2 - uploaded by Alberto J. Villena
Content may be subject to copyright.
![Ultrastructure of the thymus in Renibacterium salmoninarum-infected coho salmon Oncorhynchus kisutch at 6 w.p.i. (A) Micrograph showing the disorganization of the thymic capsule close to the basal membrane (arrows). 1: limiting reticularepithelial cell; f: fibroblast; star: connective fibres; arrowheads: bacteria. (B) Micrograph showing the capsule (C) and subcapsular zone (SZ). Note the discontinuities of the capsular-thymic barrier (thick arrows), in which bacteria appear. 1: limiting reticular-epithelia1 cells in a necrotic state; f: fibroblast; star: connective fibres; arrowheads: bacteria. (C) Low power view of the inner (12) and outer (OZ) zones, and of the pharyngeal epithelium (E). Note the presence of bacteria in the gill chamber (GC). e: pharyngeal epithelia1 cell; m: mucous cell; o: reticular-epithelia] cells of the outer zone; p: pale reticular-epithelia1 cell; t: thymocyte; arrowhead. bacteria. Scale bars = 1 pm](profile/Alberto-Villena/publication/238451383/figure/fig2/AS:671518736543753@1537113951771/Ultrastructure-of-the-thymus-in-Renibacterium-salmoninarum-infected-coho-salmon.jpg)
Ultrastructure of the thymus in Renibacterium salmoninarum-infected coho salmon Oncorhynchus kisutch at 6 w.p.i. (A) Micrograph showing the disorganization of the thymic capsule close to the basal membrane (arrows). 1: limiting reticularepithelial cell; f: fibroblast; star: connective fibres; arrowheads: bacteria. (B) Micrograph showing the capsule (C) and subcapsular zone (SZ). Note the discontinuities of the capsular-thymic barrier (thick arrows), in which bacteria appear. 1: limiting reticular-epithelia1 cells in a necrotic state; f: fibroblast; star: connective fibres; arrowheads: bacteria. (C) Low power view of the inner (12) and outer (OZ) zones, and of the pharyngeal epithelium (E). Note the presence of bacteria in the gill chamber (GC). e: pharyngeal epithelia1 cell; m: mucous cell; o: reticular-epithelia] cells of the outer zone; p: pale reticular-epithelia1 cell; t: thymocyte; arrowhead. bacteria. Scale bars = 1 pm
Source publication
We report on the histopathological changes occurring in the thymus of coho salmon Oncorhynchus kisutch experimentally infected with Renibacterium salmoninarum. Coho salmon were intraperitoneally infected, and the thymi were collected weekly from 1 to 7 wk post-infection, and processed for ultrastructural study. The thymus appeared to be infected on...
Contexts in source publication
Context 1
... a n increase in the number of bacteria in the capsule, and presence of bacteria in the subcapsular and inner zones of the parenchyma (Fig. 1C). In the capsule, masses of bacteria occurred in association with the basal membrane, which forms part of the capsular- thymic barlier (Fig. 1C). Most bacteria in the capsule were located extracellularly ( Fig. 2A), but fibroblasts also appeared to be invaded by Renibacterium sal- moninarum ( Fig. 2A). The necrosis of the connective tissue was accompanied by the disruption of the col- lagen fibres and of the basal membrane ( Fig. 2A), and necrosis of the limiting reticular-epithelia1 cells (Fig. ...
Context 2
... subcapsular and inner zones of the parenchyma (Fig. 1C). In the capsule, masses of bacteria occurred in association with the basal membrane, which forms part of the capsular- thymic barlier (Fig. 1C). Most bacteria in the capsule were located extracellularly ( Fig. 2A), but fibroblasts also appeared to be invaded by Renibacterium sal- moninarum ( Fig. 2A). The necrosis of the connective tissue was accompanied by the disruption of the col- lagen fibres and of the basal membrane ( Fig. 2A), and necrosis of the limiting reticular-epithelia1 cells (Fig. ...
Context 3
... which forms part of the capsular- thymic barlier (Fig. 1C). Most bacteria in the capsule were located extracellularly ( Fig. 2A), but fibroblasts also appeared to be invaded by Renibacterium sal- moninarum ( Fig. 2A). The necrosis of the connective tissue was accompanied by the disruption of the col- lagen fibres and of the basal membrane ( Fig. 2A), and necrosis of the limiting reticular-epithelia1 cells (Fig. ...
Context 4
... Most bacteria in the capsule were located extracellularly ( Fig. 2A), but fibroblasts also appeared to be invaded by Renibacterium sal- moninarum ( Fig. 2A). The necrosis of the connective tissue was accompanied by the disruption of the col- lagen fibres and of the basal membrane ( Fig. 2A), and necrosis of the limiting reticular-epithelia1 cells (Fig. ...
Context 5
... the parenchyma, bacteria were located mainly in the cytoplasm of macrophages (Figs. l C , 2C & 3A), some of which appeared lysed (Figs. 2C & 3A). Often, the macrophages contained large cell debris, possibly of host-cell origin (Fig. 3A). The bacteria also appeared frequently colonizing the cytoplasm of pale reticular- epithelial cells (Fig. 3B), while most peritrabecular, dark reticular-epithelia1 cells (Fig. 3C) and those of the ...
Context 6
... the parenchyma, bacteria were located mainly in the cytoplasm of macrophages (Figs. l C , 2C & 3A), some of which appeared lysed (Figs. 2C & 3A). Often, the macrophages contained large cell debris, possibly of host-cell origin (Fig. 3A). The bacteria also appeared frequently colonizing the cytoplasm of pale reticular- epithelial cells (Fig. 3B), while most peritrabecular, dark reticular-epithelia1 cells (Fig. 3C) and those of the outer zone (Fig. 2C) were free of Renibactenum ...
Context 7
... some of which appeared lysed (Figs. 2C & 3A). Often, the macrophages contained large cell debris, possibly of host-cell origin (Fig. 3A). The bacteria also appeared frequently colonizing the cytoplasm of pale reticular- epithelial cells (Fig. 3B), while most peritrabecular, dark reticular-epithelia1 cells (Fig. 3C) and those of the outer zone (Fig. 2C) were free of Renibactenum sal- moninarum. Most trabeculae were also free of bacteria (Fig. 3C). Some thymocytes, mainly those located near other heavily infected cell types, contained a large number of bacteria and appeared lysed (Figs. 2C & 3B, C). The integrity of the pharyngeal epithelium covering the thymus was not affected during ...
Context 8
... thymocytes, mainly those located near other heavily infected cell types, contained a large number of bacteria and appeared lysed (Figs. 2C & 3B, C). The integrity of the pharyngeal epithelium covering the thymus was not affected during the in- fection, and although bacteria were present in the branchial cavity, they did not invade the epithelium (Fig. ...
Similar publications
Selective fishing is the ability of a fishing operation to avoid non-target species or stocks, or when encountered, to capture and release them in a manner that minimizes mortality. The tangle net was tested on the Willapa River to selectively harvest adult chinook salmon (Oncorhynchus tschawytscha) and coho salmon (O. kisutch). Experienced gill ne...
Combined effects of predation by benthic and drift-foraging fish (prickly sculpin ( Cottus asper) and coho salmon (Onchorhynchus kisutch) parr) on benthic invertebrate community and trophic structure were evaluated in May- fly Creek, a previously fishless stream in the Coast Range Mountains of British Columbia. The role of microhabitat (substrate)...
The Upper Columbia United Tribes (UCUT; Spokane, Colville, Kootenai, Coeur d’Alene, and Kalispel Tribes) and Washington Department of Fish and Wildlife want to reintroduce anadromous salmonids to their historical range to restore ecosystem function and lost cultural and spiritual relationships in the upper Columbia River, northeastern Washington. T...
Citations
... In the zipper mechanism, the interaction of bacterial surface proteins with host proteins causes cytoskeleton and membrane rearrangements, resulting in the pathogen's internalization [81]. Because R. salmoninarum has an affinity for phagocytes, sinusoidal cells, and reticular and barrier cells, a putative mechanism (i.e., zipper) (A in Figure 4) of its intracellular invasion has been linked to the surface protein p57 [94]. This mechanism involves C3b, a complement pathway opsonin, binding to the bacterial surface, ligation to C3b-receptor-bearing salmonid phagocytes, and subsequently increased internalization [95] ( Figure 4). ...
Complex interactions between marine Gram-positive pathogens and fish hosts in the marine environment can result in diseases of economically important finfish, which cause economic losses in the aquaculture industry. Understanding how these pathogens interact with the fish host and generate disease will contribute to efficient prophylactic measures and treatments. To our knowledge, there are no systematic reviews on marine Gram-positive pathogens. Therefore, here we reviewed the host–pathogen interactions of marine Gram-positive pathogens from the pathogen-centric and host-centric points of view.
... In concordance with BKD histopathology, congested glomeruli were observed in the head kidney of infected lumpfish at 14 and 42 dpi (Figures 3L, N). Also, lysed and disrupted melanomacrophages resulting from the dispersal of pigments in tissues during BKD (79,80) were observed in spleen and liver from infected lumpfish at 42 dpi ( Figures 3D, I). ...
Renibacterium salmoninarum is a Gram-positive, intracellular pathogen that causes Bacterial Kidney Disease (BKD) in several fish species in freshwater and seawater. Lumpfish (Cyclopterus lumpus) is utilized as a cleaner fish to biocontrol sea lice infestation in Atlantic salmon (Salmo salar) farms. Atlantic salmon is susceptible to R. salmoninarum, and it can transfer the infection to other fish species. Although BKD outbreaks have not been reported in lumpfish, its susceptibility and immune response to R. salmoninarum is unknown. In this study, we evaluated the susceptibility and immune response of lumpfish to R. salmoninarum infection. Groups of lumpfish were intraperitoneally (i.p.) injected with either R. salmoninarum (1×10⁷, 1×10⁸, or 1×10⁹ cells dose⁻¹) or PBS (control). R. salmoninarum infection kinetics and mortality were followed for 98 days post-infection (dpi). Transcript expression levels of 33 immune-relevant genes were measured in head kidney (n = 6) of fish infected with 1×10⁹ cells/dose and compared to the control at 28 and 98 dpi. Infected lumpfish displayed characteristic clinical signs of BKD. Lumpfish infected with high, medium, and low doses had a survival rate of 65%, 93%, and 95%, respectively. Mortality in the high-dose infected group stabilized after 50 dpi, but R. salmoninarum persisted in the fish tissues until 98 dpi. Cytokines (il1β, il8a, il8b), pattern recognition receptors (tlr5a), interferon-induced effectors (rsad2, mxa, mxb, mxc), and iron regulation (hamp) and acute phase reactant (saa5) related genes were up-regulated at 28 dpi. In contrast, cell-mediated adaptive immunity-related genes (cd4a, cd4b, ly6g6f, cd8a, cd74) were down-regulated at 28 dpi, revealing the immune suppressive nature of R. salmoninarum. However, significant upregulation of cd74 at 98 dpi suggests induction of cell-mediated immune response. This study showed that R. salmoninarum infected lumpfish in a similar fashion to salmonid fish species and caused a chronic infection, enhancing cell-mediated adaptive immune response.
... The granulomas in Pacific salmon are characteristically diffuse with poorly defined borders, whereas those in Atlantic salmon are more encapsulated and contain numerous epithelioid macrophages (Evelyn, 1993). Evidence indicates that the bacterium can survive and perhaps multiply within macrophages (Young and Chapman, 1978;Bruno, 1986;Bandín et al., 1993;Flaño et al., 1996;Dale et al., 1997). ...
Bacterial kidney disease (BKD) of salmonid fishes, caused by Renibacterium salmoninarum , has been recognized as a serious disease in salmonid fishes since the 1930s. This chapter discusses the occurrence and significance, etiology, and pathogenesis of vibriosis. It then describes the different vaccination procedures and the effects and side-effects of vaccination. Despite years of research, however, only a single vaccine has been licensed for prevention of BKD, and has demonstrated variable efficacy. Therefore, in addition to a presentation of the current status of BKD vaccination, a discussion of potential future directions for BKD vaccine development is included in the chapter. This discussion is focused on the unique characteristics of R. salmoninarum and its biology, as well as aspects of the salmonid immune system that might be explored specifically to develop more effective vaccines for BKD prevention.
... The reason for the different pathological presentation between species is unknown. Thymic infection can occur in experimentally infected coho salmon (Flano et al., 1996a). ...
... It is well documented that R. salmoninarum can be transmitted vertically from parents to offspring (Evelyn et al., 1984(Evelyn et al., , 1986a. Horizontal transmission is believed to occur primarily through the oral-fecal route (Balfry et al., 1996) and, to some extent, through the gills (Flañ o et al., 1996;MacIntosh et al., 2000) and skin lesions (Evenden et al., 1993). Once the infection is established, R. salmoninarum secretes a number of soluble proteins that play a role in pathogenicity (Bruno, 1986;Wiens and Kaattari, 1991;Hamel, 2001). ...
... Kidneys are the primary targets of R. salmoninarum (Fryer and Sanders, 1981); however, other organs should also be assessed in future studies to better under-stand BKD pathogenesis, particularly in natural infections. So far, the relatively few studies addressing BKD course and progression of infection have relied upon experimental infection (White et al., 1995;Flañ o et al., 1996). Moreover, further correlation of diagnostic testing patterns with clinical observations and tissue alterations in stained sections are needed to better evaluate impacts of R. salmoninarum infection at the population level. ...
Bacterial kidney disease (BKD), caused by Renibacterium salmoninarum, is a slowly progressing disease that threatens salmon conservation and restoration programs in North America. The purpose of this study was to track naturally occurring R. salmoninarum infection in representative, Michigan, USA, salmonid stocks using nested polymerase chain reaction (nPCR), quantitative enzyme-linked immunosorbent assay (Q-ELISA), and culture. The Q-ELISA test detected 67.6% infection prevalence, which is lower than culture (77.2%) or nPCR (94.2%), yet it provided semiquantitative data on infection intensity. The disagreement in results among the three assays may reflect the different phases of R. salmoninarum infection at the time of sampling. The testing results demonstrated the presence of six patterns, with each of the patterns representing a probable stage along the course of natural R. salmoninarum infection. Findings also suggest that fish stocks tested in this study were not uniform in the distribution of the diagnostic patterns and that, from studying such patterns, one can determine the course of BKD infection in a particular population.
... Renibacterium salmoninarum can induce uptake by non-phagocytic cells and can survive ingestion, which provides a means of entry into the host via the gills and the gastrointestinal tract (Evelyn 1996;Flaño et al. 1996;Balfry et al. 1996), however a study demonstrated that R. salmoninarum can not be internalized by healthy rainbow trout gills in vitro (McIntosh et al. 2000). ...
... Kidneys are the primary targets of R. salmoninarum (Fryer and Sanders, 1981); however, other organs should also be assessed in future studies to better understand BKD pathogenesis, particularly in natural infections. So far, the relatively few studies addressing BKD course and progression of infection relied upon experimental infection (Flaño et al 1996, White et al. 1995 The BKD testing of both feral spawners and their hatchery raised offspring fingerlings demonstrates that the current testing and culling programs have been successful in reducing R. salmoninarum transmission. This study also demonstrates that some hatchery practices were more effective than others in controlling the spread of R. salmoninarum and that a reliable improvement in the reduction of R. salmoninarum prevalence within the hatcheries involved in this study has been achieved. ...
Thesis (Ph. D.)--Michigan State University. Dept. of Pathobiology and Diagnostic Investigaion, 2005. Includes bibliographical references (leaves 189-210). Microfiche. s
This datasheet on bacterial kidney disease covers Identity, Overview, Associated Diseases, Pests or Pathogens, Distribution, Hosts/Species Affected, Diagnosis, Pathology, Epidemiology, Impacts, Prevention/Control, Further Information.
This review is devoted to a comparative histological analysis of non-lymphoid thymic cell populations in fish and mammals. The structures and functions of these cells, as well as their role in the formation of the blood-thymus barrier, are discussed. Data that point to the involvement of the thymus in the immune response of fish are given.
Renibacterium sp. QD1, a bacteria strain capable of hydrolysing chitosan, was isolated from the homogenate of small crabs. An extracellular chitosanase, Csn-A, was purified from the QD1 fermentation broth. The enzyme was purified to homogeneity, with a yield of eight-fold, 67% recovery and a specific activity of 1575 U/mg proteins. The molecular weight of Csn-A was estimated to be 26.1 kDa by SDS-PAGE. Unlike other chitosanases, the purified Csn-A displayed maximal activity at a pH range of 5.3–6.5, and it was stable in a broad pH range of 5.0–10.0. The optimum temperature for chitosanlytic activity was 55°C. The enzyme activity was strongly stimulated by Mn2+
but inhibited by Fe3+, Cu2+, Al3+, Zn2+ and SDS. TLC analysis demonstrated that Csn-A hydrolysed N-deacetylated polymeric glucosamines into chito-biose and -triose in an endo-type manner. The amino acid seuquence of Csn-A showed close identity with an uncharacterized chitosanase of strain ATCC33209.
This chapter discusses the occurrence of infections and diseases in fishes. In larval fish, infections through the gastrointestinal tract are quite likely to occur with a wide range of fish pathogens because the lethal secretions in the stomach, present in fish at a later stage of development, may still largely be absent. Infections with the kidney disease bacterium, Renibacterium salmoninarum, have been successfully established by the feeding of infected material, and in Pacific salmon farmed in sea water, infections by this route probably help to account for the increasing prevalence of bacterial kidney disease during their rearing. Evidence for the invasion of fish through the intact skin has been convincingly demonstrated with only one bacterial fish pathogen, V. anguillamm. By using routine histopathological techniques, it was been found that in natural and experimental infections of ayu, the skin was the first tissue to be colonized. In Aeromonas salmonicida, serum resistance appears to be related to a protein layer (the A layer) that envelopes the cell and to the long side chains of the A. salmonicida lipopolysaccharide (LPS) that traverse the A layer.
