RESUMEN
Myxobolus lentisuturalis is a myxozoan parasite of piscine muscle that has been described in goldfish Carassius auratus and Prussian carp Carassius gibelio. This report documents a naturally occurring infection of M. lentisuturalis in a population of farmed goldfish in the USA. Postmortem examination was performed on 4 affected goldfish. Gross findings included large cystic cavities along the dorsal midline filled with caseous exudate. Histopathology revealed myxozoan plasmodia and spores in the epaxial muscles with varying degrees of granulomatous and necrotizing myositis accompanied by lymphohistiocytic meningoencephalitis. Spore morphology and dimensions were consistent with M. lentisuturalis, as observed by light microscopy. PCR and sequence analysis of the small subunit ribosomal DNA of infected muscle samples from 2 goldfish confirmed the parasite to have 99-100% nucleotide identity to M. lentisuturalis sequences recovered from similar cases of this parasite infecting goldfish in China and Italy and Prussian carp in China. This is the first reported case of M. lentisuturalis in the USA and furthers the understanding of the pathogenicity of this under-described parasite.
Asunto(s)
Enfermedades de los Peces , Myxobolus , Enfermedades Parasitarias en Animales , Animales , Enfermedades de los Peces/parasitología , Carpa Dorada/parasitología , Myxobolus/genética , Enfermedades Parasitarias en Animales/epidemiología , Enfermedades Parasitarias en Animales/parasitología , FilogeniaRESUMEN
Anadromous river herring have declined in many parts of their range, leading to fisheries management efforts to help repopulate this species by improving connectivity of rivers and restoring populations by fish transfers. With data lacking on parasites in these species, this study sought to better understand myxozoans across various life stages and habitats in river herring populations in New Jersey, USA. We compared fish from riverine habitats during early-life growth and adults returning to spawn, marine-phase fish, and landlocked Alewife populations. Three myxozoan species were identified in young-of-the-year (YOY) anadromous river herring, including Kudoa clupeidae in the skeletal musculature, Myxobolus mauriensis in the rib cartilage, and an uncharacterized coelozoic myxozoan within the lumen of mesonephric tubules. In YOY river herring, Blueback Herring were 2 times more likely to be infected by K. clupeidae than Alewife (p = 0.019) and in the Maurice River, fish were 4 times more likely to be infected with M. mauriensis than fish from Great Egg Harbor River (p = 0.000) and 11 times more likely than the Delaware River (p = 0.001). Spawning adult river herring were infected with a previously undescribed myxozoan parasite infecting the kidney. Sequencing the 18S rDNA indicated this species is closely related to Ortholinea species. Myxobolus mauriensis and the Ortholinea-like species were absent from marine-phase river herring indicating that infections were linked to river environments occurring during early-life growth and spawning, respectively. No myxozoans were present in landlocked Alewife, showing that similar infections occurring in rivers were absent in lake environments in the region.
Asunto(s)
Enfermedades de los Peces , Parásitos , Animales , Ecosistema , Enfermedades de los Peces/epidemiología , Peces , Estadios del Ciclo de Vida , RíosRESUMEN
Wild bluegill, Lepomis macrochirus Rafinesque, succumb to seasonal mortality in the early spring during cool water temperatures, shown previously to be related to bacteraemia caused by a psychrotrophic bacterium, Pseudomonas mandelii. In the study herein, intestinal coccidiosis in wild bluegill had seasonal prevalence causing heavy intestinal infections and sloughing of intestinal epithelium occurring in late winter/early spring. Infections were predominantly related to two different species, Goussia washuti n. sp., an epicellular coccidium, and a coccidium closely resembling Goussia desseri Molnár 1996, previously only described in percid fish in Europe. In 2019, co-infections of bacteraemia and intestinal coccidiosis occurred in bluegills. Evaluating coccidium infection intensity by fresh parasite examination and histology, an association was observed in which fish with moderate-to-heavy intestinal coccidiosis were 8-12 times more likely to have bacteraemia compared to fish with no or light coccidiosis. The association of these co-infections suggests that intestinal coccidiosis could contribute to seasonal bacterial epizootics of wild bluegill.
Asunto(s)
Coccidiosis/diagnóstico , Enfermedades de los Peces/microbiología , Enfermedades de los Peces/parasitología , Parasitosis Intestinales/veterinaria , Perciformes/parasitología , Infecciones por Pseudomonas/veterinaria , Estaciones del Año , Animales , Bacteriemia/mortalidad , Bacteriemia/veterinaria , Coccidiosis/microbiología , Coccidiosis/patología , Frío , Enfermedades de los Peces/mortalidad , Parasitosis Intestinales/diagnóstico , Parasitosis Intestinales/microbiología , Perciformes/microbiología , Pseudomonas/patogenicidad , Infecciones por Pseudomonas/mortalidad , Infecciones por Pseudomonas/parasitologíaRESUMEN
Enteromyxum leei is an enteric myxozoan parasite of fish. This myxozoan has low host specificity and is the causative agent of myxozoan emaciation disease, known for heavy mortalities and significant financial losses within Mediterranean, Red Sea, and Asian aquaculture industries. The disease has rarely been documented within public aquaria and, to our knowledge, has never been confirmed within the USA. This case report describes an outbreak of E. leei in a population of mixed-species east African/Indo-Pacific marine fish undergoing quarantine at a public aquarium within the USA. Four of 16 different species of fish in the population, each of a different taxonomic family, were confirmed infected by the myxozoan through cloacal flush or intestinal wet mount cytology at necropsy. Clinical and histopathological findings in this case are similar to previous findings describing myxozoan emaciation disease, e.g. severe emaciation, cachexia, enteritis, and death. Sequence analysis of the 18S rDNA of intestinal samples from a powder blue tang Acanthurus leucosternon and an emperor angelfish Pomacanthus imperator confirmed the parasite to have 99-100% identity with other E. leei sequences. Spore morphology and ultrastructure were consistent with previous reports of E. leei. Treatment of clinically affected fish by oral administration of the coccidiostats amprolium and salinomycin led to reduction of mortalities and resolution of clinical signs. This case report highlights the importance of thorough examination and surveillance of fish during quarantine, particularly with respect to enteric myxozoans.
Asunto(s)
Enfermedades de los Peces , Myxozoa , Animales , Peces , Océano Índico , CuarentenaRESUMEN
Surveillance for pathogens of Atlantic herring, including viral hemorrhagic septicemia virus (VHSV), Ichthyophonus hoferi, and hepatic and intestinal coccidians, was conducted from 2012 to 2016 in the NW Atlantic Ocean, New Jersey, USA. Neither VHSV nor I. hoferi was detected in any sample. Goussia clupearum was found in the livers of 40 to 78% of adult herring in varying parasite loads; however, associated pathological changes were negligible. Phylogenetic analysis based on small subunit 18S rRNA gene sequences placed G. clupearum most closely with other extraintestinal liver coccidia from the genus Calyptospora, though the G. clupearum isolates had a unique nucleotide insertion between 604 and 729 bp that did not occur in any other coccidian species. G. clupearum oocysts from Atlantic and Pacific herring were morphologically similar, though differences occurred in oocyst dimensions. Comparison of G. clupearum genetic sequences from Atlantic and Pacific herring revealed 4 nucleotide substitutions and 2 gaps in a 1749 bp region, indicating some divergence in the geographically separate populations. Pacific G. clupearum oocysts were not directly infective, suggesting that a heteroxenous life cycle is likely. Intestinal coccidiosis was described for the first time from juvenile and adult Atlantic herring. A novel intestinal coccidian species was detected based on morphological characteristics of exogenously sporulated oocysts. A unique feature in these oocysts was the presence of 3 long (15.1 ± 5.1 µm, mean ±SD) spiny projections on both ends of the oocyst. The novel morphology of this coccidian led us to tentatively name this parasite G. echinata n. sp.
Asunto(s)
Coccidios/clasificación , Coccidiosis/veterinaria , Enfermedades de los Peces/parasitología , Peces , Intestinos/parasitología , Parasitosis Hepáticas/veterinaria , Animales , Océano Atlántico/epidemiología , Secuencia de Bases , Coccidios/genética , Coccidios/aislamiento & purificación , Coccidiosis/epidemiología , Coccidiosis/parasitología , ADN Protozoario/genética , Enfermedades de los Peces/epidemiología , Enfermedades de los Peces/patología , Parasitosis Hepáticas/epidemiología , Parasitosis Hepáticas/parasitología , Filogenia , Vigilancia de la PoblaciónRESUMEN
The alewife (Alosa pseudoharengus) is an anadromous herring that inhabits waters of northeastern North America. This prey species is a critical forage for piscivorous birds, mammals, and fishes in estuarine and oceanic ecosystems. During a discovery project tailored to identify potentially emerging pathogens of this species, we obtained the full genome of a novel hepadnavirus (ApHBV) from clinically normal alewives collected from the Maurice River, Great Egg Harbor River, and Delaware River in New Jersey, USA during 2015-2018. This previously undescribed hepadnavirus contained a circular DNA genome of 3146 nucleotides. Phylogenetic analysis of the polymerase protein placed this virus in the clade of metahepadnaviruses (family: Hepadnaviridae; genus: Metahepadnavirus). There was no evidence of pathology in the internal organs of infected fish and virions were not observed in liver tissues by electron microscopy. We developed a Taqman-based quantitative (qPCR) assay and screened 182 individuals collected between 2015 and 2018 and detected additional qPCR positives (n = 6). An additional complete genome was obtained in 2018 and it has 99.4% genome nucleotide identity to the first virus. Single-nucleotide polymorphisms were observed between the two genomes, including 7/9 and 12/8 synonymous vs nonsynonymous mutations across the polymerase and surface proteins, respectively. While there was no evidence that this virus was associated with disease in this species, alewives are migratory interjurisdictional fishes of management concern. Identification of microbial agents using de novo sequencing and other advanced technologies is a critical aspect of understanding disease ecology for informed population management.
Asunto(s)
Enfermedades de los Peces , Peces , Genoma Viral , Hepadnaviridae , Filogenia , Animales , Enfermedades de los Peces/virología , Hepadnaviridae/genética , Hepadnaviridae/clasificación , Hepadnaviridae/aislamiento & purificación , Peces/virología , Genómica/métodos , Infecciones por Hepadnaviridae/veterinaria , Infecciones por Hepadnaviridae/virología , New JerseyRESUMEN
Viral haemorrhagic septicaemia virus (VHSV) is a fish pathogen found throughout the Northern Hemisphere and is capable of infecting and causing mortality in numerous marine and freshwater hosts. In the coastal waters of British Columbia, Canada, the virus has been detected for 20 yr with many occurrences of mass mortalities among populations of Pacific herring Clupea pallasii (Valenciennes) and sardine Sardinops sagax as well as detections among cultured Atlantic Salmo salar and Chinook Oncorhynchus tshawytscha salmon. We compared nucleotide sequence of the full glycoprotein (G) gene coding region (1524 nt) of 63 VHSV isolates sampled during its recorded presence from 1993 to 2011 from 6 species and a total of 29 sites. Phylogenetic analysis showed that all isolates fell into sub-lineage IVa within the major VHSV genetic group IV. Of the 63 virus isolates, there were 42 unique sequences, each of which was ephemeral, being repeatedly detected at most only 1 yr after its initial detection. Multiple sequence types were revealed during single viral outbreak events, and genetic heterogeneity was observed within isolates from individual fish. Moreover, phylogenetic analysis revealed a close genetic linkage between VHSV isolates obtained from pelagic finfish species and farmed salmonids, providing evidence for virus transmission from wild to farmed fish.
Asunto(s)
Acuicultura , Septicemia Hemorrágica Viral/virología , Novirhabdovirus/genética , Salmo salar , Animales , Animales Salvajes , Colombia Británica/epidemiología , Variación Genética , Septicemia Hemorrágica Viral/epidemiología , Epidemiología Molecular , Novirhabdovirus/aislamiento & purificación , Filogenia , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa/veterinariaRESUMEN
The ontogeny and disease responses of Langerhans-like cells within lymphoid tissues of Atlantic salmon, Salmo salar, and rainbow trout, Oncorhynchus mykiss, were investigated. These cells were studied in situ with the use of two markers: the ultrastructural presence of Birbeck-like granules and immunohistochemistry with an antibody against human langerin/CD207 that cross-reacts with salmonid tissues. The appearance of Birbeck-like granules was observed in rainbow trout at 2 weeks post-hatch (PH) in the thymus and anterior kidney prior to the development of the spleen. Spleen first appeared at 3 weeks PH in both Atlantic salmon and rainbow trout, and Birbeck-like granules were observed within cells of the newly developed spleens. The cross-reactivity of langerin as seen by immunohistochemistry was not clearly observed in kidney and spleen until 9 weeks PH, when a strong cytoplasmic reaction was observed. To study langerin-positive cells in spleen and kidney during disease, microsporidial gill disease (MGD) in rainbow trout was used as a known disease model inducing a strong cell-mediated adaptive immune response. Langerin-positive cells in healthy fish were seen predominantly in the spleen, and only low numbers were present in the anterior kidney. During MGD, langerin-positive cell numbers were elevated in the anterior kidney and were significantly higher during 5, 6, and 10 weeks post-exposure (PE) compared with healthy control tissue. During MGD, the distribution of langerin-positive cells in the spleen and anterior kidney shifted from having significantly higher numbers of cells in the spleen than in the kidney in controls and at 1 and 4 weeks PE to having a similar distribution of the cells in the two organs at 2, 3, 5, and 6 weeks PE. By 10 weeks PE, significantly higher numbers of langerin-positive cells occurred in the anterior kidney compared with the spleen.
Asunto(s)
Enfermedades de los Peces/inmunología , Proteínas de Peces/inmunología , Células de Langerhans/inmunología , Microsporidiosis/inmunología , Microsporidiosis/veterinaria , Oncorhynchus mykiss/inmunología , Salmo salar/inmunología , Bazo/inmunología , Animales , Antígenos CD/inmunología , Células Cultivadas , Gránulos Citoplasmáticos/inmunología , Enfermedades de los Peces/microbiología , Humanos , Células de Langerhans/patología , Lectinas Tipo C/inmunología , Lectina de Unión a Manosa/inmunología , Microsporidios , Microsporidiosis/microbiología , Oncorhynchus mykiss/microbiología , Salmo salar/microbiología , Bazo/microbiologíaRESUMEN
The sole member of the Piscihepevirus genus (family Hepeviridae) is cutthroat trout virus (CTV) but recent metatranscriptomic studies have identified numerous fish hepevirus sequences including CTV-2. In the current study, viruses with sequences resembling both CTV and CTV-2 were isolated from salmonids in eastern and western Canada. Phylogenetic analysis of eight full genomes delineated the Canadian CTV isolates into two genotypes (CTV-1 and CTV-2) within the Piscihepevirus genus. Hepevirus genomes typically have three open reading frames but an ORF3 counterpart was not predicted in the Canadian CTV isolates. In vitro replication of a CTV-2 isolate produced cytopathic effects in the CHSE-214 cell line with similar amplification efficiency as CTV. Likewise, the morphology of the CTV-2 isolate resembled CTV, yet viral replication caused dilation of the endoplasmic reticulum lumen which was not previously observed. Controlled laboratory studies exposing sockeye (Oncorhynchus nerka), pink (O. gorbuscha), and chinook salmon (O. tshawytscha) to CTV-2 resulted in persistent infections without disease and mortality. Infected Atlantic salmon (Salmo salar) and chinook salmon served as hosts and potential reservoirs of CTV-2. The data presented herein provides the first in vitro and in vivo characterization of CTV-2 and reveals greater diversity of piscihepeviruses extending the known host range and geographic distribution of CTV viruses.
Asunto(s)
Enfermedades de los Peces/virología , Hepevirus/clasificación , Hepevirus/genética , Hepevirus/aislamiento & purificación , Animales , Canadá , Genotipo , Hepevirus/patogenicidad , Infección Persistente/virología , Filogenia , Salmo salar/virología , Salmón/virología , Trucha , Virulencia , Virus no Clasificados/clasificación , Virus no Clasificados/genética , Virus no Clasificados/aislamiento & purificación , Virus no Clasificados/patogenicidadRESUMEN
The presence of dendritic cells in fish is studied with immunohistochemistry using a commercially available antibody developed against Langerin/CD207 present in human Langerhans cells. Langerin/CD207, a protein known to be associated with the development of Birbeck granules in human and murine systems, was found to be expressed within the cytoplasm of spleen and head kidney cells of Atlantic salmon (Salmo salar) and rainbow trout (Oncorhynchus mykiss). Reactivity was also observed within a few number of cells within the head kidney of Atlantic salmon, but not observed in any other tissues examined. Immunohistochemical results showed Langerin/CD207 reactivity in the cytoplasm of cells in Atlantic salmon and rainbow trout comparable to reactivity seen in human Langerhans cells. The results in this study further corroborate the presence of dendritic cells with remarkable similarities to human Langerhans cells in the spleens and to a lesser extent in head kidney of salmonids.
Asunto(s)
Antígenos CD/inmunología , Células Dendríticas/inmunología , Oncorhynchus mykiss/inmunología , Salmo salar/inmunología , Animales , Células Dendríticas/ultraestructura , Perfilación de la Expresión Génica , Regulación de la Expresión Génica , Humanos , Células de Langerhans/inmunología , Tejido Linfoide/citología , Tejido Linfoide/inmunología , Microscopía Electrónica de Transmisión , Bazo/citología , Bazo/inmunologíaRESUMEN
: River herring populations, including Alosa pseudoharengus and Alosa aestivalis , have significantly declined as a result of anthropogenic factors throughout their range in eastern North America. To better understand the health of the species, parasite surveys were conducted in several New Jersey rivers. A novel myxozoan parasite, Myxobolus mauriensis n. sp., is described infecting the cartilage of pleural ribs in young-of-the-year fish. The parasite forms large polysporic plasmodia forming pseudocysts within the ribs, which extend into the musculature. Pathology associated with infection includes costochondritis, breaks in the rib bones, and deformed bone growth. Rupture of large pseudocysts and release of mature spores are associated with myositis, dermatitis, and peritonitis. Phylogenetic analysis reveals that M. mauriensis n. sp. occurs in a long-branching clade basal to other myxobolids, grouping with several Myxobolus species from marine fish (Myxobolus groenlandicus, Myxobolus aeglefini, and Myxobolus albi). The closest identity is to M. groenlandicus, with 83% identity based on a 1,762-bp sequence of the SSU 18S rDNA. Similarly, spore morphology, tropism for cartilage, and association with marine/brackish environments are shared in these 4 species. Mature spores of M. mauriensis n. sp. are similar to other reported myxobolids, though spores are slightly wider (12.1 ± 0.44 µm) than long (11.4 ± 0.44 µm), with a length:width relationship of 0.94 (±0.04), a feature not commonly described for other species of Myxobolus. Prevalence was studied by histology and fresh observation. In both Blueback Herring and Alewife, the highest infection prevalence occurred in the Maurice River at around 20%, and lower prevalence was found in the Great Egg Harbor River at around 5%. In the Delaware River, prevalence was about 2% in Blueback Herring, while the parasite was not detected in Alewife samples.
Asunto(s)
Enfermedades de los Peces/parasitología , Myxobolus/patogenicidad , Enfermedades Parasitarias en Animales/parasitología , Animales , Secuencia de Bases , Cartílago/parasitología , ADN/química , ADN/aislamiento & purificación , Enfermedades de los Peces/epidemiología , Enfermedades de los Peces/patología , Peces , Myxobolus/clasificación , Myxobolus/genética , New Jersey/epidemiología , Enfermedades Parasitarias en Animales/epidemiología , Enfermedades Parasitarias en Animales/patología , Filogenia , Prevalencia , Costillas/parasitología , Ríos , Alineación de Secuencia/veterinariaRESUMEN
Routine and post-exercise metabolic rates were measured for juvenile rainbow trout Oncorhynchus mykiss and brook trout Salvelinus fontinalis infected with the microsporidium gill parasite Loma salmonae under laboratory conditions. Rainbow trout increased routine and post-exercise metabolic rate in response to infection compared with controls. Brook trout, on the other hand, lowered routine metabolic rate without effecting post-exercise metabolic rate compared to controls. The result of these 2 different strategies may either reflect defense of metabolic scope or a difference in the rate of recovery of the excess post-exercise oxygen consumption between the 2 species in response to the same infection.
Asunto(s)
Metabolismo Energético/fisiología , Enfermedades de los Peces/metabolismo , Enfermedades de los Peces/microbiología , Loma , Microsporidiosis/veterinaria , Oncorhynchus mykiss , Trucha , Animales , Branquias/microbiología , Microsporidiosis/metabolismo , Consumo de Oxígeno/fisiología , Esfuerzo Físico/fisiología , Especificidad de la EspecieRESUMEN
Anadromous alewives, Alosa pseudoharengus, have experienced significant population level declines caused by factors including habitat destruction. Alewives occur in two different life histories, anadromous and landlocked forms. The landlocked alewife evolved from ancestral anadromous populations, resulting in an exclusively freshwater and phenotypically unique form. The occurrence of parasites in a host is linked to the environment, making alewives an ideal model to compare parasitology within a single species with contrasting life histories. Currently, little information exists on the presence and impacts of parasites in these fish populations; the present study sets out to better understand coccidiosis in the threatened anadromous populations and to understand how coccidian parasites compare in both life history forms. The intestinal coccidian, Goussia ameliae n. sp., was described infecting the pyloric cecum of 76% and 86% of young-of-the-year and adult anadromous alewives, respectively, from the Maurice River, New Jersey, USA. The coccidian was found in landlocked alewife populations with a prevalence of 92% and 34% in YOY and adult fish, respectively. An analysis of the small subunit 18S ribosomal RNA gene of G. ameliae from both life history forms demonstrated that the coccidian had 100% sequence identity, confirming the same parasite species in both forms. Though genetic analysis demonstrated G. ameliae to be identical, some differences were observed in sporulation and morphology of the parasite within the two populations. The sporocysts in anadromous populations were shorter and wider, and sporulation timing differed from that of landlocked fish. These differences may either be attributed to differences in the host type or to the sporulation environment. Lastly, alewives from landlocked populations were frequently co-infected with a second coccidian species in the posterior intestine, which occurred at a lower prevalence. This species, G. alosii n. sp., was described based on morphological characters of the sporulated oocysts in fresh parasitological preparations.
Asunto(s)
Células Dendríticas/inmunología , Enfermedades de los Peces/inmunología , Branquias/inmunología , Branquias/microbiología , Loma/inmunología , Microsporidiosis/inmunología , Salmón/inmunología , Animales , Citoplasma , Células Dendríticas/citología , Células Dendríticas/ultraestructura , Enfermedades de los Peces/microbiología , Loma/fisiología , Microscopía Electrónica de Transmisión , Microsporidiosis/microbiología , Salmón/microbiologíaRESUMEN
We studied the morphology and occurrence of splenic Langerhans-like (LL) cells in species representing 11 orders of ray-finned fishes, Actinopterygii. LL cells were frequent in spleen tissue of species among Cypriniformes, Esociformes, Salmoniformes, and Pleuronectiformes. These cells contained granules which resembled Birbeck granules known to occur in mammalian Langerhans cells. The ultrastructure of LL cells in Northern pike, Esox lucius, and in Atlantic halibut, Hippoglossus hippoglossus were similar to those reported in salmonids. LL cells found in cyprinids shared some characteristics with the LL cells in other Actinopterygii species, although unique structures distinguished them from the latter. They contained dense bodies within the Birbeck-like (BL) granules, a characteristic that was never observed in species outside the Cypriniformes. Two types of BL granules were characterized in cyprinid LL cells. The ultrastructure of BL granules across the species is discussed. LL cells in all Actinopterygii species demonstrated close contacts with nearby cells, characterized by adherens-like junctions. Additionally, multivesicular bodies were present within the cytoplasm and large aggregates of exosomes were observed closely associated with the plasma membrane suggesting their release from the cells. These structures are discussed in relation to mammalian dendritic cells. Macrophages found in European perch, Perca fluviatilis, blue gourami, Trichogaster trichopterus, and Atlantic halibut, Hippoglossus hippoglossus contained lysosomes and residual bodies with structures resembling Birbeck granules. These granules and cells were clearly distinct from LL cells.
Asunto(s)
Peces/anatomía & histología , Células de Langerhans/ultraestructura , Bazo/citología , Animales , Gránulos Citoplasmáticos/ultraestructura , Células de Langerhans/química , Microscopía Electrónica de Transmisión , Cuerpos Multivesiculares/ultraestructura , Bazo/ultraestructuraRESUMEN
This report is the first morphological description of cells that resemble dendritic cells, which appear to form resident populations within the spleen and anterior kidney of fish. Based on examination of three salmonid species, including, rainbow trout, brook trout, and Atlantic salmon, the cells were most abundant in the spleen, although they were always present in the anterior kidney. The cells appeared diffusely distributed, often near blood vessels of the spleen and kidney of healthy fish and within the epithelium, connective tissue, and blood vessels of rainbow trout gills with experimentally induced microsoporidial gill disease. The dendritic-like cells in this study contained granules that resemble Birbeck granules, which are considered to be morphological markers of Langerhans cells in mammals. The cells were approximately 6 mum in diameter and contained Birbeck-like (BL) granules localized near centrioles. Although the dendritic-like cells in the three salmonid species shared many similarities, morphological differences were found in the fine structure of the rod portion of the BL granules. Rainbow trout BL granules contained amorphous material, while the other salmonid species contained particulate material arranged in a square-lattice arrangement. The BL granules in the cells of Atlantic salmon had a narrow diameter and contained four layers of particulate material when sectioned longitudinally; two layers enveloped by the granule membrane and two central layers making up a central lamella, which is common in mammalian Birbeck granules.
Asunto(s)
Gránulos Citoplasmáticos/ultraestructura , Células Dendríticas/ultraestructura , Riñón/citología , Salmonidae/inmunología , Bazo/citología , Animales , Células Dendríticas/inmunología , Enfermedades de los Peces/inmunología , Riñón/inmunología , Salmonidae/anatomía & histología , Especificidad de la Especie , Bazo/inmunologíaRESUMEN
The effects of dexamethasone (dex) treatment on infections with the microsporidian parasite, Loma salmonae and the effects of dex on initiation of the adaptive immune response were investigated in rainbow trout, Oncorhynchus mykiss experimentally infected with the parasite. Dex treatment resulted in significantly higher infections with the parasite in the gills and other internal organs, suggesting that dex inhibits aspects of the innate immune response to L. salmonae; the heavier infections in the gills and organs of rainbow trout resembled infections seen in Chinook salmon. Mean xenoma counts per microscope field in the gills of fish infected with L. salmonae treated with dex or left untreated were 169 and 30, respectively. Although higher numbers of xenomas were observed in dex treated fish, the xenomas were generally smaller in size than in infected control fish. The xenomas in dex treated fish showed morphological signs of degeneration including loss and degeneration of early parasite stages, accumulation of amorphous material in xenomas, and infiltration with phagocytic cells containing degenerated parasites. The xenomas in infected untreated fish had larger xenomas with a more uniform size and contained identifiable parasite stages in the cytoplasm. According to this study, once fish have developed an adaptive immune response to the parasite by previous exposure, then fish have 100% protection to reinfection even when treated with heavy doses of dex. L. salmonae immune fish treated or untreated with dex during reinfection with the parasite developed no xenomas in the gills 6 weeks post reinfection. These results indicate that once the cellular response is primed to L. salmonae, then dex related immunosuppression does not reduce the effectiveness of the adaptive immune response.
Asunto(s)
Dexametasona/farmacología , Enfermedades de los Peces/inmunología , Inmunidad Innata/efectos de los fármacos , Loma/inmunología , Microsporidiosis/veterinaria , Oncorhynchus mykiss/inmunología , Oncorhynchus mykiss/microbiología , Animales , Antiinflamatorios/farmacología , Enfermedades de los Peces/microbiología , Enfermedades de los Peces/patología , Branquias/microbiología , Branquias/patología , Loma/efectos de los fármacos , Loma/crecimiento & desarrollo , Microscopía Electrónica de Transmisión , Microsporidiosis/inmunología , Microsporidiosis/patologíaRESUMEN
The purpose of this study was to determine adequate dose ranges and to test for side effects associated with chronic treatment of fish with indomethacin. Rainbow trout Oncorhynchus mykiss were orally treated with indomethacin at various nominal concentrations: a negative control (0 mg/kg) and low (5 mg/kg), medium (10 mg/kg), and high doses (15 mg/kg) daily for 30 d. A dose-associated mortality was observed, as cumulative mortality was 3, 13, and 33%, respectively, in the three indomethacin dose groups. No lesions were observed grossly or with histopathology in the control and low-dose treatment groups. Gross lesions were observed in the medium- and high-dose groups, including skin ulcers, abdominal distension, and necrosis of abdominal wall muscle. Histopathology of fish in the medium- and high-dosage groups revealed severe granulomatous peritonitis in which a large number of foreign body type giant cells were present around proteinaceous and plant material. The inflammatory response spread from the peritoneum through the somatic muscle to the epidermis, causing lesions within all layers of the skin. A large number of bacteria were noted within the peritonitis, observed both intracellularly and in large aggregates extracellularly. Perforations occurred within the anterior intestine, and the thick muscularis layer was replaced with inflammatory tissue. The present investigation shows that chronic indomethacin treatment produces gastrointestinal side effects in rainbow trout similar to those seen in mammals.
Asunto(s)
Antiinflamatorios no Esteroideos/toxicidad , Enfermedades de los Peces/inducido químicamente , Indometacina/toxicidad , Oncorhynchus mykiss , Animales , Relación Dosis-Respuesta a Droga , Enfermedades de los Peces/patología , Intestinos/efectos de los fármacos , Intestinos/patología , Músculo Esquelético/efectos de los fármacos , Músculo Esquelético/patología , Necrosis/inducido químicamente , Necrosis/patología , Necrosis/veterinaria , Páncreas/efectos de los fármacos , Páncreas/patología , Piel/efectos de los fármacos , Piel/patologíaRESUMEN
The sequence of host changes following the rupture of spore-laden xenomas of the microsporidian Loma salmonae during Microsporidial Gill Disease of Salmon was deduced from ultrastructural examination of the gills of naturally infected, moribund, chinook salmon from a commercial aquaculture site. The gills contained many stages of parasite development suggesting fish were chronically exposed to the parasite. Intact xenomas were generally found beneath the endothelium in arteries and arterioles and were encapsulated by a layer of collagen containing fibroblasts sometimes joined by desmosomes. Xenoma dissolution was characterized by neutrophil infiltration and loss of the xenoma plasma membrane and encapsulation. The inflammatory responses associated with ruptured xenomas ranged from acute lesions, denoted by a marked neutrophil infiltration and vascular thrombosis, to chronic lesions with a macrophage-rich infiltrate variously accompanied by neovascularization and vascular remodelling. Dendritic-like cells and plasma cells were characteristic throughout. Basement membrane damage of the primary filament epithelium and subsequent transepithelial expulsion of spores were associated with severe inflammation. An unusual previously undescribed multifocal change, in which epithelial cells invaded deeply beyond the normal boundaries of the basement membrane, affected areas of gill filament epithelium with basement membrane damage. Some neutrophils that contained L. salmonae spores, or spore polar tube, displayed morphological changes that included irregular cell shape, cytoplasmic darkening associated with an abundance of free ribosomes, lysis of neighbouring cells, and type II nuclear clefts. Fusion of apparently intact neutrophils occurred in other areas of the lesion, where close contacts between neighbouring cells were established and in some areas plasma membrane fusion occurred. Closely associated neutrophils with intact plasma membranes were observed to contain type II nuclear clefts, abundant granules and rough endoplasmic reticulum. Other neutrophils in the lesion displayed type I nuclear pockets, which is suspected to be an early stage of apoptosis.