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Description of the Microsporidian Parasite, Heterosporis sutherlandae n. sp., Infecting Fish in the Great Lakes Region, USA.

Phelps NB, Mor SK, Armién AG, Pelican KM, Goyal SM - PLoS ONE (2015)

Bottom Line: A unique species of Heterosporis was identified, demonstrating less than 96% sequence identity to other published Heterosporis sp. on the basis of partial rRNA gene sequence analysis.Heterosporis sutherlandae n. sp. (formerly Heterosporis sp.) was identified in yellow perch (Perca flavescens), northern pike (Esox lucius) and walleye (Sander vitreus) from inland lakes in Minnesota and Wisconsin.Previous research suggests this species may be even more widespread in the Great Lakes region and should be reexamined using molecular techniques to better understand the distribution of this novel species.

View Article: PubMed Central - PubMed

Affiliation: Veterinary Diagnostic Laboratory, College of Veterinary Medicine, University of Minnesota, 1333 Gortner Avenue, Saint Paul, Minnesota, 55108, United States of America; Veterinary Population Medicine Department, College of Veterinary Medicine, University of Minnesota, 1365 Gortner Avenue, Saint Paul, Minnesota, 55108, United States of America.

ABSTRACT
Heterosporosis is an increasingly important microsporidian disease worldwide, impacting wild and farmed raised fishes in both marine and freshwater environments. A previously undescribed species (Heterosporis sp.), with widespread distribution in the Great Lakes region, was the subject of this study. Three angler-caught fish were submitted to the Minnesota Veterinary Diagnostic Laboratory from 2009-2010 with lesions caused by intracellular proliferation of parasitic spores, resulting in destruction and eventual widespread necrosis of the host skeletal muscles. Mature ovoid (5.8 x 3.5 μm) spores of a microsporidian parasite, consistent with the genus Heterosporis, were observed by light and electron microscopy. Molecular identification was performed using primer walking to obtain a near-complete rRNA gene sequence (~3,600 bp). A unique species of Heterosporis was identified, demonstrating less than 96% sequence identity to other published Heterosporis sp. on the basis of partial rRNA gene sequence analysis. Heterosporis sutherlandae n. sp. (formerly Heterosporis sp.) was identified in yellow perch (Perca flavescens), northern pike (Esox lucius) and walleye (Sander vitreus) from inland lakes in Minnesota and Wisconsin. Previous research suggests this species may be even more widespread in the Great Lakes region and should be reexamined using molecular techniques to better understand the distribution of this novel species.

No MeSH data available.


Related in: MedlinePlus

A) Fresh preparation of microsporidia-infected fish. Arrow indicates a spore of Heterosporis sutherlandae n. sp. Arrowhead shows a sporophorous vesicle with several spores. B) Widespread muscle destruction due to H. sutherlandae. Mature spores have replaced muscle cells and are surrounded by loose fibrous tissue (asterisk). The wide arrow indicates a large sporophorocyst containing sporoblast and spores. The narrow arrow shows ruptured sporophorocyst vesicles. Tissue embedded in paraffin and stained with PAS. Scale bar is 100 μm. Inset: Giemsa stained preparation showing a detail of the wall of a sporophorocyst (wide arrow) and the wall of a sporophororous vesicle (arrowhead). Scale bar is 25 μm. C) Sporophorocysts (asterisk) within skeletal muscle cells (sm). Arrows indicate the sporophorocystic wall. Tissue embedded in resin and stained with Toluidine blue. Scale bar is 12 μm.
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pone.0132027.g002: A) Fresh preparation of microsporidia-infected fish. Arrow indicates a spore of Heterosporis sutherlandae n. sp. Arrowhead shows a sporophorous vesicle with several spores. B) Widespread muscle destruction due to H. sutherlandae. Mature spores have replaced muscle cells and are surrounded by loose fibrous tissue (asterisk). The wide arrow indicates a large sporophorocyst containing sporoblast and spores. The narrow arrow shows ruptured sporophorocyst vesicles. Tissue embedded in paraffin and stained with PAS. Scale bar is 100 μm. Inset: Giemsa stained preparation showing a detail of the wall of a sporophorocyst (wide arrow) and the wall of a sporophororous vesicle (arrowhead). Scale bar is 25 μm. C) Sporophorocysts (asterisk) within skeletal muscle cells (sm). Arrows indicate the sporophorocystic wall. Tissue embedded in resin and stained with Toluidine blue. Scale bar is 12 μm.

Mentions: Gross lesions were characterized as multifocal to coalescing to locally extensive necrosis of skeletal muscle tissue (Fig 1A and 1B). The distribution and severity of Heterosporis-induced lesions varied among samples. In fresh preparations, spores were oval to pyriform with an eccentrically located posterior vacuole (Fig 2A) and measured 5.8 ± 0.5 μm (4.8–6.3 μm) × 3.45 ± 0.15 (3.2–3.6 μm). Occasionally, spores were inside sporophorous vesicles, typically containing 4–8 spores (Fig 2A). The muscle fibers were distended and sarcoplasm and myofibrils were replaced with large numbers of Heterosporis spores at different stages of development. In areas of high spore concentration, a majority of the skeletal muscle cells were replaced by the parasites (Fig 2B). In less affected areas of the skeletal muscle, sporophorocysts containing developmental stages were found (Fig 2B). There was a multifocal granulomatous inflammatory infiltration expanding the interstitium of the skeletal musculature. Macrophages were distended and contained numerous developing spores within phagocytic vacuoles. A mild amount of fibrous tissue replaced necrotic skeletal muscles fibers. Despite the advanced infection of skeletal muscle tissue, no spores were observed in histological sections of kidney, liver, spleen, brain, intestine, and heart. In addition to H&E, Giemsa and PAS were also demonstrated to have diagnostic value since parasites and cyst membranes were clearly identified when stained (Fig 2B and inset).


Description of the Microsporidian Parasite, Heterosporis sutherlandae n. sp., Infecting Fish in the Great Lakes Region, USA.

Phelps NB, Mor SK, Armién AG, Pelican KM, Goyal SM - PLoS ONE (2015)

A) Fresh preparation of microsporidia-infected fish. Arrow indicates a spore of Heterosporis sutherlandae n. sp. Arrowhead shows a sporophorous vesicle with several spores. B) Widespread muscle destruction due to H. sutherlandae. Mature spores have replaced muscle cells and are surrounded by loose fibrous tissue (asterisk). The wide arrow indicates a large sporophorocyst containing sporoblast and spores. The narrow arrow shows ruptured sporophorocyst vesicles. Tissue embedded in paraffin and stained with PAS. Scale bar is 100 μm. Inset: Giemsa stained preparation showing a detail of the wall of a sporophorocyst (wide arrow) and the wall of a sporophororous vesicle (arrowhead). Scale bar is 25 μm. C) Sporophorocysts (asterisk) within skeletal muscle cells (sm). Arrows indicate the sporophorocystic wall. Tissue embedded in resin and stained with Toluidine blue. Scale bar is 12 μm.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4526549&req=5

pone.0132027.g002: A) Fresh preparation of microsporidia-infected fish. Arrow indicates a spore of Heterosporis sutherlandae n. sp. Arrowhead shows a sporophorous vesicle with several spores. B) Widespread muscle destruction due to H. sutherlandae. Mature spores have replaced muscle cells and are surrounded by loose fibrous tissue (asterisk). The wide arrow indicates a large sporophorocyst containing sporoblast and spores. The narrow arrow shows ruptured sporophorocyst vesicles. Tissue embedded in paraffin and stained with PAS. Scale bar is 100 μm. Inset: Giemsa stained preparation showing a detail of the wall of a sporophorocyst (wide arrow) and the wall of a sporophororous vesicle (arrowhead). Scale bar is 25 μm. C) Sporophorocysts (asterisk) within skeletal muscle cells (sm). Arrows indicate the sporophorocystic wall. Tissue embedded in resin and stained with Toluidine blue. Scale bar is 12 μm.
Mentions: Gross lesions were characterized as multifocal to coalescing to locally extensive necrosis of skeletal muscle tissue (Fig 1A and 1B). The distribution and severity of Heterosporis-induced lesions varied among samples. In fresh preparations, spores were oval to pyriform with an eccentrically located posterior vacuole (Fig 2A) and measured 5.8 ± 0.5 μm (4.8–6.3 μm) × 3.45 ± 0.15 (3.2–3.6 μm). Occasionally, spores were inside sporophorous vesicles, typically containing 4–8 spores (Fig 2A). The muscle fibers were distended and sarcoplasm and myofibrils were replaced with large numbers of Heterosporis spores at different stages of development. In areas of high spore concentration, a majority of the skeletal muscle cells were replaced by the parasites (Fig 2B). In less affected areas of the skeletal muscle, sporophorocysts containing developmental stages were found (Fig 2B). There was a multifocal granulomatous inflammatory infiltration expanding the interstitium of the skeletal musculature. Macrophages were distended and contained numerous developing spores within phagocytic vacuoles. A mild amount of fibrous tissue replaced necrotic skeletal muscles fibers. Despite the advanced infection of skeletal muscle tissue, no spores were observed in histological sections of kidney, liver, spleen, brain, intestine, and heart. In addition to H&E, Giemsa and PAS were also demonstrated to have diagnostic value since parasites and cyst membranes were clearly identified when stained (Fig 2B and inset).

Bottom Line: A unique species of Heterosporis was identified, demonstrating less than 96% sequence identity to other published Heterosporis sp. on the basis of partial rRNA gene sequence analysis.Heterosporis sutherlandae n. sp. (formerly Heterosporis sp.) was identified in yellow perch (Perca flavescens), northern pike (Esox lucius) and walleye (Sander vitreus) from inland lakes in Minnesota and Wisconsin.Previous research suggests this species may be even more widespread in the Great Lakes region and should be reexamined using molecular techniques to better understand the distribution of this novel species.

View Article: PubMed Central - PubMed

Affiliation: Veterinary Diagnostic Laboratory, College of Veterinary Medicine, University of Minnesota, 1333 Gortner Avenue, Saint Paul, Minnesota, 55108, United States of America; Veterinary Population Medicine Department, College of Veterinary Medicine, University of Minnesota, 1365 Gortner Avenue, Saint Paul, Minnesota, 55108, United States of America.

ABSTRACT
Heterosporosis is an increasingly important microsporidian disease worldwide, impacting wild and farmed raised fishes in both marine and freshwater environments. A previously undescribed species (Heterosporis sp.), with widespread distribution in the Great Lakes region, was the subject of this study. Three angler-caught fish were submitted to the Minnesota Veterinary Diagnostic Laboratory from 2009-2010 with lesions caused by intracellular proliferation of parasitic spores, resulting in destruction and eventual widespread necrosis of the host skeletal muscles. Mature ovoid (5.8 x 3.5 μm) spores of a microsporidian parasite, consistent with the genus Heterosporis, were observed by light and electron microscopy. Molecular identification was performed using primer walking to obtain a near-complete rRNA gene sequence (~3,600 bp). A unique species of Heterosporis was identified, demonstrating less than 96% sequence identity to other published Heterosporis sp. on the basis of partial rRNA gene sequence analysis. Heterosporis sutherlandae n. sp. (formerly Heterosporis sp.) was identified in yellow perch (Perca flavescens), northern pike (Esox lucius) and walleye (Sander vitreus) from inland lakes in Minnesota and Wisconsin. Previous research suggests this species may be even more widespread in the Great Lakes region and should be reexamined using molecular techniques to better understand the distribution of this novel species.

No MeSH data available.


Related in: MedlinePlus