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In vitro characteristics of the microsporidian: Enterocytozoon salmonis
J Wongtavatchai1, P A Conrad, R P Hedrick
1Department of Medicine and Epidemiology, University of California, Davis 95616, USA.
Abstract:
Enterocytozoon salmonis, as intranuclear microsporidian of salmonid fish, was propagated in vitro using chinook salmon mononuclear leukocytes. Characteristic morphology and infectivity of the cultured parasites were evaluated to determine the effect of in vitro maintenance and passage on the parasites. Cultured parasites developed through several stages from meronts to infectious spores. Parasites obtained from in vitro passages tested up to the 17th subculture, retained their morphological characteristics and pathogenicity for chinook salmon (Oncorhynchus tshawytscha). The disease induced by experimental infections with parasites from in vitro cultures was identical to that observed in naturally infected chinook salmon. An examination of supernatants obtained from the infected cultures revealed evidence of soluble factor(s) produced by E. salmonis-infected cells that stimulated uninfected target cells in vitro. This observation may explain in part the proliferative disease of hematopoietic tissues which characterizes the disease in infected chinook salmon.
Insights
Chinook salmon (Oncorhynchus tshawytscha) mononuclear leukocytes successfully propagated Enterocytozoon salmonis in vitro. The cultured parasite retained its morphology and pathogenicity through 17 passages, mimicking natural infections.
Area of Science:
- * Aquatic animal health
- * Fish pathology
- * Microsporidian biology
Background:
- * Enterocytozoon salmonis is an intranuclear microsporidian pathogen affecting salmonid fish.
- * Understanding its in vitro behavior is crucial for disease research and management.
Purpose of the Study:
- * To propagate Enterocytozoon salmonis in vitro using chinook salmon cells.
- * To evaluate the effects of in vitro maintenance and passage on parasite morphology and infectivity.
- * To investigate potential soluble factors produced by infected cells.
Main Methods:
- * In vitro propagation of E. salmonis using chinook salmon mononuclear leukocytes.
- * Morphological and infectivity assessments of cultured parasites through serial passages (up to 17th subculture).
- * Experimental infections in chinook salmon to compare in vitro-derived and naturally occurring diseases.
- * Analysis of cell culture supernatants for soluble factors.
Main Results:
- * E. salmonis was successfully propagated in vitro, progressing through developmental stages to infectious spores.
- * Cultured parasites maintained characteristic morphology and pathogenicity through 17 subcultures.
- * In vitro-derived infections mirrored the disease observed in naturally infected chinook salmon.
- * Supernatants from infected cultures contained soluble factors that stimulated uninfected cells.
Conclusions:
- * In vitro culture is a viable method for maintaining E. salmonis infectivity and morphology.
- * The study provides a model for investigating E. salmonis pathogenesis.
- * Soluble factors from infected cells may contribute to the proliferative hematopoietic disease observed in chinook salmon.