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Improved culture media for piscine hemoflagellates, Cryptobia and Trypanosoma (Kinetoplastida)
1Department of Zoology, University of Guelph, Ontario, Canada.
Abstract:
Increasing the Hepes buffer in minimum essential medium from 25 mM to 100 mM yielded a significantly larger number of Cryptobia salmositica. Cryptobia salmositica (pathogenic and nonpathogenic strains), Cryptobia bullocki, and Trypanosoma danilewskyi did not multiply either in heat-inactivated trout plasma (< or =25%) or in less than 10% fresh trout plasma. Both strains of C. salmositica multiplied better in 10% fresh trout plasma than in 25% heat-inactivated fetal bovine serum. In contrast, C. bullocki and T. danilewskyi multiplied better in 25% fetal bovine serum; 10% fetal bovine serum did not significantly reduce multiplication of C. bullocki. The nonpathogenic vaccine strain of C. salmositica cultured in 10% fresh trout plasma still protected rainbow trout from high parasitemia when challenged with the pathogen.
Insights
Increasing Hepes buffer concentration in cell culture media significantly enhanced Cryptobia salmositica growth. A nonpathogenic C. salmositica strain cultured in trout plasma also provided protection against the pathogen in rainbow trout.
Area of Science:
- Parasitology
- Aquatic Animal Health
- Cell Culture
Background:
- Cryptobia salmositica is an important parasite affecting fish health.
- Optimizing culture conditions is crucial for studying parasitic protozoa like Cryptobia and Trypanosoma.
- Understanding host-parasite interactions requires effective in vitro cultivation methods.
Purpose of the Study:
- To investigate the effects of Hepes buffer concentration on Cryptobia salmositica growth.
- To determine optimal plasma concentrations for the in vitro cultivation of fish-associated protozoa.
- To evaluate the efficacy of a cultured nonpathogenic Cryptobia salmositica strain as a vaccine.
Main Methods:
- Culturing Cryptobia salmositica, Cryptobia bullocki, and Trypanosoma danilewskyi in varying concentrations of Hepes buffer and trout plasma.
- Assessing parasite multiplication rates in different media compositions, including heat-inactivated and fresh plasma.
- Challenging rainbow trout with a pathogenic strain after vaccination with a cultured nonpathogenic strain.
Main Results:
- Higher Hepes buffer concentrations (100 mM) in minimum essential medium significantly increased Cryptobia salmositica numbers.
- Both strains of C. salmositica multiplied better in 10% fresh trout plasma compared to heat-inactivated fetal bovine serum.
- Cryptobia bullocki and Trypanosoma danilewskyi showed better multiplication in 25% fetal bovine serum.
- The nonpathogenic C. salmositica strain, cultured in 10% fresh trout plasma, conferred protection to rainbow trout against high parasitemia.
Conclusions:
- Hepes buffer concentration is a critical factor for optimizing Cryptobia salmositica in vitro culture.
- Trout plasma supports the growth of C. salmositica, while fetal bovine serum is more suitable for C. bullocki and T. danilewskyi.
- In vitro cultured nonpathogenic Cryptobia salmositica demonstrates potential as a vaccine for rainbow trout.
