Differential Survival of Ichthyophonus Isolates Indicates Parasite Adaptation to its Host Environment

• Published in: The Journal of parasitology 2008-10, Vol.94 (5), p.1055-1059
• Main Authors: Hershberger, P. K, Pacheco, C. A, Gregg, J. L, Purcell, M. K, LaPatra, S. E
• Format: Article
• Language: English
• Subjects: Adaptation; Adaptation, Physiological; Animal diseases; Animals; Base Sequence; Biological and medical sciences; Clupea pallasii; DNA, Protozoan - chemistry; DNA, Ribosomal - chemistry; Ecological life histories; Environment; Fish; Fish Diseases - parasitology; Fishes; Fresh Water; Freshwater; Freshwater fish; Fundamental and applied biological sciences. Psychology; Fungal infections; General aspects; General aspects and techniques. Study of several systematic groups. Models; Herring; Host-Parasite Interactions; Ichthyophonus; Invertebrates; Life Cycles-Survey; Marine; Marine fish; Marine fishes; Mesomycetozoea - classification; Mesomycetozoea - genetics; Mesomycetozoea - physiology; Mesomycetozoea Infections - parasitology; Molecular Sequence Data; Oncorhynchus mykiss; Oncorhynchus mykiss - parasitology; Parasite hosts; Parasites; Protozoa; Ribosomal DNA; RNA, Ribosomal, 18S - genetics; Salmon; Sea water; Seawater; Sequence Alignment - veterinary; Spores; Spores, Protozoan - genetics; Spores, Protozoan - physiology; Survival; Tolerances; Trout; Variance analysis
• ISSN: 0022-3395; 1937-2345
• DOI: 10.1645/GE-1553.1

In vitro viability of Ichthyophonus spp. spores in seawater and freshwater corresponded with the water type of the host from which the spores were isolated. Among Ichthyophonus spp. spores from both marine and freshwater fish hosts (Pacific herring, Clupea pallasii, and rainbow trout, Oncorhynchus mykiss, respectively), viability was significantly greater (P < 0.05) after incubation in seawater than in freshwater at all time points from 1 to 60 min after immersion; however, magnitude of the spore tolerances to water type differed with host origin. Ichthyophonus sp. adaptation to its host environment was indicated by greater seawater tolerance of spores from the marine host and greater freshwater tolerance of spores from the freshwater host. Prolonged aqueous survival of Ichthyophonus spp. spores in the absence of a host provides insight into routes of transmission, particularly among planktivorous fishes, and should be considered when designing strategies to dispose of infected fish carcasses and tissues.