title: Differential survival of Ichthyophonus isolates indicates parasite adaptation to its host environment.
abstract: 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.
authors.affiliation: Marrowstone Marine Field Station, USGS-Western Fisheries Research Center, 616 Marrowstone Point Road, Nordland, Washington 98358, USA. phershberger@usgs.gov
authors.forename: P K
authors.initials: PK
authors.lastname: Hershberger
authors.forename: C A
authors.initials: CA
authors.lastname: Pacheco
authors.forename: J L
authors.initials: JL
authors.lastname: Gregg
authors.forename: M K
authors.initials: MK
authors.lastname: Purcell
authors.forename: S E
authors.initials: SE
authors.lastname: LaPatra
mesh_terms: D000222:Adaptation, Physiological; D000818:Animals; D001483:Base Sequence; D016054:DNA, Protozoan / Q000737:chemistry; D004275:DNA, Ribosomal / Q000737:chemistry; D004777:Environment; D005393:Fish Diseases / Q000469:parasitology*; D005399:Fishes; D005618:Fresh Water; D006790:Host-Parasite Interactions; D050298:Mesomycetozoea / Q000145:classification / Q000235:genetics / Q000502:physiology*; D050738:Mesomycetozoea Infections / Q000469:parasitology*; D008969:Molecular Sequence Data; D017686:Oncorhynchus mykiss / Q000469:parasitology*; D012337:RNA, Ribosomal, 18S / Q000235:genetics; D012623:Seawater; D016415:Sequence Alignment / Q000662:veterinary; D033761:Spores, Protozoan / Q000235:genetics / Q000502:physiology
chemical_list: D016054:DNA, Protozoan; D004275:DNA, Ribosomal; D012337:RNA, Ribosomal, 18S