28th ANNUAL EASTERN FISH HEALTH WORKSHOP April 21-25, 2003 Relative Resistance Of Pacific Salmon To Infectious Salmon Anemia Virus  Jill B. Rolland and James R. Winton Western Fisheries Research Center, Biological Resources Discipline, United States Geological Survey, 6505 NE 65th St., Seattle, Washington 98115 The aim of this study was to determine the susceptibilities of Pacific salmonid species to Infectious Salmon Anemia virus (ISAv) compared to Atlantic salmon (Salmo salar).  Chum (Oncorhynchus keta), steelhead (O. mykiss), chinook (O. tsawytscha), coho (O. kisutch) and Atlantic salmon were distributed into duplicate tanks of 25 fish per species per ISAv dosage.  In Experiment 1, groups were injected intraperitoneally (ip.) with a high (108 TCID50 ml-1), medium (106 TCID50 ml-1) or low (104 TCID50 ml-1) dosage of ISAv (Bremnes, Norway).  Experiment 2 was a high dosage (108 TCID50 ml-1) ip. challenge of all species, except chum salmon, with ISAV of either the New Brunswick, Canada or the Bremnes, Norway strain.  The cumulative mortality of Atlantic salmon in Experiment 1 was 12% in the high dosage group, 20% in the medium dosage group and 16% in the low dosage group.  The average cumulative mortality of Atlantic salmon in Experiment 2 was 98%.  No ISAv-related mortality occurred among any of the Oncorhynchus spp. in either experiment although ISAv was detected in random samplings of all species except Chinook salmon, suggesting that infection is possible.  The results indicated that Oncorhynchus spp. were relatively resistant to ISAv infection.  However, the potential for ISAv to affect Oncorhynchus spp. should not be ignored because this virus belongs to the Orthomyxoviridae, a highly adaptive family of viruses that includes the influenza virus. Return to 28th Annual Eastern Fish Health Workshop Return to Leetown Science Center Home Page