Physiological and hematological changes in Chum Salmon artificially infected with Erythrocytic Necrosis virus

Journal of Aquatic Animal Health
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Abstract

Chum salmon Oncorhynchus keta were injected with erythrocytic necrosis virus (ENV) to study the physiological and hematological consequences of ENV infection. Infected and control fish were held in pathogen-free seawater and sampled for 5 weeks. Physiological tests included measures of plasma cortisol, glucose, protein, and osmolality; blood lactic acid; and liver glycogen. In general, ENV-infected fish had lower plasma glucose and blood lactic acid, and higher liver glycogen concentrations than did control fish. Hematological tests included red and white blood cell (RBC and WBC) counts, hematocrit, measurement of blood hemoglobin concentration, and a determination of erythrocyte fragility. Infected fish had lower RBC counts, hematocrits, and hemoglobin concentrations; higher WBC counts; and less fragile erythrocytes than did control fish. The hematology data indicated that erythrocytes of infected fish had higher mean corpuscular volume, depressed mean corpuscular hemoglobin concentration, and slightly lower mean corpuscular hemoglobin. Erythrocytic inclusions were observed in the cytoplasm of RBCs from infected fish. The infection progressed steadily through week 4, after which the fish appeared to begin recovering. In a second study, fish were infected with ENV for 3 weeks, and recovery from a stress challenge test was measured. Plasma glucose concentrations and osmclality were higher in infected fish, whereas plasma cortisol and blood lactate were only slightly elevated. These studies indicate that chum salmon withstood the effects of ENV infection without in-eversible physiological consequences. However, when subjected to a stress challenge test, infected fish recovered more slowly than control fish and had increased osmoregulatory difficulties.

Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Physiological and hematological changes in Chum Salmon artificially infected with Erythrocytic Necrosis virus
Series title Journal of Aquatic Animal Health
DOI 10.1577/1548-8667(1992)004<0048:PAHCIC>2.3.CO;2
Volume 4
Issue 1
Year Published 1992
Language English
Publisher Taylor & Francis
Contributing office(s) Western Fisheries Research Center
Description 10 p.
First page 48
Last page 57