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Kinetics of viral load and erythrocytic inclusion body formation in pacific herring artificially infected with erythrocytic necrosis virus

Journal of Aquatic Animal Health

By:
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DOI: 10.1080/08997659.2012.676592

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Abstract

Viral erythrocytic necrosis (VEN) is a condition that affects marine and anadromous fish species, including herrings and salmonids, in the Atlantic and Pacific oceans. Infection is frequently associated with severe anemia and causes episodic mortality among wild and hatchery fish when accompanied by additional stressors; VEN can be presumptively diagnosed by (1) light microscopic identification of a single characteristic-a round, magenta-colored, 0.8-μm-diameter inclusion body (IB) within the cytoplasm of erythrocytes and their precursors on Giemsa-stained blood films; or (2) observation (via transmission electron microscopy [TEM]) of the causative iridovirus, erythrocytic necrosis virus (ENV), within erythrocytes or their precursors. To better understand the kinetics of VEN, specific-pathogen-free Pacific herring Clupea pallasii were infected with ENV by intraperitoneal injection. At 1, 4, 7, 10, 14, 21, and 28 d postexposure, samples of blood, spleen, and kidney were collected and assessed (1) via light microscopy for the number of intracytoplasmic IBs in blood smears and (2) via TEM for the number of virions within erythrocytes. The mean prevalence of intracytoplasmic IBs in the blood cells increased from 0% at 0-4 d postexposure to 94% at 28 d postexposure. Viral load within circulating red blood cells peaked at 7 d postexposure, fell slightly, and then reached a plateau. However, blood cells observed within the kidney and spleen tissues demonstrated high levels of ENV between 14 and 28 d postexposure. The results indicate that the viral load within erythrocytes does not correlate well with IB prevalence and that the virus can persist in infected fish for more than 28 d.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Kinetics of viral load and erythrocytic inclusion body formation in pacific herring artificially infected with erythrocytic necrosis virus
Series title:
Journal of Aquatic Animal Health
DOI:
10.1080/08997659.2012.676592
Volume
24
Issue:
3
Year Published:
2012
Language:
English
Publisher:
Taylor & Francis
Publisher location:
Philadelphia, PA
Contributing office(s):
Western Fisheries Research Center
Description:
6 p.
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
Larger Work Title:
Journal of Aquatic Animal Health
First page:
195
Last page:
200
Country:
United States