Factors controlling the early stages of viral haemorrhagic septicaemia epizootics: Low exposure levels, virus amplification and fish-to-fish transmission

Journal of Fish Diseases
By: , and 

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Abstract

Viral haemorrhagic septicaemia virus, Genogroup IVa (VHSV), was highly infectious to Pacific herring, Clupea pallasii (Valenciennes), even at exposure doses occurring below the threshold of sensitivity for a standard viral plaque assay; however, further progression of the disease to a population‐level epizootic required viral amplification and effective fish‐to‐fish transmission. Among groups of herring injected with VHSV, the prevalence of infection was dose‐dependent, ranging from 100%, 75% and 38% after exposure to 19, 0.7 and 0.07 plaque‐forming units (PFU)/fish, respectively. Among Pacific herring exposed to waterborne VHSV (140 PFU mL−1), the prevalence of infection, geometric mean viral tissue titre and cumulative mortality were greater among cohabitated herring than among cohorts that were held in individual aquaria, where fish‐to‐fish transmission was prevented. Fish‐to‐fish transmission among cohabitated herring probably occurred via exposure to shed virus which peaked at 680 PFU mL−1; shed virus was not detected in the tank water from any isolated individuals. The results provide insights into mechanisms that initiate epizootic cascades in populations of wild herring and have implications for the design of VHSV surveys in wild fish populations.

Publication type Article
Publication Subtype Journal Article
Title Factors controlling the early stages of viral haemorrhagic septicaemia epizootics: Low exposure levels, virus amplification and fish-to-fish transmission
Series title Journal of Fish Diseases
DOI 10.1111/j.1365-2761.2011.01305.x
Volume 34
Issue 12
Year Published 2011
Language English
Publisher Wiley
Description 7 p.
First page 893
Last page 899
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