Optimization of a Plaque Neutralization Test (PNT) to identify the exposure history of Pacific Herring to viral hemorrhagic septicemia virus (VHSV)

Journal of Aquatic Animal Health
By: , and 

Links

Abstract

Methods for a plaque neutralization test (PNT) were optimized for the detection and quantification of viral hemorrhagic septicemia virus (VHSV) neutralizing activity in the plasma of Pacific Herring Clupea pallasii. The PNT was complement dependent, as neutralizing activity was attenuated by heat inactivation; further, neutralizing activity was mostly restored by the addition of exogenous complement from specific-pathogen-free Pacific Herring. Optimal methods included the overnight incubation of VHSV aliquots in serial dilutions (starting at 1:16) of whole test plasma containing endogenous complement. The resulting viral titers were then enumerated using a viral plaque assay in 96-well microplates. Serum neutralizing activity was virus-specific as plasma from viral hemorrhagic septicemia (VHS) survivors demonstrated only negligible reactivity to infectious hematopoietic necrosis virus, a closely related rhabdovirus. Among Pacific Herring that survived VHSV exposure, neutralizing activity was detected in the plasma as early as 37 d postexposure and peaked at approximately 64 d postexposure. The onset of neutralizing activity was slightly delayed in fish reared at 7.4°C relative to those in warmer temperatures (9.9°C and 13.1°C); however, neutralizing activity persisted for at least 345 d postexposure in all temperature treatments. It is anticipated that this novel ability to assess VHSV neutralizing activity in Pacific Herring will enable retrospective comparisons between prior VHS infections and year-class recruitment failures. Additionally, the optimized PNT could be employed as a forecasting tool capable of identifying the potential for future VHS epizootics in wild Pacific Herring populations.

Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Optimization of a Plaque Neutralization Test (PNT) to identify the exposure history of Pacific Herring to viral hemorrhagic septicemia virus (VHSV)
Series title Journal of Aquatic Animal Health
DOI 10.1080/08997659.2017.1285369
Volume 29
Issue 2
Year Published 2017
Language English
Publisher Taylor & Francis
Contributing office(s) Western Fisheries Research Center
Description 9 p.
First page 74
Last page 82