DAO 122:213-221 (2017)  -  DOI: https://doi.org/10.3354/dao03076

Transmission potential of infectious hematopoietic necrosis virus in APEX-IHN®-vaccinated Atlantic salmon

Amy Long1,*, Jon Richard1, Laura Hawley1, Scott E. LaPatra2, Kyle A. Garver1

1Fisheries and Oceans Canada, Pacific Biological Station, Nanaimo, BC V9T 6N7, Canada
2Clear Springs Foods Inc., Research Division, PO Box 712 Buhl, ID 83316, USA
*Corresponding author:

ABSTRACT: Infectious hematopoietic necrosis virus (IHNV) outbreaks have had a significant negative impact on Atlantic salmon Salmo salar production in British Columbia, Canada, since the first outbreak was reported in 1992. In 2005, the APEX-IHN® vaccine was approved for use in Canada for prevention of IHN. The vaccine was proven to be safe and efficacious prior to approval; however, it is unknown as to whether APEX-IHN®-vaccinated Atlantic salmon infected with IHNV can support replication and virus shedding in sufficient quantities to provide an infectious dose to a nearby susceptible host. To determine whether vaccinated, infected fish are able to transmit an infectious dose of IHNV, vaccinated Atlantic salmon were injected with IHNV (104 plaque-forming units per fish) and cohabitated with either naïve Atlantic salmon or naïve sockeye salmon Oncorhynchus nerka. APEX-IHN®-vaccinated fish were significantly protected against IHNV with mortality occurring in only 2.6% of the population as opposed to 97% in unvaccinated controls. Vaccination in IHNV-infected Atlantic salmon completely abolished disease transmission to cohabitating naïve sockeye salmon and reduced virus spread among cohabitating naïve Atlantic salmon. At 7 mo post-vaccination, IHNV-neutralizing antibodies were detected in nearly all vaccinated fish (94%) with similar titer occurring between vaccinated, infected fish and vaccinated, uninfected fish, indicating APEX-IHN® vaccination induces a robust seroconversion response. Taken together, these results demonstrate that vaccination greatly reduces the infectious load and potential for IHNV transmission. As such, APEX-IHN® should be included in fish health management strategies when culturing Atlantic salmon in IHNV endemic areas.


KEY WORDS: APEX-IHN® vaccine · Infectious hematopoietic necrosis virus · IHNV · Atlantic salmon · Sockeye salmon


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Cite this article as: Long A, Richard J, Hawley L, LaPatra SE, Garver KA (2017) Transmission potential of infectious hematopoietic necrosis virus in APEX-IHN®-vaccinated Atlantic salmon. Dis Aquat Org 122:213-221. https://doi.org/10.3354/dao03076

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