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

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 Export citation Share:    Facebook - - linkedIn