DAO 97:155-165 (2011)  -  DOI: https://doi.org/10.3354/dao02414

Vector potential of the salmon louse Lepeophtheirus salmonis in the transmission of infectious haematopoietic necrosis virus (IHNV)

E. Jakob1,2,*, D. E. Barker2, K. A. Garver1

1Fisheries & Oceans Canada, Pacific Biological Station, 3190 Hammond Bay Road, Nanaimo, British Columbia V9T 6N7, Canada
2Fisheries & Aquaculture Department, Vancouver Island University, 900 Fifth Street, Nanaimo, British Columbia V9R 5S5, Canada

ABSTRACT: To better understand the role of vector transmission of aquatic viruses, we established an in vivo virus−parasite challenge specifically to address (1) whether Lepeophtheirus salmonis can acquire infectious haematopoietic necrosis virus (IHNV) after water bath exposure or via parasitizing infected Atlantic salmon Salmo salar and if so, define the duration of this association and (2) whether L. salmonis can transmit IHNV to naïve Atlantic salmon and whether this transmission requires attachment to the host. Salmon lice which were water bath-exposed to 1 × 105 plaque-forming units (pfu) ml−1 of IHNV for 1 h acquired the virus (2.1 × 104 pfu g−1) and remained IHNV-positive for 24 h post exposure. After parasitizing IHNV-infected hosts (viral titer in fish mucus 3.3 × 104 pfu ml−1) salmon lice acquired IHNV (3.4 × 103 pfu g−1) and remained virus-positive for 12 h. IHNV-positive salmon lice generated through water bath exposure or after parasitizing infected Atlantic salmon successfully transmitted IHNV, resulting in 76.5 and 86.6% of the exposed Atlantic salmon testing positive for IHNV, respectively. In a second experiment, only salmon lice that became IHNV-positive through water bath exposure transmitted IHNV to 20% of the naïve fish, and no virus was transmitted when IHNV-infected salmon lice were cohabitated but restrained from attaching to naïve fish. Under laboratory conditions, adult L. salmonis can acquire IHNV and transmit it to naïve Atlantic salmon through parasitism. However, the ephemeral association of IHNV with L. salmonis indicates that the salmon louse act as a mechanical rather than a biological vector or reservoir.


KEY WORDS: Sea lice · Lepeophteirus salmonis · Infectious heamatopoietic necrosis virus (IHNV) · Disease vector · Virus transmission · Atlantic salmon · Salmo salar


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Cite this article as: Jakob E, Barker DE, Garver KA (2011) Vector potential of the salmon louse Lepeophtheirus salmonis in the transmission of infectious haematopoietic necrosis virus (IHNV). Dis Aquat Org 97:155-165. https://doi.org/10.3354/dao02414

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