Article: Experimental Challenge of Atlantic Cod (Gadus morhua) with a Brucella pinnipedialis Strain from Hooded Seal (Cystophora cristata)
Authors: * Ingebjørg Helena Nymo, * Marit Seppola, * Sascha Al Dahouk, * Kathrine Ryvold Bakkemo, * María Pilar Jiménez de Bagüés, * Jacques Godfroid, * Anett Kristin Larsen Journal: PLoS ONE 11(7): e0159272. doi:10.1371/journal.pone.0159272 Available here: http://journals.plos.org/plosone/article?id=10.1371%2Fjournal.pone.0159272 Abstract: Pathology has not been observed in true seals infected with Brucella pinnipedialis. A lack of intracellular survival and multiplication of B. pinnipedialis in hooded seal (Cystophora cristata) macrophages in vitro indicates a lack of chronic infection in hooded seals. Both epidemiology and bacteriological patterns in the hooded seal point to a transient infection of environmental origin, possibly through the food chain. To analyse the potential role of fish in the transmission of B. pinnipedialis, Atlantic cod (Gadus morhua) were injected intraperitoneally with 7.5 x 107bacteria of a hooded seal field isolate. Samples of blood, liver, spleen, muscle, heart, head kidney, female gonads and feces were collected on days 1, 7, 14 and 28 post infection to assess the bacterial load, and to determine the expression of immune genes and the specific antibody response. Challenged fish showed an extended period of bacteremia through day 14 and viable bacteria were observed in all organs sampled, except muscle, until day 28. Neither gross lesions nor mortality were recorded. Anti-Brucella antibodies were detected from day 14 onwards and the expression of hepcidin, cathelicidin, interleukin (IL)-1β, IL-10, and interferon (IFN)-γ genes were significantly increased in spleen at day 1 and 28. Primary mononuclear cells isolated from head kidneys of Atlantic cod were exposed to B. pinnipedialis reference (NCTC 12890) and hooded seal (17a-1) strain. Both bacterial strains invaded mononuclear cells and survived intracellularly without any major reduction in bacterial counts for at least 48 hours. Our study shows that the B. pinnipedialis strain isolated from hooded seal survives in Atlantic cod, and suggests that Atlantic cod could play a role in the transmission of B.pinnipedialis to hooded seals in the wild. Ingebjorg Helena Nymo DVM, PhD Post Doctoral Researcher Research Group of Arctic Infection Biology Department of Arctic and Marine Biology Faculty of Biosciences, Fisheries and Economics University of Troms? - The Arctic University of Norway Phone: +47 918 38 421 / mail: [email protected]<mailto:[email protected]><mailto:[email protected]> https://uit.no/om/enhet/ansatte/person?p_document_id=360200&p_dimension_id=88165
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