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Molecular cloning and expression analysis of tumour necrosis factor-alpha in amoebic gill disease (AGD)-affected Atlantic salmon (Salmo salar L.)
journal contributionposted on 2023-05-16, 20:22 authored by Morrison, RN, Zou, J, Secombes, CJ, Scapigliati, G, Mark AdamsMark Adams, Barbara NowakBarbara Nowak
Tumour necrosis factor-alpha (TNF-Î±) is a key mediator of inflammation during amoebiasis of humans and mice. Atlantic salmon (Salmo salar L.) are also susceptible to infection by amoebae (Neoparamoeba spp.), inflicting a condition known as amoebic gill disease (AGD). Here, the role of TNF-Î± in AGD-pathogenesis was examined. Two Atlantic salmon TNF-Î± transcripts designated TNF-Î±1 and TNF-Î±2 together with their respective genes were cloned and sequenced. TNF-Î±1 is 1379 bp and consists of a 738 bp open reading frame (ORF) translating into a predicted protein of 246 amino acids. TNF-Î±2 is 1412 bp containing an ORF and translated protein the same lengths as TNF-Î±1. An anti-rainbow trout TNF-Î± polyclonal antibody that bound recombinant Atlantic salmon TNF-Î±1 and TNF-Î±2 was used to detect constitutive and inducible expression of TNF-Î± in various tissues. The anti-TNF-Î± antibody bound to a TNF-like protein â‰ˆ60 kDa that was constitutively expressed in a number of tissues in healthy Atlantic salmon. However, this protein was not detected in lysates from mitogen-stimulated head kidney leucocytes, despite up-regulation of TNF-Î± mRNAs under the same conditions. During the early onset of AGD in Atlantic salmon, there were no demonstrable differences in the gill tissue expression of TNF-Î±1, TNF-Î±2 nor the interleukin-1 beta (IL-1Î²), inducible nitric oxide synthase (iNOS) and interferon gamma (IFN-Î³) mRNAs compared to tissue from healthy fish. In Atlantic salmon with advanced AGD, IL-1Î² but not TNF-Î±1 or TNF-Î±2 mRNAs was up-regulated and was lesion-restricted. Given that Neoparamoeba spp. modulated both TNF-Î±2 and IL-1Î² in head kidney leucocytes in vitro, it appears that rather than being recalcitrant to Neoparamoeba spp.-mediated TNF-Î± expression, either the parasite can influence the cytokine response during infection, there is ineffective signalling for TNF-Î± expression, or there are too few cells at the site of infection with the capacity to produce TNF-Î±. These data support our previous observation that IL-1Î² mRNA expression is up-regulated in AGD-affected tissue and that TNF-Î± is not intrinsic in AGD-pathogenesis. Â© 2007 Elsevier Ltd. All rights reserved.
Publication titleFish and Shellfish Immunology
Department/SchoolInstitute for Marine and Antarctic Studies
Place of publicationUnited Kingdom