Which Th pathway is involved during late stage amoebic gill disease?

Ottavia Benedicenti, Catherine Collins, Tiehui Wang, Una McCarthy, Christopher J Secombes

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37 Citations (Scopus)
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Amoebic gill disease (AGD) is an emerging disease in North European Atlantic salmon (Salmo salar Linnaeus 1758) aquaculture caused by the amoeba Paramoeba perurans. The host immune response to AGD infection is still not well understood despite past attempts to investigate hostpathogen interactions. With the significant increase in our knowledge of cytokine genes potentially involved in Th responses in recent years, we examined their involvement in this disease using Atlantic salmon post-smolts sampled 3 weeks after exposure to either 500 or 5000 cells/l P. perurans. Gene expression analysis of cytokines potentially involved in the different Th pathways was performed on the first gill arch including the interbranchial lymphoid tissue (ILT). Th1, Th17 and Treg pathways were found to be significantly down regulated, mainly in samples from fish given the higher dose. In contrast, the Th2 pathway was found to be significantly up regulated by both infection doses. Correlation analysis of the gene expression data and the P. perurans load, assessed by real time RTPCR of the 18S rRNA, was also performed. In humans, Th2 driven responses are characterized by the production of IgE, which in the majority of worm infections results in the generation of a Th2-mediated response and directs the immune system away from a Th1 inflammatory response. The present results seen during late stage AGD suggest that either an immune evasion strategy, similar to the responses driven by helminthic parasites to avoid cell-mediated killing mechanisms, or an allergic reaction caused by the parasite is occurring.
Original languageEnglish
Pages (from-to)417-425
Number of pages9
JournalFish & Shellfish Immunology
Issue number2
Early online date9 Jul 2015
Publication statusPublished - Oct 2015

Bibliographical note

This work was supported financially by the Marine Collaboration Research Forum (MarCRF) which is a collaboration be-tween the University of Aberdeen and Marine Scotland Science,Marine Laboratory (MSS). Thanks go to Dr. David Bruno (MSS) and Patricia Noguera (MSS) for the assessment of the gill core/AGD pathology; Dr. Malcolm Hall (MSS) for statistical consultancy; Louise Feehan (MSS), Ben Williamson (MSS) and Mark Paterson (MSS) for the management of the aquarium and the fish care;Mark Fordyce (MSS) for the H&E stain and scan of the slides; Dr.Ayham Alnabulsi for providing the anti-Ig antibodies; the histology facility at the Institute of Medical Sciences, University of Aberdeen; Carola Dehler for providing the Atlantic salmon(muscle) DNA samples used for checking whether amplification of gDNA occurred during real time RT-PCR


  • amoebic gill disease
  • Atlantic salmon
  • Th pathways
  • cytokines
  • interbranchial lymphoid tissue


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