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Immune-regulatory genes in amoebic gill disease : potential for immunomodulation

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Bridle, Andrew Roderick (2005) Immune-regulatory genes in amoebic gill disease : potential for immunomodulation. PhD thesis, University of Tasmania.

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Abstract

Amoebic Gill Disease (AGD) is the most significant health problem affecting
Atlantic salmon, Salmo salar, culture in Tasmania, Australia. Caused by the
ectoparasite Neoparamoeba sp., AGD is an emerging disease in several other
countries (USA, Ireland, France, Spain, Chile, New Zealand) and affects several
other cultured fish species (rainbow trout, Oncorhynchus mykiss, coho salmon,
Oncorhynchus kisutch, turbot, Scophthalmus maximus). AGD and the cost of
treatment, freshwater bathing, have negatively impacted on the production of
Atlantic salmon in Tasmania. Consequently, alternative AGD management
strategies are required. Thus an understanding of the disease processes associated
with AOD pathology and the immune response to AGD is essential to the
development of alternative AGD management strategies. Therefore, the immune
response to AGD was partially characterised using molecular techniques, and the
potential use of immunostimulants to reduce the impact of AGD on the Tasmanian
salmonid industry was assessed. The transcriptional profile of selected immune-regulatory genes in the gill, liver
and anterior kidney of experimentally infected Atlantic salmon and rainbow trout
was assessed using semi-quantitative RT-PCR and quantitative real-time RT-PCR.
Atlantic salmon interleukin-10 (IL-1)3) was shown to be up-regulated in the gills at
14 d post-inoculation (p.i.). In rainbow trout the expression of IL-1(3 and inducible
nitric oxide synthase (iNOS) mRNA was significantly up-regulated in the gills at
both 7 and 14 d p.i., while interleukin-8 was significantly up-regulated in the liverof AGD-affected trout at 7 d p.i. mRNA transcripts were localised by in situ
hybridisation to pavement epithelial cells lining the primary and secondary
lamellae of AGD-affected and control Atlantic salmon gills. These data
demonstrated the involvement of the immune response to AGD at the molecular
level and indicated the significance of the response at the site of infection.
Intraperitoneal administration of immunostimulatory CpG oligodeoxynucleotides
increased the resistance of Atlantic salmon to AGD. However, oral administration
of 0-glucans, a well-known and potentially more cost-effective immunostimulant,
was unable to enhance resistance to AGD. Nonetheless, a group of Atlantic salmon
were able to survive an experimental AGD challenge. These findings allowed a
preliminary AGD infection model to be proposed, and further our knowledge of the
fish immune response to parasitic infection. The implications of this research show
the potential for an effective immunological-based AGD management strategy such
as use of a vaccine, immunostimulants or a selective breeding program.

Item Type: Thesis (PhD)
Keywords: Salmon, Salmon, Salmon farming
Copyright Holders: The Author
Copyright Information:

Copyright 2005 the Author - The University is continuing to endeavour to trace the copyright
owner(s) and in the meantime this item has been reproduced here in good faith. We
would be pleased to hear from the copyright owner(s).

Additional Information:

Thesis (Ph.D.)--University of Tasmania, 2005. Includes bibliographical references

Date Deposited: 25 Nov 2014 00:54
Last Modified: 21 Jun 2016 01:31
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