# Aspects of the acquired immune response of snapper (Pagrus auratus)

Morrison, RN 2002 , 'Aspects of the acquired immune response of snapper (Pagrus auratus)', PhD thesis, University of Tasmania.

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## Abstract

Snapper (Pagrus auratus) are part of a developing marine aquaculture industry in Australia. However, little is known about the immune system of this species. This study investigated :fundamental aspects of the acquired immune response of snapper. Initially, snapper lg was purified by Staphylococcal protein A (SpA)-agarose affmity chromatography and polyclonal and monoclonal antisera were produced against the purified product then characterised by indirect ELISA, Western blot and flow cytometry. The polyclonal anti-snapper lg antisera bound to both heavy (H) and light (L) chains of reduced snapper serum while three monoclonal anti-snapper lg antibodies bound to the mucosal and/or systemic lg H chain. Both monoclonal and polyclonal anti-snapper lg antisera bound to cells with flow cytometric light scattering profiles similar to lymphocytes as well as macrophages and granulocytes. It is hypothesised that the macrophages and granulocytes do not express mlg but are identified upon binding to systemic lg bound to putative Fe-like receptors (FcR). Monoclonal anti-snapper lg was also shown to mediate quantitative and qualitative changes in PBL intracellular protein tyrosine phosphorylation, indicative of B cell activation. Prominent phosphorylated proteins are hypothesised to be mlg accessory molecules as in murine B cells (CD79α and CD79β.
Other leucocyte differentiation markers were sought and assessed by screening 54 anti-human and anti-murine monoclonal and polyclonal antibodies against snapper PBLs in flow cytometry. An anti-human CD3ε antibody bound to a population ofmlg$$^-$$ PBLs and it is hypothesised that the anti-CDε antibody may have identified T cells, since the peptide immunogen used to produce the antibody is conserved in CD3ε amino acid sequences from humans to sterlet (a Chondrostean).
Preliminary experiments indicated that snapper may utilise cellular communication as in higher vertebrates, although it was not determined if communication was in the form of cognate cellular interaction, soluble factor(s) or a combination of both. Activation with either B cell or T cell mitogens drove both mlg$$^+$$ and mlg$$^-$$ cells into cycle while activation with both mitogens initiated a synergistic proliferative effect, indicative of an interaction between directly or indirectly activated cell types.
Finally, the apparent similarity between teleost B cells and murine B1 cells was assessed using techniques that were originally used to characterise B1 cell derived lg. Snapper lg bound to bromelain treated erythrocytes and binding was inhibited by liposomes of phosphatidylcholine, reminiscent of B1 derived lg. It is hypothesised that the binding to this autoantigen together with the binding of other teleost natural lg to autoantigens are a product of a teleost B1-cell like equivalent.

Item Type: Thesis - PhD Morrison, RN Pagrosomus auratus, Fishes Copyright 2002 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). Chapter 1 appears to be, in part, the equivalent of a pre-print version of an article published as: Morrison, R. N., Nowak, B. F., 2002. The antibody response of teleost fish, Seminars in avian and exotic pet medicine, 11(1), 46-54. The published paper is located in the appendicesChapter 2 appears to be the equivalent of a pre-print version of an article published as: Morrison, R. N., Nowak, B. F., 2001. Affinity purification and partial characterisation of systemic immunoglobulin of the snapper (Pagrus auratus), Aquaculture, 201(1-2), 1-17. The published paper is located in the appendicesChapter 3 appears to be the equivalent of a pre-print version of an article published as: Morrison, R. N., Nowak, B. F., 2000. Elution of snapper, Pagrus auratus (Bloch and Schneider) Ig from a protein A affinity chromatography column yields contamination from the binding ligand, European Association of Fish Pathologists, 20(5), 174-179. The published paper has been released under a Creative Commons Attribution 2.5 UK: Scotland (CC BY 2.5 SCOTLAND) license (https://creativecommons.org/licenses/by/2.5/scotland/) and it is located in the appendicesChapter 4 appears to be the equivalent of a pre-print version of an article published as: Morrison, R. N., Hayball, J. D., Cook, M. T., Nowak, B. F., 2002. Anti-immunoglobulin binding and activation of snapper (Pagrus auratus) leucocytes, Developmental & comparative immunology, 26(3), 247-255. The published paper is located in the appendicesChapter 5 appears to be the equivalent of a post-print version of an article published as: Cook, M. T., Morrison, R. N., Wilkinson, R., Nowak, B. F., Hayball, P. J., Hayball, J. D., 2001. A screen of mammalian antibodies on snapper (Pagrus auratus, Sparidae) peripheral blood leucocytes reveals cross reactivity of an anti-human CD3 antibody with a population of mlg$$^-$$ cells, Developmental & comparative immunology, 25(7), 553-559. The published paper is located in the appendices View statistics for this item