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Immune response of Barramundi (Lates calcarifer) to Vibrio harveyi bacterin

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Crosbie, Philip(Philip Barry Brice) (2001) Immune response of Barramundi (Lates calcarifer) to Vibrio harveyi bacterin. PhD thesis, University of Tasmania.

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Abstract

Commercial farming of barramundi or Asian seabass (Lates calcanfer) is a burgeoning
industry in Australia and South East Asia. At present there are few serious bacterial
infections, however disease caused by Vibrio harveyi infection is an on-going problem with
the potential to become chronic as the industry expands. Therefore, the development of an
effective vaccine against vibriosis was seen as a prudent strategy for the future success of
barramundi production. This thesis reports on the development of appropriate reagents for in
vitro monitoring of immune responses to a bacterin, and subsequent validation in laboratory
trials where fish were immunised with a bacterin via various routes or, with
lipopolysaccharide (LPS) via intraperitoneal (IP) injection.
Barramundi immunoglobulin was isolated by affinity chromatography using either mannanbinding
protein (MBP) or Staphylococcal protein A (SpA) as capture ligands. Both isolation
products were used to produce polyclonal antisera in rabbits, which were subsequently
compared for specificity and titer. Two antisera were used to monitor anti-V. harveyi
antibody activity in barramundi serum after primary and secondary immunisations with
bacterin via the IP route. Elevated antibody levels after secondary immunisation indicated a
memory response. The routes of bacterin administration were investigated in terms of antibody production and
some non-specific immune parameters. It was found that barramundi respond systemically
to bacterin delivered by IP injection, immersion (IMIM) and anal intubation (Al). The
highest and most consistent response was in fish treated via IP followed by AT then IMM.
This consistency of response from IP-treated fish carried over to bacterial inhibitory activity
of serum where all demonstrated >50% inhibitory activity relative to non-immune controls.
There was no significant enhancement of serum lysozyme activity nor head kidney
macrophage phagocytic activity as a result of any immunisation procedure.
Finally, the response of barramundi to IP immunisation with bacterin or lipopolysaccharide
(LPS) extracted from the bacterium was compared to elucidate the role of the latter. There were systemic antibody responses to both preparations with little difference noted in the
magnitude of the response. However, bacterial inhibitory activity of serum was highest in
the bacterin treament group. This may indicate that anti-LPS antibodies do not agglutinate to
the same extent as anti-whole bacterial cell antibodies.
In conclusion, systemic antibody and bacterial inhibitory activity after immunisations with
the bacterin suggests that it may be an effective vaccine and oral administration is worth
investigation. The protective role of LPS is unclear, though relatively lower bacterial
inhibitory activity of anti-LPS antibodies suggests it may be less protective than anti-whole
bacterial cell antibodies.

Item Type: Thesis (PhD)
Keywords: Giant perch, Giant perch
Copyright Holders: The Author
Copyright Information:

Copyright 2001 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, 2001. Includes bibliographical references

Date Deposited: 09 Dec 2014 00:06
Last Modified: 11 Mar 2016 05:54
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