Skip to main content

DEVELOPMENT OF A DELIVERY SYSTEM FOR THE ORAL ADMINISTRATION OF VACCINES FOR THE PREVENTION OF DISEASES IN FISH IN AQUACULTURE

Objective

The rapid expansion in salmon aquaculture has brought with it a proliferation of pathogens. To date the industry has mainly tackled this problem by recourse to ever increasing amounts of antibiotics, and the increased use of immersion bath vaccination. The latter technique can only be used when the fish are small and vaccine boosting during the sea water phase is not possible. Oral vaccination is very attractive since it is suitable for mass administration to fish of all sizes and in any culture system with no stress on the fish, and boosting is possible when required. Previous attempts at oral vaccination appear to have failed due to the destruction of the antigens in the stomach of the fish. The ideal delivery system must have the potential capability of firstly protecting the antigens and secondly, delivering the antigen to the required site by a number of mechanisms.

The major objective of the project is the development of a new delivery vehicle for the oral administration of vaccines to fish for the prevention of disease.
Vaccination is accepted to be one of the essential tools for preventing, controlling, and generally reducing the impact of disease in farmed animals. Over the past decade the credibility of vaccines have also become established in the aquaculture industry. The major objective of this project is to develop orally administered vaccines. This method of vaccination will overcome the many practical problems which currently restrict the use of vaccines in farmed fish.
We have investigated the nature of existing bacterial antigens to establish their suitability for liposome encapsulation. Physical constraints suggested that alteration to the antigen form would be required to allow successful encapsulation using biocompatible liposome technology. These modifications were carried out. The resulting antigens were shown to be both immunogenic and protective although less so than existing antigens. New approaches were investigated for the production of antigens from Aeromonas salmonicida and Yersinia ruckeri. Evaluation of these new methods has been initiated for Aeromonas salmonicida and are on going for other antigens.

Vaccination is accepted to be one of the essential tools for preventing, controlling, and generally reducing the impact of disease in farmed animals. Over the past decade the credibility of vaccines have also become established in the aquaculture industry. The major objective of this project is to develop orally administered vaccines. This method of vaccination will overcome the many practical problems which currently restrict the use of vaccines in farmed fish.
UCG have carried out work to evaluate the acceptability of various liposome and matrix formulations provided and problems of palatability have been encountered. The pH variation and osmolarity of the gastrointestinal tract of salmonid species have been evaluated under various feeding conditions. Fluorescent compounds have been used as antigen analogues to determine the fate of liposome protected antigen. This study indicates that the fate of antigen should be monitored directly using immunocytochemical techniques.
The research tasks are the following:
determination of the antigen forms of three fish pathogens, Yersinia ruckeri, Vibrio anguillarum and Aeromonas salmonicida, which will produce maximum immunostimulation in salmon;
determination of the site of uptake that will produce maximum oral immunostimulation;
development of a delivery system which will protect and target the antigen to the active site, and which will promote uptake.

Different forms of antigenic material suitable for encapsulation will be produced and tested for immunostimulation in salmon. Model encapsulation vehicles will be constructed. Marker gut release studies using these vehicles will determine their stability in the gut and site of uptake of the delivery vehicle or its contents. Labelled optimized antigenic material will be encapsulated and the site of uptake and the immune response determined. If a good immune response is obtained fish farm trials of the oral encapsulated vaccines will commence.

Funding Scheme

CSC - Cost-sharing contracts

Coordinator

Biocompatibles Ltd
Address
Brunel Science Park Kingston Lane
UB8 3PQ Uxbridge
United Kingdom

Participants (2)

ARGE VEGETATIONSOEKOLOGIE UND LANDSCHAFTSPLANUNG - KORNER, MAIR, WRBKA OEG
Austria
Address
Theobaldgasse 16/4
1060 Wien
NATIONAL UNIVERSITY OF IRELAND, GALWAY
Ireland
Address
University Road
90 Galway