- 3.4.1 PBC 228: Improved diagnostic tests and vaccines for control of bovine tuberculosis.
- 3.4.2 PBC 226: Oral Delivery of bioactives for Possums.
3.4 Vaccine Development
3.4.1 PBC 228: Improved diagnostic tests and vaccines for control of bovine tuberculosis.
| Programme Title: | Improved diagnostic tests and vaccines for control of bovine tuberculosis. |
| Programme Leader: | Dr Bryce Buddle |
| Institution: | AgResearch |
Programme Goal: To improve diagnostic tests and vaccines for control of bovine tuberculosis.
Objective 1
Objective Title: Immunology of bovine tuberculosis.
Research Leader: Dr Bryce Buddle.
Description:
Develop and evaluate diagnostic tests and vaccines for control of bovine tuberculosis in cattle and possums.
- Determine whether vaccination with a DNA vaccine and revaccination with BCG vaccine induces a greater level of protection in cattle against bovine tuberculosis than BCG alone.
- Determine whether age at which calves are vaccinated with BCG is a critical factor in protection against bovine tuberculosis, particularly when they have been sensitised to environmental mycobacteria.
- Determine whether the frequency of IFN_ producing cells as detected by ELISpot correlates with protection against bovine tuberculosis in cattle.
- Cannulate the afferent lymphatic duct of the prescapular lymph node of calves to directly measure the immune responses to BCG vaccination.
- Determine whether a combination of ESAT-6 and CFP10 used in the interferon_ test can be useful in differentiating cattle infected with M. bovis from those infected with environmental mycobacteria.
- Establish whether vaccination of possums with a recombinant BCG expressing a possum cytokine, TNF-__ is more effective in protecting possums against bovine tuberculosis than BCG.
- Compare the efficacy of four different oral bait BCG vaccines prepared by Frank Aldwell (University of Otago) by challenging vaccinated possums with an aerosol of M. bovis.
- Determine the optimal dose of BCG in an encapsulated oral bait vaccine for protection against tuberculosis by vaccinating groups of possums with one of three doses of BCG and later challenging them with M. bovis.
- Submit three papers to refereed journals
Possum Immunology
Description
Develop methods for measuring mucosal immune response in possums and use them to determine how responses are regulated by possum cytokines. Develop vaccine delivery systems suitable for combined delivery of tuberculosis and biocontrol vaccines.
- Produce one new recombinant possum cytokine and determine whether it enhances mucosal immune responses.
- Use immunohistochemistry to locate T cells in Peyer's patches and mesenteric lymph nodes after oral immunisation with BCG.
- Determine the feasibility of using a recombinant BCG vaccine for protecting possums against tuberculosis and inducing an appropriate antibody response to achieve immunosterilisation of possums.
- Submit one paper to a refereed journal.
3.4.2 PBC 226: Oral Delivery of bioactives for Possums.
| Programme Title: | Oral Delivery of bioactives for Possums. |
| Programme Leader: | Dr Bernie McLeod |
| Institution: | AgResearch |
Programme Goal: To develop formulation strategies for oral delivery of biocontrol agents to possums, that maximise stability of the agent and promote its release and uptake in targeted regions of the gut.
Rationale: From research to date, we have identified the luminal and mucosal enzymes that metabolise peptides and proteins in the possum gastrointestinal tract, and determined the relative activity of these enzymes in different regions of the gut. This has demonstrated that the colon and caecum have low levels of both luminal and mucosal enzyme activities, confirming that this region would be the most appropriate to target in oral delivery of peptides and proteins. In addition, we have identified a number of inhibitors that might be used to protect peptides and proteins from enzymatic degradation in the gut. Further, we have studied the permeation of a hydrophilic marker through the intestinal wall in various regions of the intestine and shown that the permeation rate can be enhanced through the judicious use of permeation enhancers. We have investigated the relationship between permeation enhancement and damage to the mucosa, in order to identify useful permeation enhancers and to gauge what concentrations might be used.
The object of the current programme is to develop formulation strategies that are targeted to the hindgut. This will entail protecting the bioactive during its passage through the stomach and small intestine and then promoting its release in the caecum and colon. To achieve this, the bioactive will be presented in a pelleted form, using selected polymer coatings will be designed to disintegrate in the hindgut. The successful development of these formulations will require an understanding of gastrointestinal transit times in possums. We have conducted some preliminary research to investigate gastric residence times in the possum, but more detailed information on gastrointestinal transit is required to design delivery systems that target specific regions of the gut. When this research programme was reviewed, the referee expressed the strong view that further transit studies are required and we wholeheartedly support this opinion.
Irrespective of whether a biocontrol agent has a direct action on a target organ or whether it operates indirectly by invoking an immune response (e.g. immunocontracetion), if it is to be delivered orally we will require information on its stability and metabolism in the gastrointestinal tract and its absorption across the gut wall. Although this programme is primarily aimed the delivery compounds that would act directly on a target organ and therefore the objective is to maximise their absorption into the bloodstream, the strategies involved are largely the same as would be adopted if the immune system (e.g. mucosa or Peyers patches) were to be targeted. A major emphasis of this programme is to develop technologies that can immediately be utilised in the oral delivery of any new biocontrol agent. One aim of this programme is to carry out preliminary screening of metabolism and absorption of some putative biocontrol agents.
Objective 1
Objective Title: Formulation for delivery to hingut.
Research Leader: Prof. I. G. Tucker.
Description:
We have reviewed the literature on current polymer technology to identify products suitable for coating pelleted formulations for delivery t the hindgut. The aim of this objective is to use selected polymers to coat pellets and determine the stability of these polymer-coated pellets in luminal contents of the stomach, duodenum, jejunum and ileum of the possum and their disintegration in lumen contents of the caecum and colon. A second purpose is to screen putative biocontrol agents, using technologies we have developed for evaluating metabolism and absorption in the possum gastrointestinal tract.
Objective 2
Objective Title: Targeting specific regions of gut.
Research Leader: Dr B J McLeod.
Description
To successfully design formulations that will target delivery to a specific region of the possum gut where they will release their payload of biocontrol agent, requires detailed information of gastrointestinal transit in this species. We have collected preliminary data on gastric retention times, but need information on transit through, and residence times in, each region of the gut and on how this is influenced by food intake and the particle size and destiny of the pellets. In this objective, gastrointestinal transit of solutions and of different sized particles through the possum gut, will be determined using radionisotopes.
Contact for Enquiries
Farm Monitoring Programme Manager
Monitoring and Evaluation
MAF Policy
PO Box 2526
Wellington
NEW ZEALAND
Phone: +64 4 894 0623
Fax: +64 4 894 0741
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