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The immunology of bovine brucellosis

Sutherland, Shelley Susan (1980) The immunology of bovine brucellosis. PhD thesis, Murdoch University.

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Abstract

The major objective of this study on bovine brucellosis was to evaluate the newer serological procedures especially the indirect haemolysis test using experimental material from a. controlled field trial with animals of known history.

A preliminary experiment in guinea pigs established that the selected challenge strain 544 caused an increase in the spleen weight and a serological response to the serum agglutination test and complement fixation test. It was concluded that the selected challenge strain was a strain of high virulence for guinea pigs. Testing reagents required for some of the new serological tests were prepared and standardized. They were subsequently tested in a preliminary trial which also permitted the effect of 2 selected challenge dose levels to be examined, staff to familiarize themselves with safety aspects and field and laboratory procedures to be practiced.

In the main trial 13 groups of 10 to 15 animals were used, groups were either left unvaccinated or vaccinated with S19 and/or All groups were mated at 15 months of age and after mating After calving and towards the end of the trial some groups were anamnestically tested and some were intradermally tested. The S45/20. some groups were challenged.

Sera were collected over the 110 week trial period and subsequently used to evaluate the various serological procedures. In addition to the incidence of abortions, stillbirths, weakling calves and healthy calves being observed between 7 and 25 weeks after challenge, specimens were collected for culture at parturition and slaughter.

Several conclusions were drawn from the results and these are summarized below:
1. Vaccination of calves or adult cattle with S19 gave more protection against challenge than vaccination with S45/20 and vaccination of adult cattle with 519 proved superior to vaccination of calves with S19.
2. The indirect haemolysis test reduced the previous problems associated with vaccinal titres to S19.
3. The rough antigen complement fixation test was of no value in the detection of infection in animals previously vaccinated with S45/20.
4. The rapid and persistent serological response to challenge shown by the non-vaccinated but infected animals meant that it was easier to detect infection in these animals than in vaccinated animals which were infected and which often showed aberrant serological reactions after challenge.
5. The indirect haemolysis test showed advantages in that early and persistent titres occurred to this particular test in many of the infected animals.
6. The anamnestic and intradermal tests had no value in previously sensitized animals.

Finally it was concluded that vaccination of cattle with S19 as adults coupled with the use of the indirect haemolysis test would be a very satisfactory combination, not only producing cattle protected from infection but also permitting minimum interference with the serological aspects of an eradication scheme.

Item Type: Thesis (PhD)
Murdoch Affiliation: School of Veterinary Studies
Notes: Note to the author: If you would like to make your thesis openly available on Murdoch University Library's Research Repository, please contact: repository@murdoch.edu.au. Thank you.
Supervisor(s): Penhale, William and Robertson, G.M.
URI: http://researchrepository.murdoch.edu.au/id/eprint/53216
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