Field and laboratory studies of bovine genital campylobacteriosis with particular reference to diagnosis

Agumbah, Gilbert Julian Okwaro (1981) Field and laboratory studies of bovine genital campylobacteriosis with particular reference to diagnosis. PhD thesis, University of Glasgow.

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Crude sonicated antigens of Campylobacter fetus have been shown to possess several precipitating antigens of which at least two and at most four, possibly five, were anodally migrating. These antigens reacted with rabbit anti-C. fetus whole cell antisera in the counter-immunoelectrophoresis (CIE) system to produce immunoprecipitates in agarose gels. The reaction appeared to be pH dependent as at pH 8.61 it was less pronounced than at pH 6.6-7.6, although it was not possible to classify the antigens using the CIE test. These antigens failed to react with phenol saline extracts of vaginal mucus from cows known to be infected with C. fetus and which reacted to the vaginal mucus agglutination test (VMAT). Further studies revealed that the agarose type used as support medium was of importance in the use of CIE for immunodiagnosis of C. fetus infection in cattle. Two agarose types, Agarose B (Pharmacia, Sweden) and Litex HSB Agarose (Litex, Denmark) were found suitable and three others unsuit-able. The vaginal mucus required to be diluted 1:4 with normal saline, homogenized and centrifuged. The development of directly visible precipitation was favoured by concentrating the sol to 0.5-1.0 ml by dialysis against polyethylene glycol (Carbowax, Sigma Chemicals, U.S.A.) before testing. Despite concentration, the staining of immunoplates increased the chances of detecting positive cases. That the effect of pH was important was further emphasised when bovine mucus samples were found to be most reactive at pH 7.6 and 7.9. Buffer types tested did not affect the test as long as the gel pH was 7.6 and 7.9. However, the involve-went of more than one biotype of C. fetus in field infections led to the realisation that a mixed sonicated antigen comprising one strain of C. fetus subsp fetus and one strain of C. fetus subsp venerealis provided a wide antigenic spectrum that detected all field infections investigated by the CIE test. In order to determine the specificity of the test, virgin heifers shown to be free of infection and to be immunologically negative, were infected with C. fetus subsp fetus to study immunoconversion and the type of immunoglobulins reactive in the CIE test. All heifers continued to be immunologically negative until about 3-4 weeks after infection when evidence of immunoconversion was shown by the VMAT. On the 37th day post infection (Dpi), immunoconversion was also detected by CIE in two of the three heifers and in the third heifer on day 113 post infection. From then onwards both VMAT and CIE detected the presence of antibodies, with the period 141-193 days post infection showing the clearest CIE reactions as samples tested over this period from all heifers were positive. While the VMAT tended to be unreliable after about 5 months post infection, positive CIE reactions were recorded over a longer period. In the one heifer which was pregnant even though still harbouring the infection, an anamnestic response to the presence of C. fetus organisms in the cervico-vaginal area was thought to have occurred because positive CIE reaction reappeared 36 days after parturition and persisted till the end of the experimental period at 383 days post infection. On the basis of studies of the antibodies in the vaginal mucus of the three experimentally infected heifers and field samples, IgG1 was found to be the predominant antibody associated with CIE reactions. IgA also participated in this reaction but IgM activity was demonstrated in only one sample. IgG2 apparently did not participate to any level measurable by the absorption method used. Because it was - possible that the more abundant antibodies could mask the presence of those present in smaller quantities, it was not possible to draw conclusions regarding the activity of the minor antibodies. (Abstract shortened by ProQuest.).

Item Type: Thesis (PhD)
Qualification Level: Doctoral
Additional Information: Adviser: H Boyd
Keywords: Animal diseases
Date of Award: 1981
Depositing User: Enlighten Team
Unique ID: glathesis:1981-73207
Copyright: Copyright of this thesis is held by the author.
Date Deposited: 14 Jun 2019 08:56
Last Modified: 14 Jun 2019 08:56

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