dc.contributor.author | Loiselet, Rachel Joëlle Lysiane | en |
dc.date.accessioned | 2018-05-14T10:14:07Z | |
dc.date.available | 2018-05-14T10:14:07Z | |
dc.date.issued | 2003 | |
dc.identifier.uri | http://hdl.handle.net/1842/29853 | |
dc.description.abstract | | en |
dc.description.abstract | Mycoplasma mycoides subsp. mycoides small colony type {MmmSC) is the
causative agent of contagious bovine pleuropneumonia (CBPP), a major disease of
cattle in Africa for which current vaccines exhibit a poor efficacy. MmmSC possesses
a capsular polysaccharide (CPS) believed to be an important virulence factor.
Antibodies directed against CPS are bactericidal in an in vitro growth inhibition test
(GIT). Therefore, CPS is a good vaccine candidate. | en |
dc.description.abstract | The aim of this thesis was to investigate the vaccine potential of MmmSC
CPS. | en |
dc.description.abstract | Before using CPS as a vaccine, the immunogenic structure of CPS needed to
be studied. MmmSC strains were tested with rabbit antisera (raised against different
MmmSC strains) in a GIT. The results showed that CPS was conserved between the
strains. Purified CPS from different MmmSC strains were then investigated with
monoclonal antibodies (mAbs) in an enzyme linked immunosorbent assay (ELISA).
It appeared that CPS from all the strains were recognised by the mAbs, except the
strain PG1 that had a low signal with two of the mAbs. GIT was used with mAbs that
recognised MmmSC CPS to test their growth inhibiting (GI) activity; all of the mAbs
used in the GIT were bactericidal. | en |
dc.description.abstract | The specificity of these mAbs was then investigated, using an ELISA, against
other mycoplasmas, Mycoplasma mycoides subsp. mycoides large colony and
Mycoplasma mycoides subsp. capri. The results obtained suggested that the mAbs
recognised at least three different epitopes on CPS. | en |
dc.description.abstract | A competitive ELISA was performed to clarify the number of epitopes that
these mAbs recognised. No conclusion could be drawn from this experiment since
the results were unclear. | en |
dc.description.abstract | Since antibodies to CPS are bactericidal in vitro, this suggested they were
protective against MmmSC. Passive immunisation of mice with a bactericidal mAb
directed against CPS was used to investigate the protective efficacy of anti-CPS
antibodies in vivo. After injection with the antibody, mice were challenged with an
MmmSC strain. The incidence and the duration of mycoplasmaemia were used to
assess the protection given by this antibody. No significant difference could be seen
between mice passively immunised with anti-CPS antibody and the control group,
suggesting that a bactericidal antibody was not protective in vivo in mice against
challenge with MmmSC. | en |
dc.description.abstract | The type of immune response to CPS was examined in three groups of cattle:
M/nmSC-intubated animals, CBPP-vaccinated and unvaccinated animals in contact
with MwrzSC-intubated cattle. The results showed that only a quarter of CBPPvaccinated cattle had an immune response against CPS. The immune response
against CPS in the three different groups was of IgM type even after a second
exposure to the pathogen where it could have been expected an IgG type immune
response. | en |
dc.description.abstract | The lack of immune response to CPS in cattle might be due to cross-reactions
with bovine lung. Cross-reactions between bovine lung and MmmSC CPS were
confirmed by western-blot with anti-MwwSC or anti-CPS sera from rabbits, mice
and mAbs. It was not possible to know whether antibodies recognising both CPS and
bovine lung were present in anti-AfrwwSC cow sera because of a background signal
due to the secondary antibody specific for cow immunoglobulins. | en |
dc.description.abstract | To minimise the cost of CPS vaccine production, polysaccharides from other
sources could be used as a vaccine. A western-blot was then performed to examine
the cross-reactions between MmmSC CPS and carbohydrates from cereals with
A/mmSC-infected cow sera, MmmSC-immunised rabbit sera and mAbs. The results
showed that CPS shared epitopes with the polysaccharides from the cereals used in
this experiment. | en |
dc.publisher | The University of Edinburgh | en |
dc.relation.ispartof | Annexe Thesis Digitisation Project 2018 Block 18 | en |
dc.relation.isreferencedby | Already catalogued | en |
dc.title | Immune response to and pathogenic mechanisms of contagious bovine pleuropneumonia infection: investigation of the importance of the capsular polysaccharide and assessment of its vaccine potential | en |
dc.type | Thesis or Dissertation | en |
dc.type.qualificationlevel | Doctoral | en |
dc.type.qualificationname | PhD Doctor of Philosophy | en |