Serodiagnosis of Corynebacterium Pseudotuberculosis Infections in Sheep.
Abstract
In a serodiagnostic investigation on CorYnebacterium
pseudotuberculosis infection in sheep, the
phenomenon of synergistic haemolytic activity of
metabolites from £. pseudotuberculosis and C. egui
was investigated. It was found that sheep erythrocytes
were more rapidly haemolysed when first treated
with £. Rseudotuberculosis metabolite than when first
treated with £. egui metabolite. It was concluded
that Q. Rseudotuberculosis metabolite altered the
erythrocytes in such a manner as to make them be
subsequently lysed by C. egui metabolite. Neither
the metabolite of Q. £seudotuberculosis nor that of
£. egui alone haemo Lysed erythrocytes.. The
haemolysis was inhibited by antiserum to either
Q. egui metabolite or to £. pseudotuberculosis
"bacterium.
In ox blood agar the activities of the metabolites
were identical to those of the respective
bacterial cultures, but in addition to partial
haemolysis, Q. l?seudotuberculosis culture had a betahaemolytic
activity. This beta-haemolysis was not
inhibited by 9... I2seudotubercu1osis bacterial
antiserum.
VThen fractionated by gel chromatography f
the active substance of £. egui metabolite eluted
homogeneously but that of Q. J2,seudotuberculosis
- x -
metabolite eluted in a profile suggestive of an
aggregate of different molecules. In agar gel
immunodiffusion, there was cross-reaction
between £. egui metabolite and an antigen of £.
Eseudotuberculosis but there was none between the
metabolites.
Sheep sera were then tested for antibodies
to £. Eseudotuberculosis using bacterial agglutination
test (BAT) and a modified haemolysis inhibition test
(HIT). A C. Eseudotuberculosis strain passaged in
artificial media was found to give an antigen stable
enough for use in BAT. Any sheep serum however,
was found to agglutinate this antigen. Treatment
of serum with Staphylococcal protein A, 2 mercaptoethanol
or adsorption with C. Eseudotuberculosis
cells did not prevent this agglutination. Agglutination
of C. pseudotuberculosis by sheep serum was therefore
concluded to be non-specifico Cross-reaction between
C. Eseudotuberculosis and Co £Iogenes in the
agglutination test was not detected.
BAT titres were found to increase generally
with age of animals and possibly with infection.
There was no relationship between BAT and HIT titres
but HIT positive samples also had high BAT titres.
In either test, there was a high positive correlation
between age and the prevalence of seropositive cases
in the sheep flocks.
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An enzyme-linked immunosorbent assay (ELISA)
for detection of antibodies to Q. ~seudotuberculosis
exotoxin was performed and found slightly more
sensitive than the HIT. Such a test would be a
simple and rapid test for screening sheep for Q.
~seudotuberculosis~infection.
Publisher
University of Nairobi
Rights
Attribution-NonCommercial-NoDerivs 3.0 United StatesUsage Rights
http://creativecommons.org/licenses/by-nc-nd/3.0/us/Collections
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