The dissertation is divided into five parts, namely studies
on the parasite-host models in vivo, in vitro culture of Taenia
taeniaeformis oncospheres, in vitro growth and maintenance of mature
larvae of Taenia saginata and T. taeniaeformis, the antigens released
by the latter in vitro and finally the immunogenic properties of
these antigens.
In Part I, four strains of T. taeniaeformis, from Belgium (B),
Iraq (i), Malaysia (m) and Scotland (S), were compared as regards
their infectivity for CF1 mice and Sprague-Dawley rats. Two strains,
S and M, appeared to be almost exclusively adapted to mice and rats
respectively. Mice were generally more susceptible than rats for
strains B and I. Thin layer starch gel electrophoresis of extracts
of T. taeniaeformis of these four strains showed different patterns
for the isoenzymes of hexokinase.
Part II is concerned with in vitro culture of T. taeniaeformis
starting with oncospheres. Techniques for hatching and activating
oncospheres based on peptic digestion followed by incubation in an
artificial intestinal solution, gave unsatisfactory results. Better
results were obtained by first disintegrating the embryophores with
sodium hypochlorite, followed by stationary incubation in a culture
medium containing trypsin, bile and serum. Attempts to cultivate
these oncospheres in vitro were not as successful as those described
by Heath (1973).
Part III describes attempts to monitor the maintenance of
T. taeniaeformis strobilocerci in vitro. The weight of the larvae,
glucose uptake and lactic acid production were measured at regular
intervals. None of these parameters proved to be suitable for
comparing different media; the response was either too slow or too
irregular to be reliable. Different types of culture for T. saginata
metacestodes were tried. The best growth was obtained by using a
diphasic medium with disrupted coagulated serum as the solid sub¬
strate. The most developed forms showed segmentation and early
development of the sexual organs.
Studies concerned with the nature of the metabolic antigens are
described in Part IV. These were primarily concerned with establish¬
ing whether these antigens were materially different from somatic
antigen or were merely the result of progressive disintegration of
the worms in vitro. Immunoelectrophoresis, ELISA for detecting
antibodies and ITAS-ELISA for detecting antigen each allowed the
metabolic and somatic antigens to be distinguished. The former
appeared to be similar to cyst fluid, in so far as precipitating
antigens were concerned, whereas in the ELISA and ITAS-ELISA studies
metabolic antigen seemed to give more specific results. Cyst fluid
or somatic antigen gave less specificity with sera from mice infected
with T. taeniaeformis or Taenia crassiceps. Furthermore, as the
level of somatic antigen increased in culture fluids, so did the
specificity decrease.
This release of antigens into culture media was studied in
relation to time for different culture media and also by comparing
this for dead and living larvae maintained under the same in vitro
conditions. The results suggested that the release rate for antigen
as measured by ITAS-ELISA could provide a useful means of monitoring
viii.
such cultures, since the inverse relationship between this and the
integrity of the cultured metacestodes was more consistent than any
of the parameters studied in Part III or the release rate for
metabolic antigen.
Finally, a study of the efficacy of these metabolites as
immunogens was undertaken in mice and rats and is described in
Part V. The results of these experiments were inconsistent; some
batches of culture antigen gave significant protection but no
relationship between this and their protein content or the proportion
of metabolic and somatic antigen could be demonstrated.
