Aspects of the cryopreservation of piroplasms have been studied.
The majority of the experimental work was carried out on 2abesia
rodhaini-infected rat blood. The use of three cryoprotectants,
glycerol, dimethylsulphoxide tLI+bl) and polyvißylpyrrolidone (AeVx)), was studied. Greatest success was achieved using lll`d6U at a final
concentration of 10,o. Three cooling rates, slow, rapid and ultrarapid, were studied. These cooling rates were also measured and are
presented in tabular and graphical form. The best results were
achieved using the rapid cooling rate. Two containers, glass ampoules
and pp60 polythene capillary tubing, were studied, the best results
being achieved using pp60.
Two methods for the estimation of the degree of damage suffered
by babesit , rodhaini-infected rat blood during cryopreservation, percentage haemolysis estimation of host red cells and infectivity
measurement, were used. Crystals, thought to be associated with
haemoglobin, were often found in frozen and thawed blood samples.
it was suggested that these crystals affected percentage haemolysis
estimations, rendering this estimation technique invalid, for rat
blood. The infectivity results obtained in the penultimate experiment
in this study cast some doubt also on the validity of the infectivity
titration method used in this study. This is discussed at length in
the discussion section of that experiment.
stage of infection in the host, level of parasitaemia in the
host and nature of diluent used were all shown to have little effect
on the ability of babesia rodhaini- infected rat blood to withstand
the rigours of cryopreservation. In the last experiment in this
study, similar results to those obtained for the cryopreservation
of babesia rodhaìni- infected rat blood were obtained for the oryopreservation of Jabesiamicroti- and Fiuttallia musculi- infected
mouse bloods. From the results obtained for the three piroplasme
studied, and from the evidence in the literature, it is suggested
that the best method tested, involving the rapid cooling of DMSO protected blood in pp60 or in glass ampoules could be applicable
for the cryopreservation of piroplasms in general.