A Thesis submitted to the Faculty of Science, University of the Witwatersrand, Johannesburg for the Degree of Doctor of Philosophy / This thesis describes the characterisation of southern African isolates of Plasmodium falciparum according to isoenzyme type, antigen variants and drug sensitivity. Nineteen southern African isolates and a Gambian reference isolate were cultured in vitro in gassed tissue culture flasks. Polyacrylamide gel electrophoresis with use of 5 enzymes revealed little variation amongst the isolates and the frequencies of enzyme forms were similar to those of isolates from other parts of the world. Antigenic diversity was demonstrated using a panel of 9 monoclonal antibodies in the indirect fluorescent antibody test. The antigenic composition of 70% of isolates was markedly different to any obtained in other geographical areas. Both characterisation techniques revealed a mixture of parasite types in some isolates. However I the characteristics of most of these heterogeneous isolates were not stable with time in culture. Most isolates proved to be resistant to chloroquine in a 48-hour growth inhibition test. A wide range in Pyrimethamine susceptibilities was detected although most isolates exhibited a low level of resistance to this drug. In the radioisotope uptake assay, the halofantrine IC50 values obtained were comparable with those of West African isolates but were higher than the TC50s of south-East Asian isolates. All of the isolates resistant to chloroquine in the 48-hour test were resistant in the radioisotope assay. However, 1 isolate shown to be sensitive to chloroquine in the first test was found to be resistant in the 3Hhypoxanthine incorporation method. This was assumed to be the result of selection of resistant clones. Southern African isolates were shown to be fully susceptible to mefloquine, but had reduced susceptibility to quinine and sulphadoxine/ pyrimethaInine. Most isolates were sensitive to amodiaquine. A field study of 31 KwaZulu isolates of P. falciparum obtained in 1987 and 1988 showed 29 to be resistant to chloroquine in the 24-hour microtechnique, with the majority being highly resistant. Chloroquine resistance was confirmed in this area in a field study carried out in 1989 but in 1990 all 4 isolates tested were sensitive to the drug. In 1989, 12 out of 13 KwaZulu isolates were resistant to amodiaquine and most isolates showed reduced susceptibility to quinine and sulphadoxine/ pyrimethamine. / Andrew Chakane 2018
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:wits/oai:wiredspace.wits.ac.za:10539/24748 |
| Date | January 1993 |
| Creators | Freese, Janet Anne |
| Source Sets | South African National ETD Portal |
| Language | English |
| Detected Language | English |
| Type | Thesis |
| Format | application/pdf, application/pdf |
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