Research Interests of Professor Theresa Coetzer

We study poultry pathogens and trypanosomes of importance in South Africa and the rest of Africa to develop diagnostic assays, therapeutic strategies and ultimately vaccines against the diseases caused by these infectious agents. Viral diseases of importance in the South African poultry industry include infectious bursal disease (IBD; Gumboro disease) and Newcastle disease, bacterial diseases include infectious coryza, caused by the bacterium Haemophilus paragallinarum and its novel South African NAD independent variant and salmonellosis, mainly caused by Salmonella enteritidis. These diseases result in reduced growth of broilers and cause impaired egg production in layers and breeders. Salmonellosis does not only cause substantial losses in the poultry industry through mortality and reduced production, but also cause infection in humans through ingestion of eggs. It is, therefore, of critical importance to ascertain the molecular basis for disease development in vaccinated flocks and to develop sensitive diagnostic assays and effective vaccines against these diseases. We focus on the molecules involved in the binding of the pathogens to their host tissues, antigenic differences between different strains of pathogens and between those of field strains and vaccine strains. We use techniques in protein purification and characterisation, immunochemistry and molecular biology.
African trypanosomes infect almost all domestic animals, many wild animals and man. Cattle trypanosomiasis (nagana, from the Zulu word for “poorly”) is of great economic importance in many parts of Africa, including the KwaZulu-Natal region of South Africa. Some of the most potentially productive agricultural land in Africa (a quarter of the continent) is under-utilised because of the threat of nagana.
Trypanosomiasis is currently prevented using environmentally unsafe insecticides to control tsetse fly vector populations. Alternatively entire populations of wild animal species serving as trypanosome reservoirs were eliminated in Zululand in the 1920’s.
Our approach is to identify means of controlling trypanosomiasis by interfering with the activity of enzymes that are essential for parasite viability. We study the effect of chalcone, acyl hydrazide, vinyl sulfone, suramin and peptidyl -aminoalkyl phosphonate diphenyl ester derivatives on the activity of the trypanosomal proteases, i.e. trypanopain-Tb, a serine oligopeptidase and a multicatalytic protease and their ability to kill trypanosomes in culture. The trypanocidal effect of a number of traditional medicinal plants on these proteases as well as the trypanosomal proteasome are also being evaluated in a collaboration between traditional healers and scientists. A number of these approaches are showing potential as therapeutic agents.