Title:
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Novel approaches for the characterisation of Plasmodium variant surface antigens
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The aim of this research was to identify the erythrocyte surface antigens of P. falciparum infected erythrocytes (IEs) that are expressed following selection of the parasite for adhesion to the placental receptor chondroitin sulphate A (CSA). These surface antigens are considered potential vaccine targets against pregnancy-associated malaria (PAM). Typically P. falciparum surface antigens are highly sensitive to treatment of the IE with the protease trypsin, however variant surface antigen (VSA) mediated adhesion to CSA has often been found to be relatively trypsin resistant. In this study the protease sensitivity of the VSA of CSA binding IEs was determined with regard to serum IgG recognition and placental receptor binding. Discordance between the protease sensitivity for these phenomena was identified; this may have implications for PAM vaccine design. The completion of several Plasmodium genome sequences and advances in mass spectrometry has opened up the field of proteomics to the study of the malaria parasite. Proteomic methods have been applied to the study of Plasmodium VSAs. However, the initial step of these methods, surface antigen labelling, proved problematic. Therefore, this thesis concentrates on the optimisation of these techniques, during which an antibody to the Plasmodium falciparum erythrocyte protein-1 (PfEMP1) family was raised and characterised. This reagent in combination with the advances made for IE surface labelling will be valuable tools for future studies of VSA expression.
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