Malaria was identified as one of the first infectious diseases recognised to spread through blood transfusion. Although transfusion acquired malaria is rare, nevertheless it can be lethal if it not diagnosed or treated immediately. It is a continuous challenge for the blood services to identify and exclude asymptomatic malaria infected donors, while minimising the exclusion of uninfected donors. The diagnostic tests in current use present certain limitations which include the use of inherently antigenically variable vaccine candidate proteins that have limited sensitivity against all human malaria species. Additionally, the blood transfusion services also require alternative methods for test and reagents that may be critical to the blood supply. There is therefore a scientific and an operational requirement to use alternative strategies to develop sensitive tests to all the species of malaria. In this study, we have used immunoproteomic approach to define conserved immunogenic malaria proteins. A total of 17 target P. falciparum proteins have been identified using cohorts of malaria immune sera from adults living in endemic areas, as well as by control sera from Europeans, who have never been exposed to malaria. The identified blood stage target antigens were cloned and expressed as recombinant proteins in a suitable bacterial system. In total, 15 target proteins have been expressed with 13 of them have been successfully purified. An ELISA-based system was developed, and the antigenicity of nine target antigens were evaluated using both non-malaria and malaria sera. Single antigen testing gave overall sensitivity of 50 - 84 %, with specificity consistently over 90%. Antigens such as Alpha tubulin and 26s protease showed promising immunogenicity, while Nucleosome assembly protein achieved 100% specificity. Further development of multiple antigens in an ELISA test will be required for continued evaluation of these antigens and the humoral immune response in malaria in general.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:561109 |
| Date | January 2012 |
| Creators | Mohamed Saleh, Rozieyati |
| Contributors | Roberts, David |
| Publisher | University of Oxford |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
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