My main aim was to investigate human Ab responses to RAP1. For this study, I have developed nine recombinant RAP1 proteins (rRAP1) representing almost the entire sequence of mature RAP1 that have been expressed in <I>Escherichia coli</I> as soluble hexa-histidine or GST fusions. The antigenicity of the rRAP1 proteins was assessed by immunogenicity tests in mice and rabbits, and by <I>P. falciparum </I>RAP1-specific mAbs recognising a defined linear epitope. Antisera to seven of the rRAP1 proteins specifically reacted with parasites in immunofluorescence as well as parasite-derived RAP1 protein (<I>Pf</I>RAP1) in immunoblotting. These results indicate that these rRAP1 proteins bear antigenic similarity to <I>P. falciparum</I> RAP1. Affinity purified Abs produced in rabbits against three rRAP1 proteins block invasion of red blood cells by merozoites, and this suggests that the proteins contain protective epitopes. Analysis of serum Abs of residents of malaria endemic regions by ELISA shows that RAP1 is antigenic during naturally transmitted malaria infection. The recombinant proteins are specifically recognised by IgG Abs, with detectable Abs directed mostly towards fragments containing N-terminal sequences of mature <I>Pf</I>RAP1. By contrast, only few individuals had Abs to the C-terminus. Abs from malaria patients do not complete for a linear epitope recognised by an inhibitory anti-RAP1 mAb. This indicates that Abs from malaria patients bind mostly to epitopes different from that recognised by the inhibitory mAb. In a longitudinal study of individuals conducted over a period of 4 years in a region of seasonal and unstable malaria transmission, I have found that Abs to RAP1 are produced only after a documented clinical malaria.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:650998 |
| Date | January 1998 |
| Creators | Fonjungo, Peter Nkong |
| Publisher | University of Edinburgh |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://hdl.handle.net/1842/12022 |
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