Specific antibody responses against membrane proteins of erythrocytes infected by Plasmodium falciparum of individuals briefly exposed to malaria

Abstract

BackgroundPlasmodium falciparum infections could lead to severe malaria, principally in non-immune individuals as children and travellers from countries exempted of malaria. Severe malaria is often associated with the sequestration of P. falciparum-infected erythrocytes in deep micro-vascular beds via interactions between host endothelial receptors and parasite ligands expressed on the surface of the infected erythrocyte. Although, serological responses from individuals living in endemic areas against proteins expressed at surface of the infected erythrocyte have been largely studied, seldom data are available about the specific targets of antibody response from travellers.MethodsIn order to characterize antigens recognized by traveller sera, a comparison of IgG immune response against membrane protein extracts from uninfected and P. falciparum-infected red blood cells (iRBC), using immunoblots, was performed between non exposed individuals (n = 31) and briefly exposed individuals (BEI) (n = 38) to malaria transmission.ResultsImmune profile analysis indicated that eight protein bands from iRBC were significantly detected more frequently in the BEI group. Some of these antigenic proteins were identified by an original immuno-proteomic approach.ConclusionCollectively, these data may be useful to characterize the singular serological immune response against a primary malaria infection in individuals briefly exposed to transmission.

Plasmodium falciparum infection-induced changes in erythrocyte membrane proteins

“…The presence of circulating autoantibodies against RBC membrane proteins has already been described in malaria patients Wahlgren et al 1983). Moreover, we recently reported that non-immune healthy adults briefly exposed to malaria endemic areas mounted an antibody response against host proteins from iRBC membrane protein extracts, such as spectrin, adducin or host chaperone proteins (Fontaine et al 2010). These individuals had no history of clinical malaria, and only a minority exhibited clinical signs of a P. falciparum infection during their journeys.…”

“…Both P. falciparum strains were maintained in continuous culture in candle jars (Trager and Jensen 2005;Druilhe and Gentilini 1982). Parasites were cultured as previously described (Fontaine et al 2010). Monthly, six microsatellites were used to control clonality from each P. falciparum strain; their genotypic diversity was confirmed as previously described (Bogreau et al 2006).…”

“…Membrane protein extracts were minimally labelled with 400 pmol of either Cy3, Cy5 or Cy2 CyDye according to the manufacturer's recommended protocols (GE Healthcare, Piscataway, NJ, USA) and as previously described (Pastorino et al 2009;Fontaine et al 2010). Cy3, Cy5 and Cy2 labelled samples were then pooled, and an equal volume of 2× sample buffer was added [8 M urea, 2 M thiourea, 4% (w/v) CHAPS, 10 mM DTT and 1% (v/v) IPG buffer 3-10 (GE Healthcare)].…”

“…Erythrocyte membrane extracts, including the TVN and Maurer cleft for iRBCs, were prepared as described previously (Fontaine et al 2010) and were stored at a final concentration of 2.5 μg/μL in a buffer containing 8 M urea, 2 M thiourea, 4% CHAPS and 30 mM Tris base pH 8.5 (Sigma).…”

“…These protein interactions alter erythrocyte rheologic properties, inducing profound effects on membrane rigidity and, consequently, on iRBC adhesion (Glenister et al 2002). Additionally, we recently reported that travellers that were exposed for a short period of time in malaria-endemic areas could develop autoantibody responses against host proteins expressed in the iRBC membrane protein extracts (Fontaine et al 2010). The emergence of this auto-antibody response restricted to iRBC membrane proteins could be attributed to post-translational modifications of host proteins.…”