CD36 selection of 3D7 <it>Plasmodium falciparum </it>associated with severe childhood malaria results in reduced VAR4 expression

• Main Authors: Hviid Lars, Theander Thor G, Staalsoe Trine, Magistrado Pamela A, Jensen Anja TR
• Format: Article
• Language: English
• Published: BMC 2008-10-01
• Series: Malaria Journal
• Online Access: http://www.malariajournal.com/content/7/1/204

<p>Abstract</p> <p>Background</p> <p>A subset of the <it>Plasmodium falciparum </it>erythrocyte membrane protein 1 (PfEMP1_SM) is involved in the cytoadherence of <it>P. falciparum</it>-infected red blood cells (iRBC) contributing to the pathogenesis of severe disease among young children in malaria endemic areas. The PfEMP1_SMare encoded by group A <it>var </it>genes that are composed of a more constrained range of amino acid sequences than groups B and C <it>var </it>genes encoding PfEMP1_UMassociated with uncomplicated malaria. Also, unlike <it>var </it>genes from groups B and C, those from group A do not have sequences consistent with CD36 binding – a major cytoadhesion phenotype of <it>P. falciparum </it>isolates.</p> <p>Methods</p> <p>A 3D7 PfEMP1_SMsub-line (3D7_SM) expressing VAR4 (PFD1235w/MAL8P1.207) was selected for binding to CD36. The protein expression of this parasite line was monitored by surface staining of iRBC using VAR4-specific antibodies. The serological phenotype of the 3D7_SMparasites was determined by flow cytometry using malaria semi-immune and immune plasma and transcription of the 59 <it>var </it>genes in 3D7 were analysed by real-time quantitative reverse transcriptase-polymerase chain reaction (RT-PCR) using <it>var</it>-specific primers.</p> <p>Results</p> <p>A selection-induced increased adhesion of 3D7_SMiRBC to CD36 resulted in a reduced <it>var4 </it>transcription and VAR4 surface expression.</p> <p>Conclusion</p> <p>VAR4 is not involved in CD36 adhesion. The current findings are consistent with the notion that CD36 adhesion is not associated with particular virulent parasite phenotypes, such as those believed to be exhibited by VAR4 expressing parasites.</p>