<it>var </it>gene transcription and PfEMP1 expression in the rosetting and cytoadhesive <it>Plasmodium falciparum </it>clone FCR3S1.2

• Main Authors: Chen Qijun, Normark Johan, Blomqvist Karin, Moll Kirsten, Albrecht Letusa, Wahlgren Mats
• Format: Article
• Language: English
• Published: BMC 2011-01-01
• Series: Malaria Journal
• Online Access: http://www.malariajournal.com/content/10/1/17

<p>Abstract</p> <p>Background</p> <p>The pathogenicity of <it>Plasmodium falciparum </it>is in part due to the ability of the parasitized red blood cell (pRBC) to adhere to intra-vascular host cell receptors and serum-proteins. Binding of the pRBC is mediated by <it>Plasmodium falciparum </it>erythrocyte membrane protein 1 (PfEMP1), a large multi-variant molecule encoded by a family of ≈60 <it>var </it>genes.</p> <p>Methods</p> <p>The study of <it>var </it>gene transcription in the parasite clone FCR3S1.2 was performed by semi-quantitative PCR and quantitative PCR (qPCR). The expression of the major PfEMP1 in FCR3S1.2 pRBC was analysed with polyclonal sera in rosette disruption assays and immunofluorecence.</p> <p>Results</p> <p>Transcripts from <it>var</it>1 (FCR3S1.2_<it>var</it>₁; IT4<it>var</it>21) and other <it>var </it>genes were detected by semi-quantitative PCR but results from qPCR showed that one <it>var </it>gene transcript dominated over the others (FCR3S1.2_<it>var</it>₂; IT4<it>var</it>60). Antibodies raised in rats to the recombinant NTS-DBL1α of <it>var</it>2 produced in <it>E. coli </it>completely and dose-dependently disrupted rosettes (≈95% at a dilution of 1/5). The sera reacted with the Maurer's clefts in trophozoite stages (IFA) and to the infected erythrocyte surface (FACS) indicating that FCR3S1.2_{<it>var2 </it>}encodes the dominant PfEMP1 expressed in this parasite.</p> <p>Conclusion</p> <p>The major transcript in the rosetting model parasite FCR3S1.2 is FCR3S1.2_<it>var</it>₂(IT4<it>var</it>60). The results suggest that this gene encodes the PfEMP1-species responsible for the rosetting phenotype of this parasite. The activity of previously raised antibodies to the NTS-DBL1α of FCR3S1.2_<it>var</it>₁is likely due to cross-reactivity with NTS-DBL1α of the <it>var</it>2 encoded PfEMP1.</p>