Department of Microbiology, Tumor and Cell Biology (MTC), Karolinska Institutet, Box 280, SE-171 77 Stockholm, Sweden.
Malar J. 2011 Jan 25;10:17. doi: 10.1186/1475-2875-10-17.
The pathogenicity of Plasmodium falciparum 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 Plasmodium falciparum erythrocyte membrane protein 1 (PfEMP1), a large multi-variant molecule encoded by a family of ≈60 var genes.
The study of var 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 immunofluorescence.
Transcripts from var1 (FCR3S1.2(var1); IT4var21) and other var genes were detected by semi-quantitative PCR but results from qPCR showed that one var gene transcript dominated over the others (FCR3S1.2(var2); IT4var60). Antibodies raised in rats to the recombinant NTS-DBL1α of var2 produced in E. coli 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(var2) encodes the dominant PfEMP1 expressed in this parasite.
The major transcript in the rosetting model parasite FCR3S1.2 is FCR3S1.2(var2) (IT4var60). 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(var1) is likely due to cross-reactivity with NTS-DBL1α of the var2 encoded PfEMP1.
疟原虫的致病性部分归因于寄生的红细胞（pRBC）与血管内宿主细胞受体和血清蛋白的粘附能力。pRBC 的结合由疟原虫红细胞膜蛋白 1（PfEMP1）介导，PfEMP1 是一种由约 60 个 var 基因家族编码的大型多变异分子。
通过半定量 PCR 和定量 PCR（qPCR）研究寄生虫克隆 FCR3S1.2 中的 var 基因转录。在 FCR3S1.2 pRBC 中用多克隆血清进行玫瑰花结破坏试验和免疫荧光分析，分析主要 PfEMP1 的表达。
通过半定量 PCR 检测到 var1（FCR3S1.2（var1）；IT4var21）和其他 var 基因的转录本，但 qPCR 的结果表明，一个 var 基因转录本占主导地位（FCR3S1.2（var2）；IT4var60）。用大肠杆菌中产生的 var2 的重组 NTS-DBL1α 免疫大鼠产生的抗体完全且剂量依赖性地破坏玫瑰花结（稀释度为 1/5 时约为 95%）。血清与滋养体阶段的 Maurer 裂孔（IFA）和感染的红细胞表面（FACS）反应，表明 FCR3S1.2（var2）编码在该寄生虫中表达的主要 PfEMP1。
在玫瑰花结模型寄生虫 FCR3S1.2 中主要的转录本是 FCR3S1.2（var2）（IT4var60）。结果表明，该基因编码与该寄生虫玫瑰花结表型相关的 PfEMP1 物种。先前针对 FCR3S1.2（var1）的 NTS-DBL1α 产生的抗体的活性可能是由于与 var2 编码的 PfEMP1 的 NTS-DBL1α 发生交叉反应。
