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      The var3 genes of Plasmodium falciparum 3D7 strain are differentially expressed in infected erythrocytes Translated title: Les gènes var3 de la souche 3D7 de Plasmodium falciparum sont exprimés de manière différentielle dans les érythrocytes infectés

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          Plasmodium falciparum erythrocyte membrane protein 1 (PfEMP1) is an important virulence factor encoded by a family of 59 var genes, including 56 var genes plus 3 small var3 genes. The var genes are among the most diverse sequences in the P. falciparum genome, but the var3 genes are found conserved in most P. falciparum strains. Previous studies have been mainly focused on the typical var genes, while the biological characteristics of the var3 genes remain unknown. In this study, the three var3 genes, PF3D7_0100300, PF3D7_0600400, and PF3D7_0937600, were found to be transcribed in the erythrocytic stages of P. falciparum, with a peak in the transcription level at 16 h post-invasion, but terminated immediately after 16 h post-invasion. The encoded protein of PF3D7_0600400 could be detected in both the late trophozoite stage and schizont stage, while the encoded proteins of PF3D7_0100300 and PF3D7_0937600 could only be detected in the late trophozoite stage and schizont stage, respectively. Thus, the var3 genes of the P. falciparum 3D7 strain were differentially expressed during the erythrocytic development of the parasite.

          Translated abstract

          La protéine 1 de membrane de l’érythrocyte de Plasmodium falciparum (PfEMP1) est un important facteur de virulence, codé par une famille de 59 gènes var, qui comprend cinquante-six gènes var et trois petits gènes var3. Les gènes var sont parmi les séquences les plus diverses dans le génome de P. falciparum, mais sont sont conservés dans la plupart des souches de P. falciparum. Des études antérieures ont été principalement axées sur les gènes var typiques, tandis que les caractéristiques biologiques des gènes var3 restent inconnues. Dans cette étude, il a été trouvé que les trois gènes var3, PF3D7_0100300, PF3D7_0600400 et PF3D7_0937600, sont transcrit dans les stades érythrocytaires de P. falciparum, avec un pic du niveau de la transcription à 16h post- invasion, qui s’arrête immédiatement après 16h post- invasion. La protéine codée par PF3D7_0600400 a pu être détectée à la fois dans le stade trophozoïte tardif et le stade schizonte, tandis que les protéines codées par PF3D7_0100300 et PF3D7_0937600 ne pouvait être détectées, respectivement, qu’au stade trophozoïte final et au stade schizonte. Les gènes var3 de la souche 3D7 de P. falciparum sont donc exprimés de façon différentielle au cours du développement érythrocytaire du parasite.

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          Most cited references 25

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          The large diverse gene family var encodes proteins involved in cytoadherence and antigenic variation of Plasmodium falciparum-infected erythrocytes.

          The human malaria parasite Plasmodium falciparum evades host immunity by varying the antigenic and adhesive character of infected erythrocytes. We describe a large and extremely diverse family of P. falciparum genes (var) that encode 200-350 kDa proteins having the expected properties of antigenically variant adhesion molecules. Predicted amino acid sequences of var genes show a variable extracellular segment with domains having receptor-binding features, a transmembrane sequence, and a terminal segment that is a probable submembrane anchor. There are 50-150 var genes on multiple parasite chromosomes, and some are in clustered arrangements. var probes detect two classes of transcripts in steady-state RNA: 7-9 kb var transcripts, and an unusual family of 1.8-2.4 kb transcripts that may be involved in expression or rearrangements of var genes.
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            Single-step purification of polypeptides expressed in Escherichia coli as fusions with glutathione S-transferase.

            Plasmid expression vectors have been constructed that direct the synthesis of foreign polypeptides in Escherichia coli as fusions with the C terminus of Sj26, a 26-kDa glutathione S-transferase (GST; EC encoded by the parasitic helminth Schistosoma japonicum. In the majority of cases, fusion proteins are soluble in aqueous solutions and can be purified from crude bacterial lysates under non-denaturing conditions by affinity chromatography on immobilised glutathione. Using batch wash procedures several fusion proteins can be purified in parallel in under 2 h with yields of up to 15 micrograms protein/ml of culture. The vectors have been engineered so that the GST carrier can be cleaved from fusion proteins by digestion with site-specific proteases such as thrombin or blood coagulation factor Xa, following which, the carrier and any uncleaved fusion protein can be removed by absorption on glutathione-agarose. This system has been used successfully for the expression and purification of more than 30 different eukaryotic polypeptides.
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              Maternal antibodies block malaria.


                Author and article information

                EDP Sciences
                24 April 2014
                : 21
                : ( publisher-idID: parasite/2014/01 )
                [1 ] Key Laboratory of Zoonosis, Ministry of Education, Institute of Zoonosis, Jilin University Changchun 130062 PR China
                [2 ] Department of Microbiology, Tumour- and Cellular Biology, Karolinska Institutet S-171 71 Stockholm Sweden
                Author notes

                With equal contribution.

                [* ]Corresponding author: cqj@ 123456jlu.edu.cn
                parasite140022 10.1051/parasite/2014019
                © Y. Zhang et al., published by EDP Sciences, 2014

                This is an Open Access article distributed under the terms of the Creative Commons Attribution License ( http://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

                Page count
                Figures: 4, Tables: 2, Equations: 0, References: 32, Pages: 7
                Research Article

                plasmodium falciparum, var gene, pfemp1, expression


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