The surface of Toxoplasma tachyzoites is dominated by a family of glycosylphosphatidylinositol-anchored antigens related to SAG1
The surface of Toxoplasma tachyzoites is dominated by a family of glycosylphosphatidylinositol-anchored antigens related to SAG1
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DOI：
10.1128/iai.66.5.2237-2244.1998
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发表时间：
1998-05-01
影响因子：
3.1
通讯作者：
Boothroyd, JC
中科院分区：
文献类型：
--
作者：
Manger, ID;Hehl, AB;Boothroyd, JC
弓形虫（Toxoplasma gondii）是一种顶复门寄生虫，具有复杂的生活史，包括一个快速分裂的无性阶段，称为速殖子，已报道速殖子表面包含五种主要抗原，其中最丰富的被指定为SAG 1（对于表面抗原），其他四种抗原中的至少一种（SAG 3）和另一种最近描述的次要抗原（SRS 1 [用于SAG 1相关序列1]）先前已显示与SAG 1结构相关，为了确定是否存在进一步的SAG 1同源物，我们搜索了弓形虫表达序列标签（EST）数据库，发现了大量对应于至少三个与SAG 1相关的新基因的EST，如SAG 1，这些新的SRS基因编码明显糖基化磷脂酰肌醇锚定的蛋白，其共享几个基序和一组保守的半胱氨酸残基。这个家庭似乎已经出现了分歧，从一个共同的祖先根据选择的整体拓扑结构的保护。免疫荧光法显示，其中两个新基因（SRS 2和SRS 3）的产物在弓形虫速殖子表面表达。目前已鉴定出SAG 1基因家族的10个成员，其中包括上述5种主要表面抗原中的3种和仅在缓殖子中表达的一种抗原。该家族的功能可能是提供与宿主细胞相互作用的冗余受体系统和/或指导限制急性T细胞的免疫应答。弓形虫感染
Toxoplasma gondii is an Apicomplexan parasite with a complex life cycle that includes a rapidly dividing asexual stage known as the tachyzoite, The tachyzoite surface has been reported to comprise five major antigens, the most abundant of which is designated SAG1 (for surface antigen), At least one of the other four (SAG3) and another recently described minor antigen (SRS1 [for SAG1-related sequence 1]) have previously been shown to be structurally related to SAG1, To determine if further SAG1 homologs exist, we searched a Toxoplasma expressed sequence tag (EST) database and found numerous ESTs corresponding to at least three new genes related to SAG1, Like SAG1, these new SRS genes encode apparently glycosylphosphatidylinositol-anchored proteins that share several motifs and a set of conserved cysteine residues. This family appears to have arisen by divergence from a common ancestor under selection for the conservation of overall topology. The products of two of these new genes (SRS2 and SRS3) are shown to be expressed on the surface of Toxoplasma tachyzoites by immunofluorescence, We also identified strain-specific differences in relative expression levels. A total of 10 members of the SAG1 gene family have now been identified, which apparently include three of the five major surface antigens previously described and one antigen expressed only in bradyzoites, The function of this family may be to provide a redundant system of receptors for interaction with host cells and/or to direct the immune responses that limit acute T. gondii infections.