Department of Pathology, Albert Einstein College of Medicine, Bronx, New York, USA.
Department of Pathology, Albert Einstein College of Medicine, Bronx, New York, USA
mSphere. 2020 Feb 19;5(1):e00100-20. doi: 10.1128/mSphere.00100-20.
causes a chronic infection that affects a significant portion of the world's population, and this latent infection is the source of reactivation of toxoplasmosis. An attribute of the slowly growing bradyzoite stage of the parasite is the formation of a cyst within infected cells, allowing the parasite to escape the host's immune response. In this study, a new bradyzoite cyst atrix ntien (MAG) was identified through a hybridoma library screen. This cyst matrix antigen, atrix ntien 2 (MAG2), contains 14 tandem repeats consisting of acidic, basic, and proline residues. Immunoblotting revealed that MAG2 migrates at a level higher than its predicted molecular weight, and computational analysis showed that the structure of MAG2 is highly disordered. Cell fractionation studies indicated that MAG2 was associated with both insoluble and soluble cyst matrix material, suggesting that it interacts with the intracyst network (ICN). Examination of the kinetics of MAG2 within the cyst matrix using fluorescence recovery after photobleaching (FRAP) demonstrated that MAG2 does not readily diffuse within the cyst matrix. Kinetic studies of MAG1 demonstrated that this protein has different diffusion kinetics in tachyzoite and bradyzoite vacuoles and that its mobility is not altered in the absence of MAG2. In addition, deletion of MAG2 does not influence growth, cystogenesis, or cyst morphology. This report expands on the list of characterized cyst matrix proteins. Using fluorescence recovery after photobleaching (FRAP), we have shown that matrix proteins within the cyst matrix are not mainly in a mobile state, providing further evidence of how proteins behave within the cyst matrix. Understanding the proteins expressed during the bradyzoite stage of the parasite reveals how the parasite functions during chronic infection.
弓形虫引起慢性感染，影响世界上很大一部分人口，这种潜伏感染是弓形体病再激活的来源。寄生虫缓慢生长的缓殖子阶段的一个特征是在受感染的细胞内形成囊，使寄生虫能够逃避宿主的免疫反应。在这项研究中，通过杂交瘤文库筛选鉴定了一种新的缓殖子囊基质抗原 atrix ntien (MAG)。这种囊基质抗原 atrix ntien 2 (MAG2) 含有 14 个串联重复序列，由酸性、碱性和脯氨酸残基组成。免疫印迹显示 MAG2 迁移的水平高于其预测的分子量，计算分析表明 MAG2 的结构高度无序。细胞分级分离研究表明 MAG2 与不溶性和可溶性囊基质物质都有关联，表明它与囊内网络 (ICN) 相互作用。使用荧光恢复后光漂白（FRAP）检查 MAG2 在囊基质内的动力学表明，MAG2 不易在囊基质内扩散。对 MAG1 蛋白的动力学研究表明，该蛋白在速殖子和缓殖子空泡中的扩散动力学不同，并且在没有 MAG2 的情况下其流动性不会改变。此外，删除 MAG2 不会影响生长、囊形成或囊形态。本报告扩展了已鉴定的囊基质蛋白列表。通过荧光恢复后光漂白（FRAP），我们已经表明囊基质内的基质蛋白主要不是处于可移动状态，这进一步证明了蛋白质在囊基质内的行为方式。了解寄生虫缓殖子阶段表达的蛋白质揭示了寄生虫在慢性感染期间的功能。
