Sage specific host cell infection mechanism of malarial parasite

该项目在这三年中的执行情况总结如下。疟疾寄生虫是通过按蚊传播的。寄生虫和子孢子侵入并穿过蚊虫的肠道上皮细胞和唾液腺细胞，通过性融合在蚊子中肠腔内形成，穿过中肠上皮，在肠壁上形成卵囊。蚊虫叮咬注入宿主的唾液腺子孢子必须通过皮肤屏障和肝窦细胞层到达并感染肝细胞。我们计划研究寄生虫入侵这些屏障细胞的分子机制。为此，我们以一种鼠类疟疾寄生虫伯氏疟原虫为模型动物，分析了动子和子孢子的EST(表达序列标签)。我们根据EST中的标准选择基因，产生的寄生虫扰乱了基因。通过对基因中断寄生虫的表型分析，研究了该基因的功能。结果，我们确定MAOP和MAEBL是侵袭MIG-肠道上皮细胞和唾液腺细胞的必需分子。我们还鉴定了两个分子SPECT1和SPECT2，它们是必需分子侵入肝脏血窦细胞层的Kupffer细胞。我们从动子和子孢子中鉴定出OSM-1，这是一种通过中肠细胞和库普弗细胞转运所必需的分子。我们展示了动子和子孢子细胞通过屏障细胞层、蚊子中肠细胞和正弦细胞层的共同机制。我们还演示了子孢子首先通过肝窦层中的枯否细胞到达肝细胞，从而从肝窦感染。

The summary of this project performed in this three years is shown below. Malarial parasite is transmitted by Anopheline mosquito. Parasite ookinete and sporozoite invade and pass through the mosquito mig-gut epithlium cell and the salivary gland cell, and formed in the mosquito mid gut lumen by sexual fusion passes through the mid-gut epithelium and forms a oocyst on the gut wall Salivary gland sporozoite injected into the host by mosquito bite has to pass through the skin barriers and lliver sinusoidal cell layer to reach and infect the hepatocyte. We planned to investigate the molecular mechanisms of the parasite invasion into those barrier cells. For this purpose, we used a rodent malarial parasite Plasmodium berghei as a model animal, and analyzed the EST (expressed sequence tags) of ookinete and sporozoite. We selected gene by a criteria from the EST and generated parasite disrupted the gene. A function of the gene was studied by the analyses of the phenotype of the gene disrupted parasite. As results, we identified MAOP and MAEBL for essential molecules for invasion to mig-gut epithelial cell and the salivary gland cell. And we also identified two molecules, SPECT1 and 2 for essential molecules to invade int the Kupffer cell in the sinusoidal cell layer of the liver. We identified OSM-1, a molecule essential for translocation through the mid-gut cell and Kupffer cell from the ookinete and sporozoite. We demonstrated the common mechanisms of the cell passage of ookinete and sporozoite through the barrier cell layer, the mosquito mid-gut cell and the sinusoidal cell layer. We also demonstrated first for the sporozoite to pass through the Kupffer cell in the sinusoidal layer to reach the hepatocyte to infect from the sinusoid.