MICRONEME FUNCTION IN TOXOPLASMA

刚地弓形虫是一种主要的机会性病原体，可在先天性感染的婴儿和免疫功能低下的个体（如艾滋病患者）中引起严重疾病（弓形虫病）。因为它是一种专性细胞内寄生虫，弓形虫必须侵入宿主细胞才能生存和复制。此外，弓形虫的入侵直接导致弓形虫病的病理，因为随后的细胞内复制和出口破坏了受感染的宿主细胞。因此，更好地了解弓形虫的入侵可能会导致基于抑制入侵的弓形虫病治疗的发展。我们最近的研究表明，寄生虫分泌一种叫做微基因组的细胞器对弓形虫的入侵至关重要。因此，本建议的长期目标是阐明微量蛋白的功能，以努力确定治疗弓形虫病的新的潜在靶点。我们将首先关注MIC2，因为我们的研究表明，这种微分子蛋白可能是弓形虫入侵的重要粘附素。具体目的1将是利用RNA反义抑制来测量MIC2对弓形虫入侵宿主细胞和滑行运动的重要性。特异性目的II将使用删除和位点特异性突变来鉴定MIC2上介导细胞粘附的位点。特异性目的III将是鉴定MIC2识别的宿主细胞受体。这些研究将直接导致更好地理解弓形虫入侵宿主细胞的分子机制。

Toxoplasma gondii is a major opportunistic pathogen that causes severe disease (toxoplasmosis) in congenitally infected babies and immunocompromised individuals such as those suffering from AIDS. Because it is an obligate intracellular parasite, T. gondii must invade a host cell to survive and replicate. Furthermore, T. gondii invasion is directly responsible for the pathology of toxoplasmosis, since subsequent intracellular replication and egress destroys the infected host cell. Thus, a better understanding of T. gondii invasion could lead to the development of treatments for toxoplasmosis based on inhibition of invasion. Our recent studies indicate that parasite secretion of organelles called micronemes is essential for T. gondii invasion. Thus, the long-term goal of this proposal is to elucidate the function of micronemal proteins in an effort to identify new potential targets for treating toxoplasmosis. We will begin by focusing on MIC2 because our studies suggest that this micronemal protein likely functions as an important adhesin for T. gondii invasion. Specific Aim I will be to use RNA antisense inhibition to measure the importance of MIC2 for T. gondii invasion of host cells and gliding motility. Specific Aim II will be to use deletion and site-specific mutagenesis to identify the sites on MIC2 that mediate cell adhesion. Specific Aim III will be to identify host cell receptors recognized by MIC2. These studies will directly lead to a better understanding of the molecular mechanisms underlying T. gondii invasion of host cells.