MICRONEME FUNCTION IN TOXOPLASMA

弓形虫是一种主要的机会性病原体，会在先天感染的婴儿和免疫功能受损的人(如艾滋病患者)中引起严重疾病(弓形虫病)。因为它是一种专性的细胞内寄生虫，弓形虫必须入侵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侵袭可能会导致基于抑制侵袭的弓形虫病治疗方法的发展。我们最近的研究表明，寄生虫分泌的细胞器称为微线虫，是弓形虫入侵所必需的。因此，这项提议的长期目标是阐明微线体蛋白的功能，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，这种微体蛋白可能是弓形虫入侵的重要粘附素。具体目的I将是利用RNA反义抑制来衡量MIC2对弓形虫侵袭宿主细胞和滑动运动的重要性。具体目标二将是使用缺失和定点突变来确定MIC2上介导细胞黏附的位点。具体目标三将是识别MIC2识别的宿主细胞受体。这些研究将直接导致对弓形虫入侵宿主细胞的分子机制的更好的理解。

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.