Toxoplasma sporozoite genes that determine environmental resistance and invasion of host cells.

弓形虫子孢子基因决定宿主细胞的环境抵抗力和入侵。

• 批准号: 10628015
• 负责人: JEROEN SAEIJ
• 金额: $ 18.97万
• 依托单位: UNIVERSITY OF CALIFORNIA AT DAVIS
• 依托单位国家: 美国
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-05-24 至 2025-04-30
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10628015
• 关键词: Animals; Attenuated Vaccines; Biological Assay; Cells; Cessation of life; Complement; Congenital Abnormality; Cyst; Cytoplasm; Data; Defect; Desiccation; Disease; Disease Outbreaks; Droughts; Embryonic Development; Environment; Epithelial Cells; Eye diseases; Feces; Felis catus; Fetus; Food Supply; Freezing; Gene Proteins; Genes; Genetic; Human; Immunocompromised Host; In Vitro; Infection; Infection prevention; Ingestion; Invaded; Knock-out; Life; Livestock; Meat; Mus; Names; Oocysts; Oral; Organism; Parasites; Pathology; Pregnant Women; Procedures; Proteins; Resistance; Risk; Role; Serology; Sheep; Source; Sporozoites; Testing; Tissues; Toxoplasma; Toxoplasma gondii; Toxoplasmosis; Vaccination; Vaccine Design; Vaccines; Zoonoses; abortion; acute infection; attenuation; congenital infection; environmental stressor; extracellular; foodborne; foodborne illness; gene product; in vivo; intestinal epithelium; pathogen; prevent; stressor; transmission process; vaccine access; vaccine discovery

Project Summary The parasite Toxoplasma gondii can cause severe disease in immunocompromised patients and fetuses and is the second leading cause of foodborne deaths in the USA. Infection starts after ingestion of oocysts shed in cat feces or after ingestion of meat contaminated with tissue cysts. Oocysts are extremely stable in the environment, resistant to the most inactivation procedures, and highly infectious. Because livestock get infected by sporozoites derived from oocysts, a vaccine based on sporozoites or sporozoite proteins could be effective in protecting livestock and humans. Currently, the only vaccine available is a live attenuated vaccine only approved for use in sheep. However, this vaccine has serious shortcomings as the genetic basis for the attenuation is not known, which poses reversion risks, and it needs to be used immediately once produced because it is based on live tachyzoites, which are not viable for long outside host cells. Despite being a critical step for Toxoplasma transmission, sporozoites inside oocysts are under-studied, largely because they are not cultivatable in vitro and difficult to access in vivo. There is, therefore, a critical need to identify sporozoite gene products that are critical for its invasion of host cells, which could lead to the discovery of vaccine targets. Furthermore, if the genetic basis for the extreme environmental resistance of sporozoites was known it might be possible to exploit this to make other Toxoplasma life stages, such as tachyzoites, or other pathogens more viable extracellularly, which could enhance the shelf-life of vaccines based on live parasites. Our overall objectives are to identify Toxoplasma genes that are specifically involved in the environmental resistance and infectivity of sporozoites. Our central hypotheses are that 1) sporozoite-specific micronemal proteins (MICs) are critical for their invasion into host cells; 2) late embryogenesis abundant proteins (LEAs), which are known to provide resistance to environmental stresses such as drought, high salinity, and freezing in a variety of organisms, determine sporozoite resistance to environmental stressors. In our first aim we will determine the role of LEAs in the protection of sporozoites against environmental stressors. In our second aim we will test the hypothesis that MICs that are specifically expressed in sporozoites are involved in the invasion of host cells. The identification of sporozoite genes that play a role in extracellular survival and attachment/invasion of host cells, will pave the way for designing vaccines that can prevent Toxoplasma infection of humans and animals.

项目概要 寄生虫弓形虫可导致免疫功能低下的患者和胎儿患严重疾病， 是美国食源性死亡的第二大原因。摄入卵囊后开始感染 猫的粪便或摄入被组织囊肿污染的肉后。卵囊在体内极其稳定 环境，对大多数灭活程序具有抵抗力，并且具有高度传染性。因为牲畜得到 被源自卵囊的子孢子感染，基于子孢子或子孢子蛋白的疫苗可以是 能有效保护牲畜和人类。目前，唯一可用的疫苗是减毒活疫苗 仅批准用于绵羊。然而，这种疫苗作为疫苗的遗传基础存在严重缺陷。 衰减未知，存在返原风险，生产后需立即使用 因为它是基于活的速殖子，而这种速殖子不能在宿主细胞外长期存活。尽管是批评者 作为弓形虫传播的一步，卵囊内的子孢子尚未得到充分研究，主要是因为它们不 体外可培养，体内难以获得。因此，迫切需要鉴定子孢子基因 对于其入侵宿主细胞至关重要的产品，这可能导致疫苗靶点的发现。 此外，如果知道子孢子极端环境抵抗力的遗传基础，那么它可能 有可能利用这一点使其他弓形虫生命阶段，例如速殖子或其他病原体更容易 在细胞外具有活性，这可以延长基于活寄生虫的疫苗的保质期。我们的整体 目标是确定专门参与环境抗性和抗性的弓形虫基因 子孢子的传染性。我们的中心假设是 1) 子孢子特异性微线蛋白 (MIC) 对于它们侵入宿主细胞至关重要； 2) 晚期胚胎发生丰富蛋白（LEAs），这是已知的 提供对干旱、高盐度和冰冻等环境胁迫的抵抗力 生物体，决定子孢子对环境压力的抵抗力。在我们的第一个目标中，我们将确定 LEA 在保护子孢子免受环境压力方面的作用。在我们的第二个目标中，我们将测试 假设子孢子中特异性表达的 MIC 参与宿主细胞的侵袭。 鉴定在宿主细胞外存活和附着/入侵中发挥作用的子孢子基因 细胞，将为设计预防人类和动物弓形虫感染的疫苗铺平道路。