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.

项目摘要 在免疫功能强化的患者和胎儿和 是美国食源性死亡的第二大原因。摄入卵囊脱落后感染开始 猫粪便或摄入被组织囊肿污染的肉后。卵囊在 环境，抵抗最灭活程序，并且具有高度感染力。因为牲畜得到 被源自卵囊的孢子虫感染，基于孢子虫或孢子岩蛋白的疫苗可能是 有效保护牲畜和人类。目前，唯一可用的疫苗是活疫苗 仅批准用于绵羊。但是，这种疫苗是严重的缺点，作为遗传基础 衰减尚不清楚，它带来了恢复风险，并且需要立即生产后使用它 因为它基于实时tachyzoites，这对于长时间的外部宿主细胞不可行。尽管很关键 弓形虫传播的步骤，卵囊内部的孢子菌没有研究不足，主要是因为它们不是 可以在体外栽培且难以进入体内。因此，有识别孢子岩基因的迫切需要 对于侵袭宿主细胞至关重要的产品，可能导致发现疫苗靶标。 此外，如果知道Sporozoites极端环境抵抗的遗传基础可能会知道 有可能利用它使其他弓形虫生命阶段，例如tachyzoites或其他病原体 可行的细胞外，可以根据活寄生虫增强疫苗的保质期。我们的整体 目标是识别特异性参与环境抗性和 子孢子的感染力。我们的中心假设是1）孢子岩特异性的微蛋白质（MIC） 对于他们入侵宿主细胞至关重要； 2）胚胎发生晚期丰富的蛋白质（LEAS），已知 提供对环境压力的抵抗力，例如干旱，高盐度和冻结 生物体，确定孢子岩对环境压力源的抗性。在我们的第一个目标中，我们将确定 LEA在保护孢子源侵害环境压力源中的作用。在我们的第二个目标中，我们将测试 假设在孢子菌中专门表达的麦克风参与宿主细胞的侵袭。 在细胞外存活和宿主的附着/侵袭中起作用的孢子岩基因的鉴定 cells, will pave the way for designing vaccines that can prevent Toxoplasma infection of humans and animals.