Comparative and functional genomics of Toxoplasma and Hammondia hammondi

弓形虫和 Hammondia hammondi 的比较和功能基因组学

• 批准号: 9282262
• 负责人: JON P BOYLE
• 金额: $ 35.73万
• 依托单位: UNIVERSITY OF PITTSBURGH AT PITTSBURGH
• 依托单位国家: 美国
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-06-15 至 2020-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9282262
• 关键词: AIDS/HIV problem; Address; Adult; Animals; Binding Proteins; Biological Assay; Biology; Candidate Disease Gene; Collaborations; Complement; Crete; Cyst; Data; Development; Disease; Eukaryota; Evolution; Fetus; Funding; Gene Deletion; Genes; Genetic; Genetic Transcription; Genome; Goals; Growth; Growth and Development function; Guanosine Triphosphate Phosphohydrolases; Histologic; Histology; Human; Immune; Immune response; Immunocompromised Host; Immunohistochemistry; In Vitro; Individual; Infection; Innate Immune Response; Intuition; Kinetics; Knockout Mice; Molecular; Mouse Strains; Mus; Mutation; Oocysts; Oral; Orthologous Gene; Parasites; Pathogenesis; Pathogenicity; Patients; Phenotype; Play; Positioning Attribute; Publishing; Regulator Genes; Resistance; Role; Serum; Sporozoites; Synteny; System; Testing; Time; Tissues; Toxoplasma; Toxoplasma gondii; Toxoplasmosis; Transplant Recipients; Vacuole; Virulence; Virulence Factors; Virulent; Work; base; comparative; comparative genomics; cytokine; experience; experimental study; functional genomics; guanylate; in vivo; insight; pathogen; programs; public health relevance; response; success; transcription factor; transcriptome; transcriptome sequencing

 DESCRIPTION (provided by applicant): Toxoplasma gondii is an important opportunistic pathogen of humans where it can cause severe disease in the developing fetus, immunocompromised individuals, and in certain cases healthy adults. In contrast the nearest extant relative of T. gondii, Hammondia hammondi, does not infect humans and is highly avirulent in mice, and experimental infections are characterized by rapid conversion to "terminally differentiated" cyst stages. These in vivo virulence differences are recapitulated in vitro, where H. hammondi spontaneously converts into a terminally differentiated cyst stage. We have extensive published and unpublished preliminary data demonstrating that T. gondii and H. hammondi share >99% of their genes in nearly perfect synteny, and that the T. gondii and H. hammondi transcriptomes during development are similar but have key differences in the transcription of multiple candidate virulence effectors and transcription factors. In the work outlined in this 3 year R01 proposal we use the T. gondii/H. hammondi system to identify the gene regulatory mechanisms that drive T. gondii pathogenesis, with a particular focus on bradyzoite cyst stages that are the leading cause of severe toxoplasmosis in HIV/AIDS and transplant patients. In Aim 1 we use ultra-deep, strand-specific RNAseq at time points that encompass clear developmental transitions during in vitro growth to identify genes and genetic networks that regulated in a species-specific manner. In doing so we will identify 1) putative secreted virulence effectors and 2) transcription factors that are uniquely expressed in one species over the other. We will then determine their role in T. gondii biology using gene deletion and cross-species complementation experiments. Success of this Aim is facilitated by extensive published and preliminary data comparing the genomes, in vitro growth rates, transcription profiles, and host responses to T. gondii and H. hammondi. In Aim 2 we address the role of the host in species-specific growth phenotypes. To do this we will compare 1) infection dynamics of T. gondii and H. hammondi in vivo using parallel histological assays to identify differences in the cellular and humoral immune response and 2) the overall infectivity and virulence of H. hammondi in innate-immune deficient mouse strains that are highly susceptible to T. gondii infection. Through these studies we will identify new T. gondii secreted effectors and transcription factors that underlie the dramatic phenotypic differences between these species, and how these effectors might impact the host response to infection. These studies should also more broadly impact our understanding of how, on a gene- by-gene basis, virulent pathogens emerge from comparatively avirulent phenotypic backgrounds.

 描述（由适用提供）：弓形虫弓形虫是人类的重要机会性病原体，在发育中的胎儿，免疫受损的个体以及在某些情况下健康的成年人中，它会引起严重的疾病。相比之下，gondii的最接近的极端亲戚，hammondia hammondi，不感染人类，并且在小鼠中高度无毒，实验感染的特征是快速转化为“末端分化”的囊肿阶段。这些体内病毒差异在体外被概括，其中Hammondi的H. hammondi赞助将其转化为末端分化的囊肿阶段。我们已经发表了广泛的发表和未发表的初步数据，表明T. gondii和H. hammondi在几乎完美的同义中占99％的基因> 99％，并且在发育过程中的T. gondii和H. hammondi转录组相似，但在多种候选病毒效应和转录因子的转录方面具有关键差异。在此3年R01提案中概述的工作中，我们使用T. gondii/h。 Hammondi系统确定驱动T. gondii发病机理的基因调节机制，特别关注铁核囊肿阶段，这是HIV/AIDS和移植患者严重弓形虫病的主要原因。在AIM 1中，我们在涵盖体外生长过程中清晰发育过渡的时间点上使用超深，链特异性的RNASEQ，以鉴定以物种特异性方式调节的基因和遗传网络。在此过程中，我们将确定1）假定的分泌病毒作用和2）在一个物种中唯一表达的转录因子而不是另一个物种。然后，我们将使用基因缺失和跨物种完成实验来确定它们在T. gondii生物学中的作用。该目标的成功是通过大量发布和初步数据来制定的，该数据比较了基因组，体外生长速率，转录曲线以及对T. gondii和H. hammondi的宿主反应。在AIM 2中，我们解决了宿主在特定规格特异性生长表型中的作用。为此，我们将比较1）使用平行的组织学评估来鉴定体内的gondii和H. hammondi的感染动力学，以鉴定 细胞和体液免疫响应以及2）在先天免疫缺陷的小鼠菌株中，哈蒙迪H. hammondi的总体感染和病毒非常容易受到T. gondii感染的影响。通过这些研究，我们将确定新的T. gondii分泌的效果和转录因子，这些因素是这些物种之间显着的表型差异的基础，以及这些作用如何影响宿主对感染的反应。这些研究还应更广泛地影响我们对基因基础上如何从相对无毒的表型背景中出现的有毒病原体的理解。