Genetics of Cryptosporidium parvum

小隐孢子虫的遗传学

• 批准号: 6553701
• 负责人: GIOVANNI WIDMER
• 金额: $ 21.9万
• 依托单位: TUFTS UNIVERSITY BOSTON
• 依托单位国家: 美国
• 财政年份: 2002
• 资助国家: 美国
• 起止时间: 2002-07-01 至 2007-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6553701
• 关键词: Cryptosporidium; biotechnology; double stranded RNA; gene targeting; genetic mapping; genetic markers; genetic polymorphism; genetic recombination; genetically modified animals; laboratory mouse; linkage mapping; protozoal genetics; quantitative trait loci; restriction fragment length polymorphism; virulence

DESCRIPTION (provided by applicant): Cryptosporidium parvum infects AIDS patients and other immunodeficient individuals and is a frequent cause of childhood diarrhea. Studies in human volunteers and animals have revealed pronounced differences in virulence among isolates, but the genetic determinants of virulence are unknown. The recent development in our laboratory of a method to cross C. parvum lines in mice opens new possibilitiesfor studying this pathogen using genetic methods. We have found that C. parvum lines with recombinant genotypes are produced in mixed mouse infections and that recombination between different genotypes can produce highly virulent progeny lines. Since multiple recombinant lines with different virulence properties are obtained in experimental crosses, linkage analysis can be used to identify genetic determinants of virulence, without prior knowledge of virulence determinants. It is our central hypothesis that a majority of clinically or biologically relevant phenotypic properties in C. parvum are quantitative traits controlled by multiple genes which can be identified by linkage analysis. Specific Aims: 1. Establish a high-density map of polymorphic genetic markers for C. parvum type 2. The almost completed C. parvum genome sequence will facilitate the identification of polymorphic microsatellites, restriction fragment length polymorphisms and single nucleotide polymorphisms. 2. Determine the mating structure and the inheritance of an extrachromosomal element in genotypically mixed C. parvum infections. We will test the working hypothesis that in mixed C. parvum infections fertilization results from the random fusion of identical or dissimilar gametes, and that the ratio of self- to cross-mating conforms to the model of random mating. The inheritance of a viral RNA genome will be studied in the context of this specific aim. 3. Identify virulence markers in type 2 C. parvum using Quantitative Trait Locus (QTL) analysis. This aim is based on preliminary observations that recombination between C. parvum lines generates progeny with distinct capacities to kill mice. We will test the following two working hypotheses: a) Virulence is determined by multiple genetic loci. b) QTL analysis can be used to identify genomic segments associated with virulence.

描述（由申请人提供）：小隐孢子虫感染艾滋病患者和其他免疫缺陷个体，是儿童腹泻的常见原因。对人类志愿者和动物的研究表明，分离株之间的毒力存在显着差异，但毒力的遗传决定因素尚不清楚。我们实验室最近开发了一种在小鼠中杂交小隐孢子虫系的方法，为利用遗传方法研究这种病原体开辟了新的可能性。我们发现，具有重组基因型的小隐孢子虫系是在小鼠混合感染中产生的，并且不同基因型之间的重组可以产生高毒力的后代系。由于在实验杂交中获得了具有不同毒力特性的多个重组系，因此可以使用连锁分析来鉴定毒力的遗传决定因素，而无需事先了解毒力决定因素。我们的中心假设是，C. parvum 的大多数临床或生物学相关表型特性是由多个基因控制的数量性状，这些基因可以通过连锁分析来识别。具体目标： 1. 建立小隐孢子虫2型多态性遗传标记高密度图谱。目前已基本完成的小隐孢子虫基因组序列将有助于多态性微卫星、限制性片段长度多态性和单核苷酸多态性的鉴定。 2. 确定基因型混合的微小隐球菌感染中染色体外元件的交配结构和遗传。我们将测试以下工作假设：在混合小隐孢子虫感染中，受精是由相同或不同配子的随机融合产生的，并且自交与异交的比例符合随机交配模型。病毒 RNA 基因组的遗传将在这一特定目标的背景下进行研究。 3. 使用数量性状基因座 (QTL) 分析鉴定 2 型小隐孢子虫中的毒力标记。这一目标是基于初步观察，即小隐孢子虫系之间的重组产生了具有不同杀死小鼠能力的后代。我们将测试以下两个工作假设：a）毒力由多个遗传位点决定。 b) QTL 分析可用于识别与毒力相关的基因组片段。