Genetics of Cryptosporidium parvum

隐孢子虫中控制毒力表型的基因尚不清楚，但需要鉴定它们以指导药物的开发，更好地了解发病机制，并改善基因组的注释。本项目的目的是应用遗传学方法定位控制C.小的与最初供资期间使用的连锁分析相反，我们建议采用连锁群选择，这是一种不需要克隆来自实验杂交的后代系的策略。相反，控制可选择性状的遗传基因座通过杂交两个表型不同的C。parvum株系，将未克隆的后代群体暴露于一轮或多轮选择压力，并批量对后代群体进行定量基因分型。基于表型之间的差异亲本线，我们将选择早期卵囊分化，卵囊抗漂白剂，和寄生虫感染干扰素？基因敲除小鼠在选择过程中，携带赋予所选择的表型的等位基因的寄生虫将从后代中消除。作为减数分裂重组的结果，来自敏感亲本的等位基因的比例在接近被选择的基因座处将是低的，从而产生“选择谷”。通过用一组单核苷酸多态性对选择的和对照后代群体进行定量基因分型来鉴定这些谷。

Genes controlling virulence phenotypes in Cryptosporidium parasite are unknown, but their identification is needed to guide the development of drugs, to better understand pathogenesis, and to improve the annotation of the genome. The objective of this project is to apply genetic methods to map genes controlling specific phenotypes in C. parvum. In contrast to linkage analysis used in the initial funding period, we propose to apply Linkage Group Selection, a strategy which does not require the cloning of progeny lines derived from experimental crosses. Instead, genetic loci controlling selectable traits are identified by crossing two phenotypically distinct C. parvum lines, exposing uncloned progeny populations to one or multiple rounds of selective pressure, and quantitatively genotyping progeny populations in bulk. Based on phenotypic differences between the parental lines, we will select for early oocyst differentiation, oocyst resistance to bleach, and parasite infectivity to interferon-? knock-out mice. During selection, parasites carrying allele(s) conferring the phenotype selected against will be eliminated from the progeny. As a result of meiotic recombination, the proportion of alleles from the sensitive parent will be low in proximity to the locus under selection, creating a "selection valley". Such valleys will be identified by quantitatively genotyping a selected and a control progeny population with a panel of single nucleotide polymorphisms.