Genetics and genomics of schistosome resistance in snails

摘要 人类血吸虫寄生虫的传播取决于是否有合适的水生蜗牛 中间主机。如果没有传播血吸虫的蜗牛，或者蜗牛不再支持血吸虫 发展起来，就不会有血吸虫病了。开发针对蜗牛的基因控制计划由来已久 被提倡，但由于缺乏必要的遗传知识和有效的种系操作而受阻 工具。这个项目的目标是开发我们最近开发的遗传和基因组资源，在 与新兴强大技术的应用相结合，以解决 两种钉螺-血吸虫系统中钉螺对血吸虫的抗性 和Bulinus spp.-S.haematobium，它们参与肠道和泌尿生殖系统的传播 血吸虫病分别为。这两个蜗牛-血吸虫系统负责大约99%的 人类血吸虫病在世界上的传播。我们建议采用两个新的蜗牛模型。光滑板- S.mansoni和Bu.以Truncatus-S.haematobium为代表的两个系统进行研究。在目标1中，我们将 应用全基因组测序技术扫描个体的单核苷酸多态(SNPs) 重组近交系(RIL)构建幼年血吸虫抗性高分辨率遗传图谱 和成年毕氏。研究得最好的血吸虫病钉螺模型。RILS是从我们的新品种培育出来的 由两条纯合线组成的模型。光面，一种完全易感，另一种完全 对肠道血吸虫病最重要的病原体曼氏血吸虫的抗药性。在目标2中，我们将 用RNA测序(RNAseq)研究基因组差异表达和等位基因变异 利用我们新开发的遗传资源(即RIL蜗牛及其两个纯合亲本蜗牛)的基因。 对RNAseq数据的综合分析结合在精细抗性基因座中发现的基因将导致 准确识别少量的抗药性候选者，这将用于后续研究， 包括这一目标提出的流行区自然种群中抗性基因的遗传变异。在……里面 目标3，我们将使用功能基因组学和比较基因组学相结合的方法来确定共线区域 毕氏之间。Oberrata和Bu.Truncatus，揭示了布氏血吸虫抗药性的基因组基础。Truncatus， 血瘤链球菌的中间宿主。矛盾的是，血瘤链霉菌尽管是最丰富的 所有感染人类的血吸虫物种，在与其相互作用方面受到的关注很少 蜗牛的寄主。在目标4中，我们将利用RNAi(RNA干扰)和CRISPR(定期聚集 间隔短回文重复)以从功能上验证影响钉螺亲和性的候选基因 曼氏链霉菌或血瘤链霉菌。这项研究将使人们对血吸虫耐药性有更深入的了解 在毕城。首次从分子水平上揭示了支撑牛肝素活性的基因组基础。 从蜗牛到血吸虫，并帮助开发更有效和新的方法来控制血吸虫病。

SUMMARY Transmission of human schistosome parasites depends on availability of suitable aquatic snail intermediate hosts. If no schistosome-transmitting snails are present, or snails no longer support schistosome development, there will be no schistosomiasis. Developing snail-targeted genetic control programs has long been advocated, but hampered by the lack of necessary genetic knowledge and effective germline manipulation tools. The objective of this project is to exploit our recently developed genetic and genomic resources, in combination with application of emerging powerful technologies, to address fundamental mechanisms of schistosome resistance of snails in two snail-schistosome systems, Biomphalaria spp.–Schistosoma mansoni and Bulinus spp.–S. haematobium, which are involved in transmission of intestinal and urogenital schistosomiasis, respectively. The two snail-schistosome systems are responsible for approximately 99% of human schistosomiasis transmission in the world. We propose to employ two new snail models, Bi. glabrata– S. mansoni and Bu. truncatus–S. haematobium to represent the two systems for the study. In Aim 1, we will apply whole genome sequencing (WGS) to scan single nucleotide polymorphisms (SNPs) of individual recombination inbred lines (RILs) to generate high-resolution genetic maps of schistosome resistance in juvenile and adult Bi. glabrata, the best-studied snail model of schistosomiasis. The RILs have been bred from our new model that consists of two homozygous lines of Bi. glabrata, one fully susceptible to, and the other completely resistant to, S. mansoni, the most important causative agent of intestinal schistosomiasis. In Aim 2, we will employ RNA sequencing (RNAseq) to investigate differential expression and allelic variation of genome-wide genes using our newly developed genetic resources (i.e., RIL snails and their two homozygous parent snails). A comprehensive analysis of RNAseq data coupled with genes identified in the fine resistance loci will lead to accurate identification of small number of resistance candidates, which will be used for subsequent studies, including genetic variation of resistance genes in natural populations in endemic areas proposed in this aim. In Aim 3, we will use a combined approach of functional and comparative genomics to identify syntenic regions between Bi. glabrata and Bu. truncatus and reveal the genomic basis of schistosome resistance in Bu. truncatus, an intermediate host of S. haematobium. Paradoxically, S. haematobium, despite being the most abundant of all schistosome species infecting people, has received very little attention with respect to its interactions with its bulinid snail hosts. In Aim 4, we will utilize RNAi (RNA interference) and CRISPR (clustered regularly interspaced short palindromic repeats) to functionally verify the candidate genes affecting snail compatibility to S. mansoni or S. haematobium. This study will lead to a much deeper understanding of schistosome resistance in Bi. glabrata, provide the first molecular insight into the genomic basis underpinning competence of bulinid snails to schistosome, and help develop more effective and novel methods for controlling schistosomiasis.