The genetic basis of divergence in immune defense between species

所有的生物体都会生病，但有些比另一些更严重。这在一个物种内是正确的(有些人类比其他人类更容易受到某些感染)，但在物种之间也是如此(类人猿不容易受到人类遭受的感染)。这些差异很可能是遗传的。事实上，我们知道参与抗感染能力的基因在物种之间进化得很快--有时是整个基因组中进化最快的基因。然而，我们最缺乏的是对允许某些物种比其他物种更好地抗击感染的基因的清楚了解。这项研究的目的是以果蝇为模型，研究近缘物种之间的免疫防御差异。这项研究具有重要的基础科学意义和实用价值。由于免疫基因正在快速进化，这种方法允许在遗传和分子水平上研究物种之间的进化差异。在应用层面上，这种对抗新感染的快速进化可能会产生其他后果，比如增加自身免疫性疾病的风险。因此，了解不同物种是如何进化来对抗感染的，将有助于阐明人类和其他生物如何必须仔细调整自己的免疫反应来对抗感染，同时又尽可能减少对自己的伤害。这项工作还将为高中生、本科生和研究生提供培训机会。该项目利用几种果蝇来研究不同物种之间的免疫防御差异。这些物种与黑腹果蝇关系密切，许多先天免疫的基本租户都是在那里发现的。这使得研究人员可以解决几个问题：是否有些物种通常比它们的近亲物种更擅长对抗感染？或者，免疫防御更具病原体特异性，是宿主暴露史的结果？针对病原体的免疫防御差异涉及哪些基因？这些基因是不同病原体共有的，还是特定病原体特有的？参与免疫分化的基因是否如基因组数据所预测的那样在正选择下进化？第一个目标是了解相关物种在对抗细菌、真菌和病毒感染方面的能力有何不同。有了这些知识，研究人员将使用两种互补的遗传方法来剖析这些差异的遗传基础：数量性状基因座定位和等位基因特异性基因表达分析。最后，研究人员将通过对不同物种进行基因操作来确认发现--使用CRISPR/Cas9编辑在物种之间移动基因，以确定这些基因是否能拯救强大的免疫反应。这一奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

All organisms get sick, but some get sicker than others. This is true within a species (some humans are more susceptible to certain infections than other humans), but it is also true between species (apes are not susceptible to infections that humans suffer from). These differences are likely to be genetic. In fact, we know that genes involved in the ability to fight infection are fast evolving between species – sometimes the fastest evolving genes across the entire genome. What we mostly lack, however, is a clear understanding of the genes that allow some species to fight infection better than others. This research aims to study how immune defense differs among closely related species using Drosophila as a model. This research is important for both basic scientific and applied reasons. Since immune genes are rapidly evolving, the approach allows for the study of evolutionary divergence between species at the genetic and molecular level. At the applied level, such rapid evolution to fight new infections might have other consequences such as an increased risk of autoimmune disease. So, understanding how different species evolve to fight infection will help elucidate how humans and other organisms must carefully tune their immune responses to fight infection, but also do as little harm to themselves as possible. The work will also provide training opportunities for high school students, undergraduates and graduate students. The project utilizes several Drosophila species to study how immune defense diverges between species. These species are closely related to Drosophila melanogaster, where much of the basic tenants of innate immunity were discovered. This allows the researchers to address several questions: Are some species generally better at fighting infection than their related species? Or is immune defense more pathogen-specific and the result of the history of host exposure? What are the genes involved in the divergence in immune defense against pathogens? Are these genes shared for different pathogens or specific for specific pathogens? Are the genes involved in immune divergence evolving under positive selection as is predicted by the genomic data? The first goal is to understand how related species differ in their ability to fight bacterial, fungal and viral infections. With that knowledge, researchers will dissect the genetic underpinnings of those differences using two complementary genetic approaches: quantitative trait locus mapping and allele specific gene expression analysis. Finally, researchers will confirm findings by genetically manipulating the different species – using CRISPR/Cas9 editing to move genes between species to determine whether those genes rescue a robust immune response.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.