Collaborative Research: How does an intracellular symbiont manipulate host cell biology?

管状沃尔巴克氏体是一种感染大量昆虫的细菌，包括蚊子等重要的人类疾病媒介。这种细菌是母体传播的，已知在昆虫宿主中引起各种影响，包括操纵繁殖和抑制病毒复制。由于沃尔巴克氏体能够抑制病毒在昆虫宿主中的复制，因此它被用于减少人类疾病的传播（所谓的“病原体阻断”）。因此，更好地了解沃尔巴克氏体如何感染宿主并改变宿主细胞生物学是至关重要的。虽然沃尔巴克氏体感染了地球上40%以上的昆虫，但令人惊讶的是，人们对这种细菌操纵宿主的确切机制知之甚少。这主要是由于沃尔巴克氏体发生在宿主细胞内，目前还不能对其进行基因操作。这个项目将在这个系统中使用一种新的方法来鉴定细菌用来改变宿主细胞生物学的蛋白质。通过鉴定和表征这些蛋白质，将了解沃尔巴克氏体的基本生物学和感染过程中利用的宿主细胞成分。结果也将导致其他共生系统的比较分析。来自科学领域代表性不足群体的本科生将接受与沃尔巴克氏体相关的基于项目的研究培训。该项目的首要科学目标是确定一种非常广泛的细菌与其宿主相互作用的机制。沃尔巴克氏体是一种细胞内的α -变形菌，与非常广泛的无脊椎动物，包括等足类动物、线虫和昆虫形成共生关系。沃尔巴克氏体目前是病媒控制方面的兴趣所在，因为携带这种细菌的蚊子不能传播重要的人类疾病。由于沃尔巴克氏体目前是不可培养的或遗传上难以处理的，因此对其与真核宿主相互作用的分子基础知之甚少。沃尔巴克氏体编码IV型分泌系统，并被认为向真核细胞分泌蛋白质（称为“效应器”），以改变其昆虫宿主的生物学特性。本项目将使用一种强有力的方法来识别和研究沃尔巴克氏体中可能的效应物的生化功能。研究人员将通过基因组学和生物信息学鉴定候选效应物。他们将在异源系统中使用酵母基因筛选和分泌试验来进一步识别和表征这些候选者。最后，研究人员将研究这些蛋白在果蝇宿主体内的生化功能和细胞效应。这些结果将是对沃尔巴克氏菌分泌底物的首次全面分析，并将导致沃尔巴克氏菌领域和其他共生菌株（如感染丝虫线虫的菌株）的比较工作取得重大进展。

Wolbachia pipientis is a bacterium that infects a large number of insects, including important human disease vectors such as mosquitos. This bacterium is maternally transmitted and is known to cause a variety of effects in the insect host including manipulation of reproduction and suppression of virus replication. Because Wolbachia is capable of suppressing virus replication in insect hosts, it is being used to decrease the spread of human diseases (so-called "pathogen blocking"). It is critical, therefore, to better understand how Wolbachia infects hosts and alters host cell biology. Although Wolbachia infect upwards of 40% of insects on the planet, there is surprisingly little known about the exact mechanism used by the bacterium to manipulate its host. This is largely due to the fact that Wolbachia occurs inside host cells and cannot be genetically manipulated presently. This project will use a novel approach in this system to identify proteins used by the bacterium to alter host cell biology. By identifying and characterizing these proteins, much will be learned about the basic biology of Wolbachia and the host cell components utilized during infection. Results will also lead to comparative analyses in other symbiotic systems. Undergraduate students from underrepresented groups in science will be trained with project-based research related to this project on Wolbachia.The overarching scientific goal of this project is to identify the mechanisms by which an extraordinarily widespread bacterium interacts with its host. Wolbachia pipientis is an intracellular alpha-proteobacterium that forms symbioses with an extremely broad array of invertebrates, including isopods, nematodes, and insects. Wolbachia is currently of interest with regards to vector control because mosquitoes harboring the bacterium are unable to transmit important human diseases. Because Wolbachia are not currently culturable or genetically tractable, little is known about the molecular basis of interaction with eukaryotic hosts. Wolbachia encodes a type IV secretion system and is thought to secrete proteins (termed "effectors") into the eukaryotic cell to alter the biology of its insect hosts. This project will use a powerful method to identify and study the biochemical function of probable effectors in Wolbachia. The investigators will identify candidate effectors through genomics and bioinformatics. They will use a yeast genetic screen and a secretion assay in a heterologous system to further identify and characterize these candidates. Finally, the researchers will investigate the biochemical function and cellular effects of these proteins in the Drosophila host. These results will be the first comprehensive analysis of Wolbachia secreted substrates and will lead to significant advances in the Wolbachia field and comparative work in other symbiotic strains (such as those infecting filarial nemotodes).