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Deciphering molecular mechanisms underlying vertical transmission of Listeria monocytogenes

破译单增李斯特菌垂直传播的分子机制

基本信息

批准号：
10664028
负责人：
Samuel Eallonardo
金额：
$ 5.27万
依托单位：
UNIVERSITY OF ILLINOIS AT CHICAGO
依托单位国家：
美国
项目类别：
财政年份：
2021
资助国家：
美国
起止时间：
2021-08-20 至 2024-12-20
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/10664028
关键词：
5&apos Untranslated Regions Abscess Adult Affinity Amino Acids Bacteria Behavior Binding Blood Cardiac Cell Wall Cells Clinical Communicable Diseases Data Diagnosis Disease Elderly Environment Exhibits Fetal Death Fetal Tissues Fetus Flow Cytometry Fluorescence Microscopy Frequencies Gastroenteritis General Population Genetic Genetic Variation Goals HIV Seropositivity Health Health Benefit Heart Immune response Immune signaling Immunity Immunocompromised Host Immunohistochemistry In Situ Hybridization Individual Infection Inflammatory InlB protein Invaded Knowledge Life Style Listeria monocytogenes Listeriosis Mammalian Cell Membrane Proteins Modeling Molecular Morbidity - disease rate Mothers Mus Nature Neonatal Nucleotides Organ Organism Outcome Outcome Study Pathogenesis Pathology Patients Persons Phenotype Placenta Predisposition Pregnancy Complications Pregnancy loss Pregnant Women Production Public Health Receptor Signaling Ribosomes Severities Signal Transduction Surface Transcript Translations Tropism Variant Vertical Transmission Virulence Factors abortion cell type cytokine design experience experimental study fetal fetal infection fetal loss foodborne foodborne pathogen gut colonization immune activation improved infection risk insight intestinal epithelium knowledgebase model organism mortality novel pathogen placental infection posttranscriptional pregnant prevent protein expression protein function receptor binding tool transmission process

项目摘要

Abstract Pregnant women are more likely to be infected with the intracellular pathogen Listeria monocytogenes (Lm) than the general population, and the bacterium can be vertically transmitted leading to fetal infection and pregnancy loss. Despite its public/health/relevance, the determinants of maternofetal transmission remain undefined. Examination of clinical Lm isolates indicates that subpopulations of strains possess an enhanced ability for vertical transmission. One of these strains, 07PF0776, was first noted for its ability to target the heart, and this cardiotropism requires InlB, a bacterial surface protein known to be important for the invasion of mammalian cells. Experimental evidence indicates that InlB is similarly required for vertical transmission and that high InlB expression alone is sufficient to significantly enhance vertical transmission in an unrelated strain. The goal for this project is to elucidate the mechanisms by which InlB enhances the vertical transmission of hypervirulent Lm strains and of Lm generally. The project aims are designed to connect strain-specific genetic variations to altered bacterial behavior, host pathology, and immune responses. The current working hypothesis is that enhanced translation of inlB occurs in Lm hypervirulent subpopulations as the result of a trinucleotide substitution in the 5’ untranslated region (UTR) of the inlB transcript that promotes ribosome binding. It is also hypothesized that amino acid variations within InlB enhance InlB binding to the bacterial cell wall and thus increase InlB surface abundance. Aim 1 will determine how InlB levels are altered in 07PF0776 by looking at InlB synthesis, degradation, and cell wall affinity. This aim will also explore how the 5’ UTR contributes to increased protein expression. Aim 2 will determine how increased InlB expression promotes bacterial colonization of the placenta and fetus. Experiments will use pregnant mice as a model and compare strains with varying levels of InlB activity. Fluorescence microscopy combined with immuno-histochemistry will determine if InlB-high-expressing strains have enhanced invasion of specific placental cell types, or alternatively gain access through new portals of entry. RNAScope in situ hybridization and flow cytometry will establish how bacterial localization impacts the nature of the placental immune response. The ultimate goal of the above aims will be to establish the mechanisms by which strains of Lm cause severe fetal and neonatal disease. These studies may eventually allow for improved treatment of severe Lm infection and more effective strategies to protect pregnant women from Lm-induced pregnancy complications.

摘要孕妇比一般人群更容易感染细胞内病原体单核细胞增生李斯特菌（Lm），并且该细菌可以垂直传播，导致胎儿感染和妊娠失败。尽管其公共/健康/相关性，母婴传播的决定因素仍然不确定。临床Lm分离株的检查表明菌株亚群具有增强的垂直传播能力。这些菌株之一，07 PF 0776，首先注意到其靶向心脏的能力，这种向心作用需要InlB，一种已知对哺乳动物细胞入侵很重要的细菌表面蛋白。实验证据表明，InlB类似地是垂直传播所需的，并且单独的高InlB表达足以显著增强不相关菌株中的垂直传播。该项目的目标是阐明InlB增强高毒力Lm菌株和Lm的垂直传播的机制。该项目旨在将菌株特异性遗传变异与改变的细菌行为，宿主病理学和免疫反应联系起来。目前的工作假设是，由于inlB转录物的5'非翻译区（UTR）中促进核糖体结合的三核苷酸取代，inlB的翻译增强发生在Lm高毒力亚群中。还假设InlB内的氨基酸变异增强InlB与细菌细胞壁的结合，从而增加InlB表面丰度。目的1将通过观察InlB合成、降解和细胞壁亲和力来确定07 PF 0776中InlB水平如何改变。该目标还将探索5' UTR如何有助于增加蛋白质表达。目的2将确定InlB表达增加如何促进胎盘和胎儿的细菌定植。实验将使用怀孕小鼠作为模型，并比较具有不同水平的InlB活性的菌株。荧光显微镜与免疫组织化学相结合将确定InlB高表达菌株是否增强了对特定胎盘细胞类型的侵袭，或者通过新的入口进入。RNAScope原位杂交和流式细胞术将确定细菌定位如何影响胎盘免疫应答的性质。上述目标的最终目标将是建立Lm菌株引起严重胎儿和新生儿疾病的机制。这些研究最终可能会改善严重Lm感染的治疗，并采取更有效的策略保护孕妇免受Lm引起的妊娠并发症。