Molecular mechanisms of lytic bacteriophage infection of enterococci

肠球菌裂解性噬菌体感染的分子机制

基本信息

批准号：
10309178
负责人：
Cydney N Johnson
金额：
$ 3.4万
依托单位：
UNIVERSITY OF COLORADO DENVER
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：
2021-08-01 至 2023-07-31
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/10309178
关键词：
Address Adsorption Alternative Therapies Animals Anti-Bacterial Agents Antibiotic Resistance Antibiotic Therapy Antibiotics Antigens Bacteria Bacterial Infections Bacteriophages Binding Biochemical Biological Assay Biology Blood Circulation Cell Wall Cell membrane Cell surface Cells Cellular biology Clinical Cytolysis DNA DNA Restriction-Modification Enzymes Data Development Enterobacteriaceae Enterococcus Enterococcus faecalis Event Genes Genetic Genome Genomic DNA Goals Hospitals Human Individual Infection Intestines Knowledge Lactococcus Lead Life Lytic Modeling Modification Molecular Multi-Drug Resistance Mutation Nosocomial Infections Outcome Phage Receptors Pharmaceutical Preparations Plasmids Polysaccharides Pseudomonas Publishing Receptor Gene Resistance Sepsis Specificity Streptococcus System Therapeutic Treatment Efficacy Vancomycin Vancomycin Resistance Viral Virion Virulence Factors Virus Work bacterial fitness base candidate selection combat design experimental study fitness genetic approach insight intestinal barrier multi-drug resistant pathogen novel particle pathogen pathogenic bacteria receptor resistance factors secondary infection therapeutic candidate

项目摘要

PROJECT SUMMARY In recent decades there has been a rapid decline in effective antibiotic therapies and an increase in multidrug- resistant (MDR) bacterial infections. One common MDR pathogen is the Gram-positive intestinal bacterium Enterococcus faecalis which resists many antibiotics including “last-line-of-defense” drugs such as vancomycin. MDR enterococci can expand in the intestine in individuals undergoing broad-spectrum antibiotic therapy. This expansion can lead to E. faecalis translocation to the bloodstream, sepsis, and further shedding of the bacterium, thus perpetuating these hospital-acquired infections. One potential strategy to combat MDR enterococci is the use of bacteriophages (phages). Phages are viruses that infect and kill bacteria with high specificity. Phage infection relies on binding to the bacterial cell surface, ejection of phage DNA into the bacterial cell, replication of the phage genome, and viral particle release from the cell. The use of phages as therapeutics raises concern similar to antibiotic use; bacteria will become resistant to infection, diminishing therapeutic efficacy. Thus, before phages can become a standard clinical therapy, we must clearly understand the specific mechanisms used by phages to infect bacteria and how bacteria respond to phage infection. To begin to elucidate the mechanisms used by phages during infection, I challenged E. faecalis with lytic phages and found that the enterococcal polysaccharide antigen is used for initial phage adsorption to various E. faecalis strains, including strains that the phage cannot successfully infect. Along with this, I have shown that the presence of a mobile plasmid in E. faecalis restricts phage infection. The goals of this project are to fill key gaps in our basic knowledge of phage-bacteria interactions and to provide insights into the mechanisms that influence the outcomes of phage infection, which will be beneficial knowledge for applied phage therapies. This project encompasses the following two Specific Aims: Aim 1: Identify the receptor that promotes DNA entry of Epa-dependent phages. This will be addressed through complementary biochemical assays to identify the receptor that promotes phage DNA entry into E. faecalis. Aim 2: Define the genetic basis of endogenous plasmids in restricting enterococcal phage infection. Here, I will use genetic approaches to identify a novel, enterococcal anti-phage restriction mechanism encoded on a mobile plasmid. These experiments will reveal new insights into the mechanisms that dictate enterococcal phage recognition and infection that will ultimately aid in the development of informed phage therapies. In doing so, my results will expand our basic knowledge surrounding enterococcal cell biology during phage infection and potentially identify new targets for anti-enterococcal therapies.

项目概要近几十年来，有效的抗生素疗法迅速下降，而多种药物的使用却在增加。一种常见的 MDR 病原体是革兰氏阳性肠道细菌。粪肠球菌对许多抗生素具有抵抗力，包括“最后一道防线”药物，例如万古霉素。耐多药肠球菌可以在接受广谱抗生素治疗的个体肠道中增殖。这种扩张可能导致粪肠球菌易位到血液中、败血症和进一步脱落。从而使这些医院获得性感染长期存在，这是对抗 MDR 的一种潜在策略。肠球菌是利用噬菌体（噬菌体）感染并杀死细菌的病毒。噬菌体感染依赖于与细菌细胞表面的结合，将噬菌体 DNA 喷射到细菌细胞中。细菌细胞、噬菌体基因组的复制以及病毒颗粒从细胞中的释放。与抗生素的使用类似，治疗方法也会引起人们的担忧，细菌会对感染产生抵抗力，从而减少细菌的数量；因此，在噬菌体成为标准的临床疗法之前，我们必须清楚地了解。噬菌体感染细菌的具体机制以及细菌如何响应噬菌体感染。为了阐明噬菌体在感染过程中使用的机制，我用裂解噬菌体挑战粪肠球菌并发现肠球菌多糖抗原用于噬菌体对各种大肠杆菌的初始吸附。除此之外，我还证明了粪杆菌菌株，包括噬菌体无法成功感染的菌株。粪肠球菌中存在的移动质粒限制了噬菌体感染。该项目的目标是填补关键空白。我们在噬菌体-细菌相互作用的基础知识方面的差距，并提供对噬菌体-细菌相互作用机制的见解影响噬菌体感染的结果，这将是应用噬菌体疗法的有益知识。项目包含以下两个具体目标：目标 1：识别促进 DNA 进入的受体 Epa 依赖性噬菌体的存在将通过补充生化测定来解决。促进噬菌体 DNA 进入粪肠球菌的受体目标 2：确定内源性的遗传基础。在这里，我将使用遗传方法来识别限制肠球菌噬菌体感染的质粒。这些实验将在移动质粒上编码新型肠球菌抗噬菌体限制机制。揭示了肠球菌噬菌体识别和感染机制的新见解，这将最终有助于开发知情的噬菌体疗法。这样做，我的结果将扩展我们的基础。噬菌体感染过程中有关肠球菌细胞生物学的知识，并可能确定新的目标抗肠球菌疗法。