MICA: Does phase variation contribute to virulence and immune evasion of Neisseria meningitidis?

MICA：相变是否会导致脑膜炎奈瑟菌的毒力和免疫逃避？

• 批准号: MR/M020193/1
• 负责人: Christopher Bayliss
• 金额: $ 56.34万
• 依托单位: University of Leicester
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2015
• 资助国家: 英国
• 起止时间: 2015 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=MR%2FM020193%2F1
• 关键词: MICA; Does; phase; variation; contribute

Many bacterial pathogens colonise and persist in our bodies as harmless 'commensals' that do not cause disease. These bacteria persist even though our bodies produce antibodies against exposed structures on their surface. In this proposal, we aim to improve our understanding of how bacteria avoid these antibodies and whether these avoidance mechanisms influence the ability of bacteria to cause disease.Neisseria meningitidis is a bacterium that is a major cause of meningitis and blood-poisoning but is found in 10-30% of people (i.e. 'carriers') as a harmless commensal of the upper respiratory tract. This bacterial species is present on nasal tissues and at the back of the throat where it can persist for up to twelve months despite the generation of antibodies against surface antigens of the bacteria. One way these bacteria avoid deleterious effects of antibodies is by changing the structure or amounts of these surface antigens. These changes are controlled by repetitive DNA tracts, which mutate at high frequencies resulting in alterations in the expression of genes that make these surface antigens. We have shown that persistence of N. meningitidis in the upper respiratory tract is facilitated by high frequencies of mutations in these repetitive DNA tracts causing reductions in expression of some of the surface antigens. As many of these surface antigens help the bacteria to invade tissues and to survive killing by cells and molecules present in blood, this finding has led us to speculate that reductions in expression of surface antigens, due to mutations in repetitive DNA, affects the ability of N. meningitidis to cause blood poisoning and meningitis. We will test this hypothesis by comparing the repetitive DNA tracts in bacterial isolates from patients and carriers. We will also test whether reductions in expression of specific antigens during persistent carriage of N. meningitidis is correlated with the presence of antibodies against that surface antigen.We will use samples from previous studies in volunteers from whom bacterial isolates, serum and saliva extracts were obtained at three or more time points over a six to twelve month time period. Similarly we will use pre-existing collections of N. meningitidis isolates from disease cases. The repetitive DNA tracts of multiple genes will be analysed by sizing of DNA fragments spanning the repetitive region so that we can count the numbers of repeats and then use these numbers to determine whether a gene is expressed. We will examine if a gene changes as the bacteria persist within a carrier and if the genes are in different states in the disease isolates as compared to those of carriers. The amounts of antibodies will be measured using a microassay. For this, protein products of genes will be purified, linked to fluorescent microspheres and incubated with serum. This will result in specific binding of antibodies to the proteins on the microspheres. Antibodies will then be detected with a different fluorescent tag and quantified in a fluorescence detection machine.We anticipate two major outcomes. Firstly, evidence of whether repetitive DNA produces a particular pattern of gene expression that enables N. meningitidis to cause disease. Identification of a 'virulence-associated' pattern would lead to production of novel preventive measures (i.e. vaccines containing these virulence determinants) or management of disease-cases (i.e. identification of sources of infections and rational decisions on when to provide preventive therapeutic treatment to contacts). Secondly, a demonstration that antibodies are driving reductions in expression of N. meningitidis surface antigens in carriers. This finding will indicate that vaccines containing surface antigens could reduce persistence of disease-causing N. meningitidis strains on mucosal surfaces of carriers and would be important for assessing whether Bexsero (the new MenB vaccine) can prevent spread of disease-causing strain.

许多细菌病原体作为无害的“寄生虫”在我们的体内定植并持续存在，不会引起疾病。这些细菌持续存在，即使我们的身体产生抗体，以对抗其表面暴露的结构。在这项提案中，我们的目标是提高我们对细菌如何避免这些抗体的理解，以及这些避免机制是否影响细菌致病的能力。脑膜炎奈瑟氏菌是脑膜炎和血液中毒的主要原因，但在10-30%的人（即“携带者”）中发现，它是上呼吸道的无害寄生虫。这种细菌存在于鼻组织和咽喉后部，尽管产生了针对细菌表面抗原的抗体，但它可以持续长达12个月。这些细菌避免抗体有害作用的一种方法是改变这些表面抗原的结构或数量。这些变化是由重复的DNA片段控制的，这些DNA片段以高频率突变，导致制造这些表面抗原的基因表达的改变。我们证明了N.上呼吸道中的脑膜炎是由这些重复DNA片段中的高频率突变促进的，这些突变导致一些表面抗原的表达减少。由于这些表面抗原中的许多有助于细菌侵入组织并在血液中存在的细胞和分子的杀伤下存活，因此这一发现使我们推测，由于重复DNA的突变，表面抗原表达的减少影响了N.脑膜炎引起血液中毒和脑膜炎。我们将通过比较从患者和携带者分离的细菌中的重复DNA片段来验证这一假设。我们还将检测在持续携带N.脑膜炎与针对该表面抗原的抗体的存在相关。我们将使用来自先前研究的志愿者样本，这些志愿者在6至12个月的时间段内在三个或更多时间点获得细菌分离物、血清和唾液提取物。类似地，我们将使用预先存在的N的集合。从病例中分离的脑膜炎病毒。多个基因的重复DNA束将通过对跨越重复区域的DNA片段进行大小分析，以便我们可以计算重复的数量，然后使用这些数量来确定基因是否表达。我们将检查基因是否随着细菌在携带者中的持续存在而发生变化，以及与携带者相比，疾病分离株中的基因是否处于不同的状态。将使用微量测定法测量抗体的量。为此，基因的蛋白质产物将被纯化，连接到荧光微球上，并与血清一起孵育。这将导致抗体与微球上的蛋白质特异性结合。然后，抗体将用不同的荧光标记进行检测，并在荧光检测仪中进行定量。首先，重复DNA是否产生了一种特定的基因表达模式，使N。脑膜炎引起的疾病。确定“毒力相关”模式将导致产生新的预防措施（即含有这些毒力决定因素的疫苗）或疾病病例管理（即确定感染源和合理决定何时向接触者提供预防性治疗）。第二，证明抗体正在驱动N.携带者的脑膜炎表面抗原。这一发现将表明，含有表面抗原的疫苗可以减少致病的N。脑膜炎病毒株在携带者的粘膜表面，并将是重要的评估是否Bexsero（新的MenB疫苗）可以防止致病菌株的传播。

项目成果

Variable disruption of epithelial monolayers by Neisseria meningitidis carriage isolates of the hypervirulent MenW cc11 and MenY cc23 lineages.

• DOI: 10.1099/mic.0.001305
• 发表时间: 2023-02
• 期刊: MICROBIOLOGY-SGM
• 影响因子: 2.8
• 作者: Dave, Neelam;Albiheyri, Raed S.;Wanford, Joseph J.;Green, Luke R.;Oldfield, Neil J.;Turner, David P. J.;Martinez-Pomares, Luisa;Bayliss, Christopher D.
• 通讯作者: Bayliss, Christopher D.

Genomic Analysis of Serogroup Y Neisseria meningitidis Isolates Reveals Extensive Similarities Between Carriage-Associated and Disease-Associated Organisms.

脑膜炎奈瑟菌 Y 血清群分离株的基因组分析揭示了携带相关生物和疾病相关生物之间的广泛相似性。

• DOI: 10.1093/infdis/jiw008
• 发表时间: 2016
• 期刊: The Journal of infectious diseases
• 作者: Oldfield NJ

PhasomeIt: an 'omics' approach to cataloguing the potential breadth of phase variation in the genus Campylobacter.

• DOI: 10.1099/mgen.0.000228
• 发表时间: 2018-11
• 期刊: Microbial genomics
• 影响因子: 3.9
• 作者: Aidley J;Wanford JJ;Green LR;Sheppard SK;Bayliss CD
• 通讯作者: Bayliss CD

Clustered intergenic region sequences as predictors of factor H Binding Protein expression patterns and for assessing Neisseria meningitidis strain coverage by meningococcal vaccines.

• DOI: 10.1371/journal.pone.0197186
• 发表时间: 2018
• 期刊: PloS one
• 影响因子: 3.7
• 作者: Cayrou C;Akinduko AA;Mirkes EM;Lucidarme J;Clark SA;Green LR;Cooper HJ;Morrissey J;Borrow R;Bayliss CD
• 通讯作者: Bayliss CD

Rapid Transmission of a Hyper-Virulent Meningococcal Clone Due to High Effective Contact Numbers and Super Spreaders.

• DOI: 10.3389/fgene.2020.579411
• 发表时间: 2020
• 期刊: Frontiers in genetics
• 影响因子: 3.7
• 作者: Holmes JC;Green LR;Oldfield NJ;Turner DPJ;Bayliss CD
• 通讯作者: Bayliss CD