An engineered meningococcal OMV vaccine for Africa against all capsular groups

针对非洲所有荚膜群的工程脑膜炎球菌 OMV 疫苗

• 批准号: 7781483
• 负责人: Dan M. Granoff
• 金额: $ 48.15万
• 依托单位: CHILDREN'S HOSPITAL & RES CTR AT OAKLAND
• 依托单位国家: 美国
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-01-01 至 2013-12-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7781483
• 关键词: Address; Adjuvant; Africa; Africa South of the Sahara; African; Age; Amino Acid Sequence; Anabolism; Antibodies; Antibody Formation; Antigen Targeting; Antigenic Variation; Antigens; Attenuated; Bacteria; Bacterial Adhesins; Binding Proteins; Cells; Child; Collection; Complement; Complement Factor H; Conjugate Vaccines; Cytolysis; Data; Detergents; Developed Countries; Development; Disease; Dose; Encapsulated; Endemic Diseases; Endotoxins; Engineering; Enzyme-Linked Immunosorbent Assay; Epidemic; Flow Cytometry; Genes; Genetic; Genotype; Goals; Human; Immune; Immune Sera; Immunity; Immunization Schedule; Immunoglobulin Variable Region; Immunologic Memory; In Vitro; Incidence; Incubated; Infant; Inflammatory Response Pathway; Institutes; Iron; Laboratories; Licensing; Life; Mass Immunization; Measures; Mediating; Membrane; Membrane Proteins; Meningitis; Meningococcal vaccine; Methods; Monoclonal Antibodies; Mus; Mutation; Neisseria meningitidis; Pathway interactions; Patients; Peripheral Blood Mononuclear Cell; Persons; Phenotype; Polysaccharides; Preparation; Prevalence; Prevention; Prevention strategy; Primates; Proteins; Public Health; Recombinant Proteins; Relative (related person); Research; Safety; Sahara; Sampling; Serological; Serum; Surface; Surface Antigens; Testing; Toxic effect; Vaccine Antigen; Vaccine Design; Vaccines; Variant; Vesicle; Western Blotting; age group; bactericide; base; capsule; disorder prevention; experience; genome sequencing; high risk; immunogenicity; major outer membrane protein; mutant; novel; public health relevance; response; vaccine candidate; vaccine efficacy

DESCRIPTION (provided by applicant): Neisseria meningitidis causes explosive epidemics in sub-Saharan Africa. Most are caused by capsular group A strains. However, group W-135 and X strains also cause epidemics in this region, and these strains may emerge once mass immunization with a group A polysaccharide-protein conjugate vaccine is introduced. Our goal is to develop a meningococcal vaccine for Africa that targets strains from all capsular groups. Our approach will be to use novel protein antigens identified for "group B vaccines", which also elicit protective antibodies against strains with other capsules. These "unconventional" antigens will be presented in simple outer membrane vesicles (OMV) that have potent natural adjuvants. Our studies will build on previous experience with detergent-extracted OMV vaccines, which are proven to be safe and effective in humans. Their major limitation is that they elicit serum bactericidal antibodies primarily directed at PorA, which is antigenically variable. To extend protection to strains with heterologous PorA, we prepared mutants of group B strains that were engineered to over-express factor H binding protein (fHbp), which is a novel antigen in two promising group B recombinant protein vaccines. By introducing an additional mutation in LPS biosynthesis, we attenuated endotoxin activity. In mice, non-detergent-treated OMV vaccines prepared from the mutants elicited serum bactericidal antibody responses against genetically diverse group B strains, as well as epidemic group A, W-135 and X strains from Africa. Our hypothesis is that a native OMV vaccine prepared from mutant strains from Africa will elicit even broader bactericidal antibodies directed at PorA, fHbp and other antigens expressed by strains from Africa. Further, the LPS mutation will eliminate the need for detergent extraction of the OMV, which is used to decrease LPS in conventional OMV vaccines, but also extracts desirable antigens such as fHbp. In Aim 1, we will investigate genetic lineages and sequence diversity of genes encoding fHbp, PorA and other vaccine antigens among 200 meningococcal isolates from a geographically diverse collection of strains from Africa. In Aim 2, we will measure antigen expression by a quantitative capture ELISA, and antigen surface-accessibility on live bacteria by flow cytometry. In Aim 3, we will create mutants of recent African epidemic strains, which will be engineered to express more than one PorA molecule, over-express fHbp, and have attenuated endotoxin. The vaccine strains also will be selected for naturally high expression of an adhesin/invasin, NadA. We will prepare native OMV vaccines from the mutants, and assess OMV toxicity by measuring inflammatory cytokine responses of human PBMCs incubated in vitro with the vaccine. We will immunize mice and infant primates and measure serum bactericidal antibody responses against strains from Africa. The results will provide proof of principle that the OMV vaccine is likely to be well-tolerated in humans and elicit broad protective immunity. These findings would support an application to test the OMV vaccine in humans for control of meningococcal epidemics in sub-Sahara caused by strains from all capsular groups. PUBLIC HEALTH RELEVANCE: Meningococci cause explosive epidemics of meningitis in sub-Sahara Africa that can involve more than 100,000 cases in a few months. Most epidemics have been caused by encapsulated group A strains but strains from other capsular groups also have begun to cause epidemics in the region. A polysaccharide conjugate vaccine against group A disease is being developed for Africa but there is grave concern that strains with other capsules may emerge and cause epidemics once mass immunization with the group A conjugate vaccine is introduced. We propose to develop an outer membrane vesicle vaccine from mutant meningococcal strains, engineered for over-expression of promising protein vaccine antigens, as a universal meningococcal vaccine for Africa against disease caused by strains from all capsular groups.

描述（由申请人提供）：脑膜炎奈瑟菌在撒哈拉以南非洲引起爆炸性流行病。大多数是由荚膜A群菌株引起的。然而，W-135组和X组菌株也在该地区引起流行病，一旦采用a组多糖蛋白结合疫苗进行大规模免疫，这些菌株可能会出现。我们的目标是为非洲开发一种针对所有荚膜群菌株的脑膜炎球菌疫苗。我们的方法将是使用为“B组疫苗”鉴定的新型蛋白抗原，这种抗原也会引发针对其他胶囊菌株的保护性抗体。这些“非常规”抗原将在具有强效天然佐剂的简单外膜囊泡（OMV）中呈现。我们的研究将建立在以前使用洗涤剂提取的OMV疫苗的经验基础上，这些疫苗已被证明对人类安全有效。它们的主要限制是，它们引发的血清杀菌抗体主要针对PorA，这是抗原可变的。为了将保护扩展到具有异源PorA的菌株，我们制备了B组菌株的突变体，该突变体经过工程改造，过表达因子H结合蛋白（fHbp），这是两种有前途的B组重组蛋白疫苗中的一种新抗原。通过在LPS生物合成中引入一个额外的突变，我们减弱了内毒素的活性。在小鼠中，由突变体制备的非洗涤剂处理的OMV疫苗引发了针对遗传多样化的B组菌株以及来自非洲的流行病A组、W-135组和X组菌株的血清杀菌抗体反应。我们的假设是，从非洲突变株制备的本地OMV疫苗将引发针对非洲菌株表达的PorA， fHbp和其他抗原的更广泛的杀菌抗体。此外，LPS突变将消除对洗涤剂提取OMV的需要，这种方法在传统的OMV疫苗中用于减少LPS，但也可以提取所需的抗原，如fHbp。在Aim 1中，我们将调查来自非洲不同地区的200株脑膜炎球菌分离株中编码fHbp、PorA和其他疫苗抗原的基因的遗传谱系和序列多样性。在目标2中，我们将通过定量捕获ELISA检测抗原表达，并通过流式细胞术检测抗原在活菌表面的可及性。在Aim 3中，我们将创建最近非洲流行菌株的突变体，这些突变体将被设计成表达多个PorA分子，过表达fHbp，并且具有减弱的内毒素。疫苗株也将被选择为自然高表达粘连素/入侵素，NadA。我们将从这些突变体中制备原生OMV疫苗，并通过测量与疫苗一起体外培养的人pbmc的炎症细胞因子反应来评估OMV毒性。我们将对小鼠和幼龄灵长类动物进行免疫接种，并测量针对非洲菌株的血清杀菌抗体反应。这一结果将为OMV疫苗在人体中可能具有良好的耐受性并引发广泛的保护性免疫提供原理证明。这些发现将支持在人身上测试OMV疫苗的应用，以控制撒哈拉以南地区由所有荚膜群菌株引起的脑膜炎球菌流行。