The Adhesin Complex Protein (ACP) of Neisseria meningitidis: vaccine potential and biological properties

脑膜炎奈瑟菌（男性）在世界范围内引起脑膜炎和败血症。最重要的致病原因是A、B、C、W135和Y群脑膜炎球菌。幸运的是，现在有了预防A、C、W135和Y群脑膜炎球菌的疫苗，这些疫苗是基于将这些生物体的糖衣分离出来，并将它们与白喉或破伤风等普通疫苗连接起来，形成结合物。在引进这些疫苗的国家，这些疫苗几乎消除了疾病，例如在英国和美国，C类疾病的发病率降低了95%以上。疫苗能够在人体内诱导抗体，从而杀死微生物，从而提供保护。然而，这种糖衣结合策略对B型脑膜炎球菌（MenB）不起作用，因为B型糖衣不能产生杀死生物体的抗体，而且它与人类蛋白质有相似之处，所以任何使用MenB糖衣生产的疫苗都是有问题的。还有其他选择吗？多年来，奈瑟菌研究团体一直在探索MenB糖衣下面的膜，试图识别那些可以诱导能够杀死MenB细菌的抗体的结构或蛋白质。已经使用了几种技术，例如分析生物体的遗传组成（“反向疫苗学方法”），分析膜结构（“蛋白质组学”，“结构疫苗学”方法）和人类对生物体感染或定植的反应（“免疫蛋白质组学”方法）。反向疫苗学方法现已开发出第一代确定的b型脑膜炎疫苗，称为Bexsero/4CMenB（最近获得了欧洲药品管理局的积极意见）。该疫苗含有3种蛋白质，与新西兰用于控制疾病的疫苗的膜混合，是寻找b型脑膜炎双球菌通用疫苗的重要一步。但即使这样也不是没有问题：重要的是，据预测，Bexsero只能抵御人群中存在的73%的b型结核菌。那么剩下的27%呢？因此，迫切需要确定生物体的其他成分，这些成分可以提供更广泛的保护，以抵御更多数量的MenB菌株。我们提出的研究是基于我们对可能弥补差异的成分的识别。使用“蛋白质组学”方法，我们在MenB膜中发现了一种称为粘连蛋白复合蛋白（ACP）的蛋白质。我们发现ACP能够在动物体内诱导抗体杀死脑膜炎球菌。重要的是，在200种不同的菌株中，脑膜炎球菌只产生3种不同的ACP蛋白（不像Bexsero中的蛋白质更多变），一种ACP蛋白的抗体可以杀死拥有其他类型ACP的细菌。这就是交叉保护的证明。我们还表明，ACP对生物体粘附在人体细胞上很重要。我们的研究计划是通过收集有关ACP蛋白特性的进一步信息来调查ACP在MenB疫苗中包含的潜力。我们的计划分为两部分：在第一部分（“疫苗潜力”）中，我们将检查在大量的MenB菌株（约600）中是否存在3种以上的ACP蛋白，看看这些菌株是否产生这种蛋白质，并推断ACP的结构。我们还将准备新的以acp为基础的疫苗，在实验室动物中进行测试，看看我们是否能杀死更多种类不同的MenB菌株。在第2部分（“生物学作用”）中，我们将推断ACP如何允许MenB粘附在人体细胞上，并识别所涉及的人体分子，检查ACP是否与其他MenB蛋白一起作用以使其粘附，以及ACP粘附引发人体细胞的哪些反应。总之，我们的提议令人兴奋、雄心勃勃、及时且具有创新性；我们的研究将以我们已经收集到的有希望的结果为基础，并提供确凿的证据，证明ACP应包括在新的b型脑膜炎疫苗中。

Neisseria meningitidis (Men) causes meningitis and septicaemia worldwide. The most important causes of disease are meningococci of groups A, B, C, W135 and Y. Fortunately, vaccines are now available for protection against A, C, W135 and Y and these are based on separating the sugar coat from these organisms and linking them to a common vaccine such as diphtheria or tetanus to form a conjugate. These vaccines have virtually eliminated disease in those countries that have introduced them, e.g. in the UK and US the reduction in group C disease has been >95%. Protection is provided by the ability of the vaccines to induce antibodies in humans that can kill the organisms. However, this sugar coat-conjugate strategy will not work for B meningococci (MenB), because the B sugar coat is poor at generating antibodies that can kill the organism and moreover it shares similarities with human proteins, so any vaccine produced using the MenB sugar coat would be problematical. What are the alternatives? For many years, the Neisseria research community has probed the membrane underneath the MenB sugar coat to try and identify those structures or proteins that can induce antibodies capable of killing MenB bacteria. Several techniques have been used, e.g. analyzing the genetic make-up of the organism (the 'reverse vaccinology approach'), analyzing the structure of the membrane (the 'proteomic', 'structural vaccinology' approach) and the human response to infection or colonization by the organism (the 'immuno-proteomic' approach). The reverse vaccinology method has now developed the first generation of defined MenB vaccines, called Bexsero/4CMenB (recently received positive opinion from the European Medicines Agency). This vaccine contains 3 proteins mixed with the membrane from a vaccine used to control disease in New Zealand and is a major step in finding a universal vaccine for MenB. But even this is not without problems: importantly, it is predicted that Bexsero will only protect against 73% of the MenB organisms present in the population. So what about the remaining 27%? Thus, there is a pressing need to identify other components of the organism that can provide broader protection against a larger number of MenB strains. Our proposed research is based on our identification of a component that may make up the difference. Using the 'proteomic' approach we identified a protein in the MenB membrane called the Adhesin Complex Protein (ACP). We show that ACP is able to induce antibodies in animals that can kill meningococci. Importantly, meningococci produce only 3 different ACP proteins in a collection of 200 different strains (unlike the proteins in Bexsero which are more variable) and antibodies to one ACP protein can kill bacteria that possess other types of ACP. This is proof of cross-protection. We also show that ACP is important for the organism to stick to human cells. Our research plans are to investigate the potential of ACP for MenB vaccine inclusion by gathering further information on the properties of this protein. We have a two-part plan to do this:In Part 1 ('the vaccine potential'), we will examine whether there are more than 3 types of ACP proteins in a larger number of MenB strains (~600), look to see if these strains produce the protein and also deduce the structure of ACP. We will also prepare new ACP-based vaccines for testing in laboratory animals to see if we can kill a larger variety of different MenB strains.In Part 2 ('the biological role'), we will deduce how ACP allows MenB to stick to human cells and identify the human molecules involved, examine whether ACP works with other MenB proteins to enable sticking and what responses by human cells are triggered by ACP sticking.In summary, our proposal is exciting, ambitious, timely and innovative; our research will build on the promising results we have already collected and provide conclusive proof that ACP should be included in new MenB vaccines.