Immune Dampening the OMPs of non-typeable H. influenzae

描述（由申请人提供）：病毒、细菌和寄生虫新疫苗开发中最具挑战性的一个方面是克服抗原变异的问题。针对引起中耳炎的病原体的疫苗的开发正受到许多团体的大力追求，但由于其抗原多样性，在很大程度上是复杂的。我们对三种主要细菌（不可分型的流感嗜血杆菌（NTHI）、肺炎链球菌和卡他莫拉菌）及其病毒共病原体（流感病毒、鼻病毒、腺病毒等）的致病机制了解不全，对OM期间儿科免疫反应的了解不足，带来了多重独特的挑战。NTHI是儿童中耳炎（OM）的主要细菌病原体，表现出相当大的菌株间差异。主要外膜蛋白（OMP）是血清抗体的主要靶点，也是疫苗研制的重要靶点。免疫学研究一致表明，该抗体定向于OMPs表面环结构中的免疫显性线性表位，这些表位依赖于菌株，经历抗原变异，使儿童不受其他循环NTHI逃逸变体和菌株的保护。对其中两种OMPs， P2和P5蛋白的详细研究表明，这些OMPs的某些区域表现出较少的序列变异。因此，使用从中选择的肽可在免疫后产生更广泛的杀菌抗体。免疫学和生物物理学研究检查了表面概率、亲水性、柔韧性和抗原性图，强烈表明在自然条件下免疫原性较差的蛋白质的其他高度保守区域可能成为免疫原性。

DESCRIPTION (provided by applicant): One of the most challenging aspects of new vaccine development for viruses, bacteria and parasites is overcoming problems of antigenic variation. The development of vaccines against pathogens, which cause otitis media are being vigorously pursued by many groups, but is complicated in a significant way due to their antigenic diversity. Our incomplete understanding of the pathogenic mechanisms used by each of the three major bacterial species (nontypeable Haemophlius influenzae (NTHI), Streptococcus pneumoniae and Moraxella catarrhalis), their viral co-pathogens (Influenza, Rhinovirus, Adenovirus etc) and our inadequate understanding of the pediatric immune response during OM has presented multiple unique challenges. NTHI, a major bacterial pathogen of Otitis Media (OM) in children exhibits considerable strain-to-strain variation. The major outer membrane proteins (OMP) appear to be the major target of serum antibody and important targets of vaccine development. Immunological studies consistently show the antibody is directed to immunodominant, linear epitopes in surface loop structures of the OMPs which are strain dependent, undergo antigenic variation and leave the child unprotected against other circulating NTHI escape variants and strains. Detailed studies of two of these OMPs, the P2 and P5 proteins suggest that some regions of these OMPs exhibit less sequence variation. Thus using selected peptides from this result in the production of more broadly bactericidal antibody following immunization. Immunological and biophysical studies examining surface probability, hydrophilicity, flexibility, and antigenicity plots, strongly suggest that additional, more highly conserved regions of the protein, which are poorly immunogenic under natural conditions, could become immunogenic. Antigenic variation promoted through selective genetic instability is obviously a successful immunological strategy employed by many microbial pathogens. Coupling this to selective and focused immunodominance on the protein structure serves to prevent the immune system from recognizing other antigenic structures on the molecule. These "decoying" epitopes of the OMPs structure results in isolate-, strain- or serotype-specific antibody responses. The host immune system appears fixated on these more visible decoying epitopes at the cost of fully recognizing other conserved and protective epitopes within and between surface protein structures. The objective of this proposal is to further test the technology of immune dampening as a strategy to refocus the immune responses away from immunodominant, non-protective or serotype-restricted epitopes in P2 and P5, towards more broadly protective epitopes which (under natural conditions) are relatively less antigenic. The immune dampened and refocused P2 and P5 will be tested singly and in combination for their ability to induce cross strain protective antibody. Immune dampening technology provides for a new approach to circumventing the issues of antigenic variation and could help into the creation of more broadly protective vaccines against a variety of bacterial, viral and parasitic diseases of man and animals.