Role of immunoglobulin CDR-H3 in heterosubtypic immunity to influenza virus

描述（由申请人提供）：我们寻求更好地了解抗体库作为一个整体在提供对流感病毒的异亚型免疫中的作用。我们发现我们可以根据特定的物理化学性质将抗原结合位点分类。我们已经表明，有些类别在生命的关键阶段是首选的，而其他类别似乎是主动选择的，特别是在年轻人中，他们通常比老年人更能抵抗异亚型感染。初步研究表明，在老年人中可以发现使用“不利”抗原结合位点的免疫球蛋白。由于抗体库控制的一般原理对人类和小鼠似乎是共同的，为了研究库控制在异亚型免疫中的作用，我们创造了抗体库限制在这些高度不受欢迎的类别之一的小鼠。我们之前使用这些小鼠来证明，当携带抗原结合位点属于通常首选类别的抗体完全被使用不受欢迎类别的抗体取代时，对H1N1毒株异亚型攻击的保护受到严重损害。然而，这些研究并没有回答这样一个问题，即是缺乏通常首选的曲目，还是存在属于不受欢迎的类别的序列，从而损害了异亚型免疫。在目前的建议中，我们检验了不利的免疫球蛋白的存在对抗异亚型感染的保护具有主要的负面影响的假设。这是一个关键问题，因为，如上所述，全功能表的组成可以随着年龄或疾病而改变。含有DH位点突变的改变的IgH等位基因的小鼠杂合产生来自正常等位基因的正常库，以及来自基因靶向等位基因的不利抗体。这些小鼠将被用来测试这些不受欢迎的抗体的存在是否足以增加小鼠用H3N2或H1N1毒株免疫后的发病率和死亡率，然后用同源或异源病毒攻击。发病率和死亡率的增加将证实，控制抗体库的整体组成对于对流感病毒作出适当的保护性免疫反应至关重要。随后将测试两种可能导致感染易感性增加的潜在机制。小鼠将被注射血清或骨髓单核细胞，然后用同源或异源病毒攻击。与血清一起给药后发病率的增加将表明可溶性不良抗体的直接作用。只有在细胞转移后发病率才会增加，这表明免疫球蛋白作为B细胞受体的直接作用，可能通过改变抗原对T细胞的递呈。然后，我们将滴度效应，以确定超过阈值，异亚型免疫受损。再加上评估病毒库多样性的新手段，这些信息将用于了解流感病毒感染的易感性，并指导疫苗接种和治疗战略。

DESCRIPTION (provided by applicant): We seek to gain a better understanding of the role of the antibody repertoire as a whole in providing heterosubtypic immunity to influenza virus. We have found that we can group of antigen binding sites into categories defined by specific physical-chemical properties. We have shown that some categories are preferred at key stages of life, whereas others appear to be actively selected against, especially in young adults who typically are more resistant to heterosubtypic infection than aged individuals. Preliminary studies indicate that immunoglobulins using 'disfavored' categories of antigen binding sites can be found in aged individuals. Because the general principles of antibody repertoire control appear common to human and mouse, in order to study the role of repertoire control in heterosubtypic immunity we created mice whose repertoire is limited to one of these highly disfavored categories. We previously used these mice to show that when antibodies bearing antigen binding sites belonging to normally preferred categories were completely replaced by antibodies using a disfavored category, protection against heterosubtypic challenge with an H1N1 strain was severely compromised. However, these studies did not answer the question of whether it was the absence of the normally preferred repertoire or the presence of sequences belonging to a disfavored category that had impaired heterosubtypic immunity. In the present proposal, we test the hypothesis that the presence of disfavored immunoglobulin can have a dominant negative effect on protection against heterosubtypic infection. This is a key issue because, as noted above, the composition of the repertoire can change with age or disease. Mice heterozygous for altered IgH alleles containing mutations in the DH locus produce a normal repertoire from the normal allele, and disfavored antibodies from the gene targeted allele. These mice will be used to test whether the presence of these disfavored antibodies is sufficient to increase morbidity and mortality after mice are immunized with either an H3N2 or an H1N1 strain, and then challenged with homologous or heterologous viruses. The increase in morbidity and mortality will confirm that control of the global composition of the antibody repertoire is essential for properly protective immune responses to influenza virus. Two potential mechanisms that could underlie this increases susceptibility to infection will then be tested. Mice will be injected with sera or infused with bone marrow mononuclear cells from naove or immunized mice, and then challenged with homologous or heterologous viruses. An increase in morbidity after administration with the sera will point to a direct effect of soluble disfavored antibody. An increase in morbidity only after transfer of cells will suggest a direct role of immunoglobulin as a B cell receptor, perhaps by altering antigen presentation to T cells. We will then titer the effect to determine the threshold beyond which heterosubtypic immunity is impaired. Coupled with new means to evaluate repertoire diversity, this information will then be used to inform susceptibility to influenza virus infections and to guide vaccination and treatment strategies. PUBLIC HEALTH RELEVANCE: We seek to understand how the composition of the totality of antibodies produced by the body may affect protection against influenza virus. We plan to use this information both to identify individuals at risk for greater morbidity and mortality, and to guide vaccination and treatment strategies.