Arming Neutrophils for the Destruction of HIV by Anti-HIV Antibody

描述(由申请人提供)：尽管感染后对艾滋病毒有强大的抗体反应，但中和抗体反应很差，在控制疾病方面无效；然而，在非人类灵长类动物模型中，特定抗体已被证明在预防感染方面有效。因此，新的免疫治疗方法对于抗体在治疗艾滋病毒感染中的作用是必要的。除了抗体直接中和病毒外，抗体通过将HIV靶向效应细胞来抑制HIV还有更广泛的潜力。我们假设，使用含有特定抗HIV抗体和抗IgA受体(CD89)抗体的双特异性抗体将HIV导向中性粒细胞，将有效地摧毁HIV和HIV感染的细胞。中性粒细胞是最主要的白细胞类型，在调节细胞细胞毒性方面非常有效，并且相对抵抗艾滋病毒感染。因此，如果它们能够被指导和武装起来摧毁艾滋病毒和受感染的细胞，它们就是对抗感染的重要武器库。基于结构-功能关系，我们建议研究使用三种不同的人类抗HIV单抗产生的双特异性抗体。IgG1b12是一种中和抗体，具有独特的结构，使其更容易接近病毒的CD4结合部位。F425B4e8对V3环也是一种有效的中和抗体，V3环在病毒和感染细胞上相对容易获得。最后，考虑到gp41上保守的簇I表位的暴露，由抗体F240识别，我们也建议确定具有广泛的抗HIV反应性的双特异性抗体摧毁HIV的能力。F240的使用可以清楚地区分固有的中和活性和中性粒细胞的定向杀伤。将测试双特异性抗体刺激中性粒细胞效应器功能和破坏艾滋病毒的能力。双特异性抗体构建物将被制备成单链抗体(ScFv)。然而，由于单链抗体在体内的短半衰期可能是有限的，我们也建议产生带有修改的Fc结构域的构建体。预计部分基于表位暴露，某些构建体将比其他构建体更有效。还将测试构建体对结合了gp120的未感染细胞的旁观者杀伤作用。鉴定在体外有效抑制病毒产生的构建体，并将旁观者杀伤力降至最低，将允许在非人类灵长类感染模型中进行进一步测试。这些研究代表着在治疗慢性艾滋病毒感染方面的重要进展。D 公共卫生相关性：尽管与抗逆转录病毒药物的联合治疗取得了成功，但艾滋病毒感染的治疗还需要其他治疗手段。由于直接抑制病毒的抗体要么在体内无效，要么在体内很少见，我们建议设计针对HIV的抗体来破坏细胞。这些研究代表着在治疗慢性艾滋病毒感染方面的重要进展。

DESCRIPTION (provided by applicant): Despite a robust antibody response to HIV following infection, the neutralizing antibody response is poor and ineffective at controlling disease; however, specific antibodies have been shown effective at preventing infection in non-human primate models. Thus, novel immunotherapeutic approaches are necessary for antibodies to be useful in treating HIV infection. In addition to the direct neutralization of virus by antibodies, there is a broader potential for antibody mediated inhibition of HIV by targeting HIV to effector cells. We hypothesize that directing HIV, using bispecific antibodies incorporating select anti-HIV antibodies and anti-IgA receptor (CD89) antibody, to neutrophils will effectively destroy HIV and HIV infected cells. Neutrophils, which are the most predominant type of white blood cells, are very efficient at mediating cell cytotoxicity as well as relatively resistant to infection with HIV. Therefore, they represent a significant arsenal against infection if they can be directed and armed to destroy HIV and infected cells. Based on structure-function relationships, we propose to study bispecific antibodies generated using three different human anti-HIV monoclonal antibodies. IgG1b12 is a neutralizing antibody with a unique structure giving it improved access to the CD4 binding site of virus. F425B4e8 is also a potent neutralizing antibody, to the V3 loop, which is relatively accessible on virus and infected cells. Finally, given the exposure of the well-conserved cluster I epitope on gp41, recognized by the antibody F240, we also propose to determine the ability of a bispecific antibody, with broad anti-HIV reactivity, to destroy HIV. The use of F240 allows clear differentiation between inherent neutralization activity from neutrophil directed killing. Bispecific antibodies will be tested for the ability to stimulate neutrophil effector functions and the destruction of HIV. Bispecific antibody constructs will be prepared as single chain Fv (scFv) antibodies. However, since the short half-life of scFv antibodies in vivo may be limiting, we also propose to generate constructs with a modified Fc domain. It is expected that some constructs will be more effective than others based in part on epitope exposure. Constructs will also be tested for bystander killing of uninfected cells with bound gp120. Identification of constructs active in vitro at inhibiting viral production, with minimal bystander killing, will allow for further testing in non-human primate models of infection. These studies represent an important advance in treating chronic HIV infection. D PUBLIC HEALTH RELEVANCE: espite the success of combination therapy with anti-retroviral agents, additional means of therapy are required for the treatment of HIV infection. Since antibodies that directly inhibit virus are either ineffective or rare in vivo, we propose to design antibodies to target HIV to cells for destruction. These studies represent an important advance in treating chronic HIV infection.