Protective role of V2 antibodies induced at mucosal tissues in macaques

 描述（由申请人提供）：抗体（Ab）在预防HIV-1感染中的作用已通过在几种动物模型中进行的大量被动免疫实验牢固确立。然而，开发一种有效的HIV疫苗诱导保护性抗体是现代医学的一个重大挑战。除了RV 144疫苗试验之外，过去的努力取得了令人失望的结果。在RV 144疫苗的接受者中，高水平的血浆抗V2抗体与HIV-1感染风险降低呈负相关。然而，V2抗体是否直接保护免受感染或V2抗体是否与疫苗功效相关仍然未知。为了解决这些问题，在非人类灵长类动物中进行实验是必要的，因为这种模型具有与人类最相似的免疫反应。因此，我们建议研究抗V2单克隆抗体（mAb）的各种抑制功能和疫苗诱导的恒河猴粘膜抗V2 Ab的机制作用，即，这些抗体是否单独或与其它抗HIV-1包膜（Env）抗体协同保护抵抗SHIV攻击。我们假设抗V2抗体抑制gp 120/α4β7整合素相互作用，并阻断HIV-1与表达α4β7、CD 4和CCR 5的Th 17细胞的结合。由于Th 17细胞主要位于粘膜组织中，我们预测抗V2抗体的诱导局部增加粘膜分泌物中V2抗体的滴度，并更有效地阻断病毒与靶T细胞的结合，从而保护免受HIV-1感染。为了验证这一假设，我们将用V1 V2融合蛋白免疫恒河猴，以诱导粘膜和全身抗V2抗体，与gp 120抗体相比，并用SHIV攻击动物，以确定V2抗体的保护潜力。将使用我们实验室在同种型IgG 1和IgG 3中生产的人V2 mAb检测抗V2 Ab的可能抑制功能，包括中和、Fc介导的活性和抑制gp 120/α4β7相互作用（目的1）。这些研究将确定疫苗诱导的粘膜和/或全身性抗V2抗体介导的抑制活性的类型和范围。将使用gp 120 DNA初免和蛋白加强免疫猕猴，包括在粘膜组织处全身给予V1 V2融合蛋白，并与具有CM 244病毒匹配序列的全身gp 120进行比较。目标1中定义的最具代表性的抑制功能将用于监测血清和粘膜分泌物中疫苗诱导的V2 Ab的形成（目标2）。为了确定疫苗效率，将通过多次低剂量的阴道SHIV-BaL接种对在粘膜阴道和直肠分泌物中检测到抗V2 Ab的免疫猕猴进行攻击（目的3）。拟定研究旨在检测抗V2抗体是否具有保护免受SHIV攻击或降低病毒载量的能力，以及粘膜V2抗体是否优于全身V2抗体。本研究的结果将具有实际意义，为HIV疫苗的设计提供信息，以诱导高滴度的全身性抗V2抗体沿着其他抗体，或包括鼻内免疫以诱导粘膜抗V2抗体，以提高疫苗效力。

 DESCRIPTION (provided by applicant): The role of antibodies (Abs) in preventing infection with HIV-1 has been firmly established by a multitude of passive immunization experiments in several animal models. However, developing an effective HIV vaccine inducing protective Abs is a major challenge for modern medicine. Past efforts yielded disappointing results with the exception of the RV144 vaccine trial. In recipients of the RV144 vaccine, high levels of plasma anti-V2 Abs correlate inversely with reduced risk of HIV-1 infection. However, whether the V2 antibodies directly protect against infection or whether the V2 Abs correlate with vaccine efficacy remains unknown. To address these questions, experiments in non-human primates are necessary, since this model has the most similar immune response to humans. Thus, we propose to study the various inhibitory functions of anti-V2 monoclonal Abs (mAbs) and the mechanistic effect of vaccine-induced mucosal anti-V2 Abs in rhesus macaques, i.e., whether these antibodies protect against SHIV challenge alone or in cooperation with other anti-HIV-1 envelope (Env) antibodies. We hypothesize that anti-V2 Abs inhibit the gp120/α4β7 integrin interaction and block binding of HIV-1 to Th17 cells expressing α4β7, CD4 and CCR5. As Th17 cells are mainly located in the mucosal tissues, we predict that induction of anti-V2 Abs locally increases the titer of V2 Abs in mucosal secretions and more efficiently blocks virus binding to target T cells, resulting in protection against HIV-1 infection. To test this hypothesis, we will immunize rhesus macaques with V1V2 fusion protein to induce mucosal and systemic anti-V2 Abs compared to gp120 Abs and challenge the animals with SHIV to determine the protective potentials of V2 Abs. The possible inhibitory functions of anti-V2 Abs, including neutralization, Fc-mediated activities and inhibition the gp120/α4β7 interaction, will be tested using human V2 mAbs produced in our lab in both isotypes IgG1 and IgG3 (Aim 1). These studies will determine the type and range of inhibitory activities mediated by vaccine-induced mucosal and/or systemic anti-V2 Abs. The macaques will be immunized using gp120 DNA prime and protein boost including V1V2-fusion protein administered at mucosal tissues, systemically and compared to systemic gp120 with matching sequence of CM244 virus. The most representative inhibitory functions defined in Aim 1 will be used to monitor the development of vaccine-induced V2 Abs in serum and mucosal secretions (Aim 2). To determine vaccine efficiency, the immunized macaques with detected anti-V2 Abs in mucosal vaginal and rectal secretions will be challenged by multiple low doses of vaginal SHIV-BaL inoculation (Aim 3). The proposed study is designed to test whether anti-V2 antibodies have ability to protect from SHIV challenge or reduce the viral load and whether mucosal V2 antibodies have any advantage over systemic V2 antibodies. The results of this research will have practical consequences to inform the design of HIV vaccine to induce either a high titer of systemic anti-V2 Abs along with other Abs or include intranasal immunization to induce mucosal anti-V2 Abs to increase vaccine efficacy.