EIAV Control by High Avidity Rev-Specific CTL Clones

描述（由申请人提供）：在确定慢病毒感染的免疫控制机制方面取得了重大进展，很明显，病毒特异性CTL和CD4+辅助T淋巴细胞在限制慢病毒复制方面至关重要。然而，T淋巴细胞介导的保护的相关因素仍不清楚。具体的知识空白包括如何在面对CD4+ T淋巴细胞缺乏时诱导和支持保护性CTL反应，CTL必须识别的特定表位来控制慢病毒复制，以及保护性CTL的定性特征（即功能贪婪性）。拟议研究的总体目标是描述CD4+ T淋巴细胞缺乏环境中ctl介导的对慢病毒感染的保护要求。正在研究的慢病毒系统是马体内的EIAV。大多数马在一年内控制了EIAV的复制，并持续感染不明显的携带者。感染SCID的阿拉伯马驹感染EIAV的结果，以及EIAV攻击前SCID马驹体内病毒特异性T淋巴细胞和b淋巴细胞的免疫重建，表明这种病毒复制的控制是由病毒特异性免疫反应介导的。由于马SCID缺陷在EIAV引起疾病的宿主物种中自然发生，这个淋巴细胞缺陷模型系统提供了一个机会，以严格的方式剖析慢病毒免疫的相关关系，这在任何其他慢病毒模型系统中都是不可用的。特别是，CD8+ CTL可以转移到SCID马驹中，并在缺乏CD4+ T淋巴细胞的情况下进行评估。本提案中概述的实验将通过外源性IL-2支持的EIAV rev -特异性CTL克隆的过性转移，分析CTL介导的SCID马驹对EIAV的保护的快快度要求。CTL克隆将靶向Rev蛋白的高度保守区域。预计对这种非可变Rev表位特异性的高亲和性CTL克隆将具有保护性，而无需选择逃逸变体。相反，具有相同特异性的低贪婪性CTL克隆的过继转移后，预计不会产生保护作用。完成这些目标将有助于确定CD4+ T淋巴细胞缺乏环境中CTL保护对抗慢病毒攻击的相关因素，包括表位特异性、贪婪性和病毒逃逸。从拟议的研究中获得的信息应该对HIV-1免疫治疗和疫苗设计有影响，这类实验可能更困难。

DESCRIPTION (provided by applicant): Significant progress has been made toward defining the mechanisms of immune control of lentiviral infections, and it is evident that viral specific CTL and CD4+ helper T lymphocytes are critically important in limiting lentiviral replication. However, correlates of T lymphocyte-mediated protection are still not known. Specific knowledge gaps include how to induce and support a protective CTL response in the face of CD4+ T lymphocyte deficiency, the specific epitopes that must be recognized by CTL to control lentivirus replication, and the qualitative characteristics (i.e. functional avidity) of protective CTL. The overall goal of the proposed research is to delineate the requirements of CTL-mediated protection against lentiviral infection in a CD4+ T lymphocyte deficient environment. The lentiviral system under study is EIAV in horses. Most horses control EIAV replication within a year and remain persistently infected unapparent carriers. Results of EIAV infection in Arabian foals affected with SCID, as well as immune reconstitution with viral-specific T and B-lymphocytes in a SCID foal prior to EIAV challenge, indicate that this control of viral replication is mediated by a viral-specific immune response. Since the equine SCID defect occurs naturally in the host species in which EIAV causes disease, this lymphocyte deficient model system provides an opportunity to dissect the correlates of lentiviral immunity in a rigorous way that is unavailable in any other lentiviral model system. In particular, CD8+ CTL can be transferred into SCID foals and evaluated in the absence of CD4+ T lymphocytes. The experiments outlined in this proposal will dissect the avidity requirements for CTL-mediated protection against EIAV in SCID foals by adoptive transfer of EIAV Rev-specific CTL clones supported with exogenous IL-2 administration. The CTL clones will target a highly conserved region of the Rev protein. It is anticipated that a high avidity CTL clone specific for this nonvariable Rev epitope will be protective without selecting for escape variants. In contrast, protection is not expected following adoptive transfer of a low avidity CTL clone with the same specificity. Accomplishing these aims should help define the correlates for CTL protection against a lentivirus challenge in a CD4+ T lymphocyte-deficient environment, in terms of epitope specificity, avidity, and viral escape. The information obtained from the proposed studies should have implications for HIV-1 immunotherapy and vaccine design, where experiments of this type may be more difficult.