EIAV Control by High Avidity Rev-Specific CTL Clones

描述（由申请人提供）：在定义慢病毒感染的免疫控制机制方面已经取得了重大进展，很明显，病毒特异性CTL和CD 4+辅助T淋巴细胞在限制慢病毒复制方面至关重要。然而，相关的T淋巴细胞介导的保护仍然是未知的。具体的知识差距包括如何诱导和支持保护性CTL反应，面对CD 4 + T淋巴细胞缺陷，特异性表位，必须识别的CTL控制慢病毒复制，和保护性CTL的定性特征（即功能亲合力）。拟议研究的总体目标是描述在CD 4 + T淋巴细胞缺乏的环境中CTL介导的抗慢病毒感染的保护的要求。正在研究的慢病毒系统是马的EIAV。大多数马在一年内控制EIAV复制，并保持持续感染的隐性携带者。结果EIAV感染的阿拉伯马驹与SCID，以及免疫重建与病毒特异性T和B淋巴细胞的SCID马驹前EIAV的挑战，表明这种控制病毒复制介导的病毒特异性免疫反应。由于马SCID缺陷自然发生在EIAV引起疾病的宿主物种中，因此这种淋巴细胞缺陷模型系统提供了以任何其他慢病毒模型系统中不可用的严格方式剖析慢病毒免疫相关性的机会。特别地，可以将CD 8 + CTL转移到SCID马驹中，并在不存在CD 4 + T淋巴细胞的情况下进行评估。本提案中概述的实验将剖析通过过继转移外源性IL-2给药支持的EIAV Rev特异性CTL克隆，在SCID马驹中CTL介导的抗EIAV保护的亲合力要求。CTL克隆将靶向Rev蛋白的高度保守区域。预期特异于该非可变Rev表位的高亲合力CTL克隆将具有保护性，而不选择逃逸变体。相反，在具有相同特异性的低亲合力CTL克隆的过继转移后，预期不会产生保护作用。实现这些目标应有助于确定相关的CTL保护对慢病毒的挑战，在CD 4 + T淋巴细胞缺陷的环境中，在表位特异性，亲合力，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.