Immunomodulatory Function of Human T Cell Leukemia Virus Type 2 (HTLV-2)

描述(由申请人提供) 人类T白血病病毒1型(HTLV-1)及其基因副本HTLV-2是首次描述的人类逆转录病毒。与人类免疫缺陷病毒(HIV-1)不同，HTLV-1和HTLV-2的感染通常是沉默的，在个人的整个一生中都没有症状。HIV-1与HTLV-1和HTLV-2之间的不同病理很可能是由于调节病毒复制、潜伏和宿主细胞内运输的病毒附属基因的不同。在HTLV-1和HTLV-2中，转录激活蛋白Tax1和Tax2是病毒复制所必需的，但也是通过CREB和NF：B途径的细胞启动子。HTLV-1Tax1蛋白的体外活性已被广泛评估，特别是在其作为癌蛋白功能的背景下。Tax2似乎缺乏这种能力，这可能是HTLV-2致病性低的部分原因。此外，Tax2还被报道对CREB和NF：B的反式激活很差。然而，我们实验室进行的初步实验表明，在大肠杆菌(或稳定转导的Jurkat细胞)中表达的Tax2蛋白是外周血单核细胞(PBMC)产生β趋化因子的有效诱导剂，并被观察到下调CCR5共同受体的表达，提高PBMC的活性和淋巴增殖能力。此外，Tax2还能抑制HIV-1感染的PBMC和淋巴样细胞中HIV-1p24抗原的释放。假设：HTLV-2及其调控基因产物Tax2通过增加淋巴细胞活性和增殖，诱导β趋化因子，下调CC趋化因子受体，具有改变固有宿主免疫反应的潜力。由此产生的影响可能会改变宿主在与包括HIV-1在内的其他病原体共同感染时的反应。目的：(1)比较野生型HTLV-2(wtHTLV-2)和Tax2缺陷型HTLV-2感染性克隆(TaxHTLV-2)对PBMC增殖能力和β-趋化因子分泌的影响，以证实和验证Tax2的体外功能。作为一个子目标，将比较CD4+T细胞亚群和CD8+T细胞亚群中β趋化因子的相对表达水平。(2)通过比较重组Tax2蛋白和一组Tax2突变体诱导抗病毒趋化因子的能力，探讨Tax2诱导抗病毒趋化因子的机制。突变蛋白将包括核因子-KB激活区、CREB结合区和核定位区的变化。(3)探讨HTLV-2Tax2蛋白在HIV-1/HTLV-2混合感染过程中作为免疫调节剂的可能优势作用。这项研究的总体目标是了解Tax2在HTLV-2感染者中调节淋巴细胞功能的作用，并揭示其在HIV-1/HTLV-2混合感染患者中改变HIV-1感染的作用。该项目探索了一种新的方法来检测一种病毒(HTLV-2)的辅助蛋白改变宿主细胞库中第二种相关病毒(HIV-1)的生物生命周期的可能性。我们预计，拟议的研究将促进我们对逆转录病毒感染动态的了解，逆转录病毒感染影响着全国数千名退伍军人。 公共卫生相关性： 拟议研究与退伍军人健康和/或医疗保健问题的相关性：艾滋病毒流行对退伍军人医疗保健系统[http://www.hiv.va.gov/vahiv?page=prin-data-2005].产生了重大影响自1998年以来，退伍军人管理局通过免疫病例登记处(ICR)追踪向艾滋病毒患者提供的护理。ICR的数据来自退伍军人事务部的电子病历系统，其中包括关于临床情况和医疗保健利用的广泛信息。2005财政年度期间，估计有26000名感染艾滋病毒的退伍军人在退伍军人管理局登记接受治疗。由于担心毒性，许多感染艾滋病毒的退伍军人不愿坚持HAART疗法。出于这些原因，对于艾滋病毒感染者来说，与较低的毒性和治疗失败率相关的任何新的治疗策略都是至关重要的。拟议的研究将集中于探索艾滋病毒感染患者基于免疫的治疗的可能策略。

DESCRIPTION (provided by applicant) The human T leukemia virus type 1 (HTLV-1) and its genetic counterpart, HTLV-2, are the first-described human retroviruses. Unlike human immunodeficiency virus (HIV-1), infections with HTLV-1 and HTLV-2 are generally silent and asymptomatic for the entire lifetime of an individual. The differential pathology seen between HIV-1 and HTLV-1 and HTLV-2 is most likely attributable to differences in viral accessory genes regulating viral replication, latency, and transport within the host cell. In the case of HTLV-1 and HTLV-2, the transcriptional activating proteins, known as Tax1 and Tax2, are essential for viral replication, but are also cellular promoters via the CREB and NF:B pathways. The in vitro activity of the HTLV-1 Tax1 protein has been evaluated extensively, especially in the context of its ability to function as an oncoprotein. Tax2 seems to lack this ability, which may account in part for the low pathogenecity of HTLV-2. Tax2 has additionally been reported to exhibit poor transactivation of both CREB and NF:B. Nonetheless, preliminary experiments conducted in our laboratory indicate that Tax2 protein expressed in E. coli (or in stably transduced Jurkat cells) is a potent inducer of beta chemokines by peripheral blood mononuclear cells (PBMCs), and was observed to down-regulate CCR5 co-receptor expression and improve PBMC viability and lymphoproliferative capacity. Additionally, Tax2 was shown to inhibit HIV-1 p24 antigen release in HIV-1 infected PBMCs and lymphoid cells. Hypothesis: HTLV-2 and its regulatory gene product, Tax2, have the potential to modify innate host immune responses though increased lymphocyte viability and proliferation, induction of beta chemokines, and down-regulation of CC-chemokine receptors. The resultant effects could alter host responses during co- infection with other pathogens, including HIV-1. Specific Aims: (1) To confirm and validate the in vitro function of Tax2, wild type HTLV-2 (wtHTLV-2) will be compared with a Tax2-deficient HTLV-2 infectious clone ( TaxHTLV-2) with respect to their ability to affect PBMC proliferative capacity and elaboration of the beta chemokines. As a subaim, relative levels of beta chemokine expression in CD4+ vs. CD8+ T cell subsets will be compared. (2) To determine a mechanism of Tax2-mediated-induction of antiviral chemokines by comparing the ability of a recombinant Tax2 protein with a panel of Tax2 mutants. Mutant proteins will include alterations in the NF-KB activating region, CREB binding region, and nuclear localization region. (3) To implicate a possible dominant role of the HTLV-2 Tax2 protein as a possible immunomodulator during HIV-1/HTLV-2 co- infection. The overall goal of this research is to develop an understanding of the role of Tax2 in modulating lymphocyte function in HTLV-2 infected individuals, and to implicate its role in modifying HIV-1 infection in patients with HIV-1/HTLV-2 co-infections. The project explores a novel approach of examining the potential of an accessory protein of one virus (HTLV-2) to alter the biologic life cycle of a second, related virus (HIV-1) in the host cell reservoirs. We expect that the proposed research will advance our understanding of the dynamics of retroviral infections which affect thousands of Veteran's nationwide. PUBLIC HEALTH RELEVANCE: Relevance of the proposed research to veterans health and/or healthcare issues: The HIV epidemic has had a major impact on the VA healthcare system [http://www.hiv.va.gov/vahiv?page=prin-data-2005]. Since 1998, the VA has tracked the care provided to patients with HIV disease through the Immunology Case Registry (ICR). Data for the ICR are drawn from the VA's electronic medical record system, which includes a broad range of information on clinical condition and health care utilization. There were an estimated of 26,000 HIV infected veterans enrolled at VA facilities for treatment during FY2005. Many HIV infected veterans are reluctant to adhere to HAART therapy because of concerns related to toxicity. For these reasons, any new strategies for therapy associated with lower rates of toxicity and treatment failure are critically needed for HIV infected individuals. The proposed studies will focus on exploring possible strategies for immune based therapy of HIV infected patients.