Prevention of AIDS

预防艾滋病

• 批准号: 7338497
• 负责人: BARBARA K FELBER
• 金额: --
• 依托单位: DIVISION OF BASIC SCIENCES - NCI
• 依托单位国家: 美国
• 资助国家: 美国
• 起止时间: 至
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/7338497
• 关键词: Prevention; AIDS

To study prevention of AIDS, we have a long-standing collaboration with George Pavlakis (Human Retrovirus Section, Vaccine Branch), and we have generated efficient DNA expression vectors, which are currently evaluated as vaccines against SIV and HIV. This work is based on the previous recognition that RNA elements (called INS) present within the gag/pol and env coding regions of HIV are responsible for nuclear retention and instability of the transcripts in the absence of Rev, and that these elements can be eliminated by changing the RNA composition without affecting the amino acid sequence. These RNA optimized gag and env expression vectors mediate the development of protective immune responses in vaccinated macaques when used as DNA only as well as DNA prime vaccine modality. We have now shown that that a combination of DNA vaccine vectors producing native and modified antigens are able to induce immune responses able to protect from high viremia in the rhesus macaque/SIVmac251 model. Current studies examine the role of these DNA vaccines as therapeutic modalities. In collaboration with other investigators we have studied immunogenicity of additional HIV and SIV genes either as DNAs or as part of viral vectors. We have shown that these DNAs provide an excellent prime in DNA prime-recombinant Herpes boost studies inducing protective immune responses. We have also shown that combinations of SIV DNA vaccine together with IL-12 or IL-15 as DNA adjuvants improve immunogenicity.Our goal is to dissect correlates of protective immunity, which will allow design of better vaccine strategies. Thus infected macaques, able to control viremia serve as model to study the underlying mechanisms. Among the 'controllers', animals infected with live-attenuated SIV strains provide an important model to study cellular and viral determinants that contribute to disease development and they also provide a unique tool to study mechanisms leading to protective immunity. We study the regulated expression of HIV, which is mediated via the viral Rev protein with the goal to evaluate the role of Rev in pathogenesis. Our discovery of other RNA export mechanisms (mediate via cellular RNA export factors and retrovial RNA export elements CTE, RTE as studied in project 1) provided the key tools to generate HIV and SIV variants that have the Rev/RRE regulatory system replaced. CTE or RTE provide us also with useful tools to achieve efficient expression of HIV and SIV structural protein in simple DNA vectors used as vaccine approaches against AIDS. Importantly, we found that our Rev-independent SIV strains are not pathogenic in rhesus macaques, which demonstrates that the Rev regulation plays an important role for SIV pathogenicity. In a recent long-term follow-up study we showed that such animals show persistent humoral and cellular SIV-specific immune responses, consistent with chronic infection but lack of pathogenicity. Multicolor flow cytometric analysis demonstrated preservation of the Central Memory subset of T-cells in the attenuated SIV-infected animals. This study demonstrates a potent, long-lasting control of the Rev-independent attenuated SIV in macaques. Replacement of the natural regulatory controls of Rev-RRE by the CTE provides a novel approach to lower the virulence of a pathogenic lentivirus. These studies provide critical information about the establishment and maintenance of host immune responses during chronic retroviral infections with distinct pathogenic outcomes. Macaques immunized with attenuated viruses develop persistent humoral and cellular immune responses, able to protect the animals from highly pathogenic SIV challenge. We are in the process to study the underlying mechanism. Therefore, these live-attenuated SIV strains provide us not only with a unique tool to dissect cellular and viral determinants that contribute to AIDS development, but are also useful for studying correlates of protective immunity.

为了研究艾滋病的预防，我们与George Pavlakis（人类逆转录病毒科、疫苗分部）进行了长期合作，并生成了高效的DNA表达载体，目前正在评估其作为针对SIV和HIV的疫苗。这项工作基于之前的认识，即 HIV 的 gag/pol 和 env 编码区中存在的 RNA 元件（称为 INS）负责在没有 Rev 的情况下转录物的核保留和稳定性，并且可以通过改变 RNA 组成来消除这些元件，而不影响氨基酸序列。这些 RNA 优化的 gag 和 env 表达载体在仅用作 DNA 以及 DNA 初免疫苗形式时，可介导已接种疫苗的猕猴中保护性免疫反应的发展。我们现在已经证明，产生天然抗原和修饰抗原的 DNA 疫苗载体的组合能够诱导免疫反应，从而能够在恒河猴/SIVmac251 模型中预防高病毒血症。目前的研究探讨了这些 DNA 疫苗作为治疗方式的作用。我们与其他研究人员合作，研究了其他 HIV 和 SIV 基因作为 DNA 或作为病毒载体的一部分的免疫原性。我们已经证明，这些 DNA 在 DNA 引发剂重组疱疹增强研究中提供了出色的引发剂，可诱导保护性免疫反应。我们还表明，SIV DNA 疫苗与作为 DNA 佐剂的 IL-12 或 IL-15 的组合可提高免疫原性。我们的目标是剖析保护性免疫的相关性，这将有助于设计更好的疫苗策略。因此，能够控制病毒血症的受感染猕猴可以作为研究潜在机制的模型。在“控制者”中，感染减毒活毒株的动物为研究导致疾病发展的细胞和病毒决定因素提供了重要的模型，并且还为研究导致保护性免疫的机制提供了独特的工具。我们研究了 HIV 的调节表达，这是通过病毒 Rev 蛋白介导的，目的是评估 Rev 在发病机制中的作用。我们对其他 RNA 输出机制的发现（通过细胞 RNA 输出因子和逆转录 RNA 输出元件 CTE、RTE 介导，如项目 1 中研究的）提供了生成 HIV 和 SIV 变体的关键工具，这些变体已取代 Rev/RRE 调节系统。 CTE 或 RTE 还为我们提供了有用的工具，以在用作艾滋病疫苗方法的简单 DNA 载体中实现 HIV 和 SIV 结构蛋白的有效表达。重要的是，我们发现Rev独立的SIV毒株在恒河猴中不具有致病性，这表明Rev调节对于SIV致病性起着重要作用。在最近的一项长期随访研究中，我们表明这些动物表现出持续的体液和细胞 SIV 特异性免疫反应，与慢性感染一致，但缺乏致病性。多色流式细胞术分析表明，SIV 减毒感染动物中 T 细胞中央记忆子集的保存。这项研究证明了对猕猴中 Rev 独立的减毒 SIV 的有效、持久的控制。 CTE 取代 Rev-RRE 的自然调控控制提供了一种降低致病性慢病毒毒力的新方法。这些研究提供了有关在具有不同致病结果的慢性逆转录病毒感染期间宿主免疫反应的建立和维持的关键信息。用减毒病毒免疫的猕猴会产生持久的体液和细胞免疫反应，能够保护动物免受高致病性 SIV 的攻击。我们正在研究其潜在机制。因此，这些减毒活的SIV毒株不仅为我们提供了一种独特的工具来剖析有助于艾滋病发展的细胞和病毒决定因素，而且对于研究保护性免疫的相关性也很有用。