PATHOGENIC DETERMINANTS OF THE SIV ENVELOPE TRANSMEMBRANE CYTOPLASMIC DOMAIN

这个子项目是许多研究子项目中的一个 由NIH/NCRR资助的中心赠款提供的资源。子项目和 研究者（PI）可能从另一个NIH来源获得了主要资金， 因此可在其他CRISP条目中表示。所列机构为 研究中心，而研究中心不一定是研究者所在的机构。 HIV-1建立了一种持续性感染，其特征是在面对强烈的宿主免疫应答、CD 4细胞耗竭和最终AIDS时持续进行病毒复制。对于艾滋病的SIV模型，减毒的SIV为理解发病机制提供了强有力的工具，因为它们是可以被宿主控制的病毒。这些模型还提供了最好的证据，表明宿主免疫反应可以保护动物免受感染和/或疾病时，与致病性分离株的挑战。然而，即使是最佳表征的减毒病毒，其减毒的机制和这种保护的免疫相关性也是未知的。此外，当获得保护时，通常是针对同源病毒而不是异源病毒，这种情况与有效疫苗所需的情况相去甚远。我们的实验室已经表明，SIVmac 239 Env胞质尾中保守的GYxx？运输基序中的突变产生了深度减毒的表型，使这种高致病性病毒对宿主免疫控制敏感。我们还表明，受感染的动物被保护免受同源SIVmac 239攻击的感染，并且显著地，能够控制异源攻击病毒（SIVmac E660）。我们建议扩展我们在这个模型中的初步结果，以表征GYxx？突变对体外病毒的影响，并在恒河猴中进行严格的体内研究，以确定致病性降低和宿主免疫控制的相关性。我们的研究涉及三个目标。 目的#1将评价TM尾突变对病毒体结构、组成、感染性和适应性的影响，并将探索这些病毒中和敏感性增加的基础。目的#2将全面评估粘膜和其他淋巴部位的早期和晚期感染事件，以确定感染的细胞，发生的细胞病变效应，引发的炎症反应，以及在该模型中观察到的减毒是否影响GYxx突变体通过粘膜传播的能力。目标#3将评估对GYxx â突变体的细胞和体液免疫反应，以确定与SIVmac 239相比在广度、特异性和程度上存在哪些差异。将在用致病性异源病毒攻击之前和之后评估应答，以确定保护的免疫相关性。这些目标还将利用已经发展出明显的补偿突变的病毒，因为它们将是未来研究的有力工具，以解决这种减毒和宿主免疫控制模型的基础细胞机制。 到目前为止，已经获得了12只动物，两只已经在早期时间点被感染并安乐死，4只已经感染SIVmac 239 deltanef，其余动物已经通过IV或粘膜途径感染SIVmac 239 deltaGY。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. HIV-1 establishes a persistent infection characterized by ongoing viral replication in the face of vigorous host immune responses, CD4 cell depletion, and ultimately AIDS. For SIV models of AIDS, attenuated SIVs have provided powerful tools to understand pathogenesis, as they are viruses that can be controlled by the host. These models have also provided the best evidence that host immune responses can protect animals from infection and/or disease when challenged with pathogenic isolates. However, for even the best characterized attenuated viruses, the mechanism(s) that underlie their attenuation and the immune correlates of this protection are unknown. Moreover, when protection is achieved, it is typically for homologous rather than heterologous viruses, a scenario far removed from what will be required for an effective vaccine. Our laboratory has shown that mutations in a conserved GYxx¿ trafficking motif in the SIVmac239 Env cytoplasmic tail produce a profoundly attenuated phenotype that renders this highly pathogenic virus susceptible to host immune control. We have also shown that infected animals are protected from infection with a homologous SIVmac239 challenge, and remarkably, are able to control a heterologous challenge virus (SIVmac E660). We propose to extend our preliminary results in this model to characterize the effects of GYxx¿ mutations on the virus in vitro and, in rigorous in vivo studies in rhesus macaques, to identify the correlates of reduced pathogenicity and host immune control. Our studies involve three aims. Aim #1 will evaluate the effects of TM tail mutations on virion structure, composition, infectivity, and fitness, and will explore the basis for the increased neutralization sensitivity of these viruses. Aim #2 will comprehensively evaluate early and late events of infection in mucosal and other lymphoid sites to determine what cells are infected, what cytopathic effects occur, what inflammatory responses are elicited, and whether the attenuation observed in this model affects the ability of GYxx¿ mutants to be transmitted mucosally. Aim #3 will evaluate cellular and humoral immune responses to GYxx¿ mutants to determine what differences exist compared to SIVmac239 in breadth, specificity and magnitude. Responses will be assessed before and after challenge with a pathogenic heterologous virus to determine what are the immune correlates of protection. These aims will also take advantage of viruses that have developed apparent compensatory mutations, as they will be powerful tools for future studies to address basic cellular mechanisms that underlie this model of attenuation and host immune control. To date 12 animals have been acquired, two have been infected and euthanized at early time points, 4 have been infected with SIVmac239deltanef and the remaining animals have been infected with SIVmac239deltaGY by IV or mucosal routes.