Critical domains for HIV-1 entry through atypical coreceptor usage

描述（由申请人提供）：绝大多数HIV-1毒株通过与两种辅助受体CCR 5和CXCR 4之一相互作用进入CD 4+靶细胞。已经认为替代性辅助受体不用于原发性临床感染。然而，我们最近发现了一种传播/创始者（T/F）病毒（ZP 6248），其在体外利用多种CD 4+细胞系以及原代人CD 4 + T细胞和巨噬细胞上的CCR 5和CXCR 4共受体的能力严重受损，但在急性感染期间复制到高血浆病毒载量。与总是使用CCR 5作为辅助受体的所有其他T/F病毒相反，ZP 6248在体外试验中最有效地使用辅助受体GPR 15。ZP 6248罕见的V3冠端中的单一突变（E314 G）恢复了其在CCR 5+细胞中的感染性，但降低了其在GPR 15+细胞中复制的能力。在其他病毒骨架的相同位置引入谷氨酸会导致辅助受体使用的显著改变，但不会使它们在GPR 15+细胞中具有感染性。这是第一例证明HIV-1可以使用CCR 5和CXCR 4以外的辅助受体来建立临床感染的病例。因此，重要的是要了解在不使用CCR 5或CXCR 4作为辅助受体的情况下，在人类中建立原发性HIV-1感染所涉及的机制。此外，令人惊讶的是，V3冠端的单个氨基酸取代导致不同病毒骨架中辅助受体使用的显著改变。这些研究结果提供了一个独特的模型，研究V3冠尖和各种辅助受体之间的精确相互作用。因此，我们将使用这种独特的病毒作为模型来解决以下基本的生物学问题，这些问题对于理解这种进化的病毒病原体的辅助受体向性至关重要：（i）具有非典型辅助受体使用的传播的HIV-1变体使用什么新的感染机制，以及包膜糖蛋白中控制辅助受体向性的基序是什么;（ii）V3冠端中的单个氨基酸取代引起的构象变化如何允许病毒对替代共受体进行采样以建立临床感染。这项工作是我们理解和预测病毒宿主共同进化的核心，这将推动HIV-1流行病的未来。

DESCRIPTION (provided by applicant): The great majority of HIV-1 strains enter CD4+ target cells by interacting with one of two coreceptors, CCR5 and CXCR4. It has been considered that alternative coreceptors are not been used for primary clinical infection. However, we recently discovered a transmitted/founder (T/F) virus (ZP6248) that was profoundly impaired in its ability to utilize CCR5 and CXCR4 coreceptors on multiple CD4+ cell lines as well as primary human CD4+ T cells and macrophages in vitro, yet replicated to a high plasma viral load during acute infection. In contrast to all other T/F viruses that invariably use CCR5 as a coreceptor, ZP6248 uses the coreceptor GPR15 most efficiently in in vitro assays. A single mutation (E314G) in the rare V3 crown tip of ZP6248 restored its infectivity in CCR5+ cells, but reduced its ability to replicate in GPR15+ cells. Introduction of glutamic acid at this same position in other virus backbones leads to significant alterations of coreceptor usage, but does not render them infectious in GPR15+ cells. This is the first case demonstrating that HIV-1 can use coreceptors other than CCR5 and CXCR4 to establish clinical infection. Thus, it will be important to understand what are the mechanisms involved in establishing a primary HIV-1 infection in humans without the use of CCR5 or CXCR4 as coreceptors. In addition, it is striking that a single amino acid substitution at the V3 crown tip leads to significantly altered coreceptor usage in different virus backbones. These findings provide a unique model to study the precise interactions between the V3 crown tip and various coreceptors. Thus, we will use this unique virus as a model to address the following fundamental biological questions that are critical for understanding of coreceptor tropism of this evolving viral pathogen: (i), what novel infection mechanisms are used by a transmitted HIV-1 variant with atypical coreceptor usage and what are the motifs in the envelope glycoprotein that govern the coreceptor tropism; (ii), how conformational changes caused by a single amino acid substitution in the V3 crown tip allows the virus to sample alternative coreceptors to establish clinical infection. This work is central t our understanding and anticipation of virus-host coevolution that will drive the future of the HIV-1 epidemic.