Critical domains for HIV-1 entry through atypical coreceptor usage

描述(由申请人提供)：绝大多数HIV-1毒株通过与两个辅助受体CCR5和CXCR4中的一个相互作用进入CD4靶细胞。已有研究认为，替代辅助受体不能用于原发临床感染。然而，我们最近发现了一种传播型/方正(T/F)病毒(ZP6248)，它在体外利用多个CD4细胞系以及原代人类CD4T细胞和巨噬细胞上的CCR5和CXCR4辅助受体的能力严重受损，但在急性感染时复制到高血浆病毒载量。与所有其他使用CCR5作为辅助受体的T/F病毒不同，ZP6248在体外检测中使用辅助受体GPR15的效率最高。ZP6248罕见的V3冠端的单一突变(E314G)恢复了其在CCR5细胞中的感染性，但降低了其在GPR15细胞中的复制能力。在其他病毒骨架的这个相同位置引入谷氨酸会导致辅助受体使用的显著变化，但不会使它们在GPR15细胞中具有感染性。这是第一例表明HIV-1可以使用CCR5和CXCR4以外的辅助受体来建立临床感染。因此，了解在不使用CCR5或CXCR4作为辅助受体的情况下，在人类中建立原发HIV-1感染的机制将是重要的。此外，令人惊讶的是，V3冠端的单一氨基酸替换导致不同病毒骨架上的辅助受体使用发生显著变化。这些发现为研究V3冠尖和各种辅助受体之间的精确相互作用提供了一个独特的模型。因此，我们将使用这种独特的病毒作为一个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不断演变的病毒病原体的辅受体趋向性至关重要：(I)具有非典型辅受体使用的传播的HIV-1变异体使用什么新的感染机制，以及包膜糖蛋白中控制辅受体趋向性的基序是什么；(Ii)V3冠端的单个氨基酸替换引起的构象变化如何使病毒能够采样替代的辅受体来建立临床感染。这项工作是我们对病毒-宿主共同进化的理解和预期的核心，这将推动艾滋病毒-1流行的未来。

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.