Biochemical Mechanisms of Drug Resistance in HIV-1 RT

描述（由申请人提供）：核苷逆转录酶（RT）抑制剂在HIV-1感染和AIDS的治疗中发挥重要作用;然而，这些药物的长期使用受到耐药突变体选择的限制。这些化合物产生链终止核苷酸，其通过HIV-1 RT掺入并进一步阻断DNA链延伸。该实验室的工作有助于表明HIV-1 RT可以通过转移到核苷酸受体来催化链终止核苷酸的体外切除，并且HIV-1的主要一类核苷抗性突变体编码具有增加的核苷酸依赖性切除活性的RT。本研究拟（a）确定决定体外切除反应效率的因素，包括受体底物的结构特征、链终止残基的结构和引物-模板中的序列元件，（B）研究膦甲酸（PFA）（焦磷酸的结构类似物）抑制切除和DNA合成的机制，并确定PFA抗性突变体对PFA的抗性机制，（c）研究非核苷RT抑制剂对切除和对切除的dNTP抑制的作用，和（d）鉴定确定哪些细胞内化合物作为体内切除的受体底物的因素--即，在未感染和HIV-1感染个体的淋巴细胞中。此外，研究建议扩展这些研究，以确定因素，控制切除在体内使用酶法检测切除的产品。本研究的目的是确定切除活性在HIV-1感染中的作用，这对于开发更有效的抗HIV药物和治疗策略至关重要，特别是针对耐药病毒的出现。

DESCRIPTION (provided by applicant): Nucleoside reverse transcriptase (RT) inhibitors play an important role in therapy for HIV-1 infection and AIDS; however, long-term use of these drugs is limited by the selection of resistant mutants. These compounds give rise to chain-terminating nucleotides that are incorporated by HIV-1 RT and block further DNA chain elongation. Work from this laboratory was instrumental in showing that HIV-1 RT can catalyze the excision in vitro of chain-terminating nucleotides by transfer to a nucleotide acceptor and that a major class of nucleoside resistant mutants of HIV-1 encodes RT with increased nucleotide-dependent excision activity. Research is proposed to (a) define factors that determine the efficiency of the excision reaction in vitro including structural features of the acceptor substrate, structure of the chain-terminating residue, and sequence elements in the primer-template, (b) investigate the mechanism of inhibition of excision and DNA synthesis by foscarnet (PFA), a structural analog of pyrophosphate, and to determine the mechanism of resistance to PFA by PFA-resistant mutants, (c) investigate the effect of non-nucleoside RT inhibitors on excision and on dNTP inhibition of excision, and (d) to identify factors that determine which intracellular compounds serve as acceptor substrates for excision in vivo -- i.e., in lymphocytes from uninfected and HIV-1 infected individuals. In addition, research is proposed to extend these studies to identify factors that control excision in vivo using an enzymatic assay to detect the products of excision. The goal of this research is to define the role of the excision activity in HIV-1 infection, which will be crucial for the development of more effective drugs and therapeutic strategies against HIV, particularly against the emergence of resistant virus.