Clinical Virology, Gilead Sciences, Inc, Foster City, CA, USA.
J Acquir Immune Defic Syndr. 2012 Jan 1;59(1):47-54. doi: 10.1097/QAI.0b013e31823aca74.
The registrational phase III clinical trials of the nonnucleoside reverse transcriptase (RT) inhibitor (NNRTI) rilpivirine (RPV) in combination with two nucleoside/nucleotide RT inhibitors (NRTIs) found a unique genotypic resistance pattern involving the NNRTI mutation E138K with the NRTI mutation M184I. Eighty percent of subjects used emtricitabine (FTC) and tenofovir disoproxil fumarate (TDF); a single tablet regimen of FTC/RPV/TDF is in development.
HIV-1 with E138K and/or M184V or I mutations were constructed and phenotyped in MT-2 cells and the PhenoSense and Antivirogram assays. Viral fitness was determined using growth competitions. Molecular models of the mutants were constructed from the RT-RPV crystal structure.
The E138K mutant showed low-level reduced susceptibility to RPV (2.4-fold), but full susceptibility to FTC and tenofovir (TFV). Viruses with M184V or M184I showed high-level resistance to FTC and full susceptibility to RPV and TFV. Addition of M184I, but not M184V, to E138K, further decreased susceptibility to RPV and maintained FTC resistance. The E138K and M184V or I single and double mutants showed decreased replication fitness compared with wild type. M184V outcompeted M184I when compared directly and in the background of E138K. E138K + M184I was less fit than either E138K or M184I alone. Removing a salt bridge between E138/K101 is implicated in resistance to RPV.
The higher frequency of E138K and M184I among RPV + FTC/TDF virologic failures is due to reduced susceptibility of the single mutants to RPV and FTC and the enhanced resistance to RPV for the double mutant at the cost of decreased viral fitness.
非核苷类逆转录酶抑制剂（NNRTI）利匹韦林（RPV）与两种核苷/核苷酸逆转录酶抑制剂（NRTIs）联合进行的注册 3 期临床试验发现了一种独特的基因型耐药模式，涉及 NNRTI 突变 E138K 和 NRTI 突变 M184I。80%的受试者使用恩曲他滨（FTC）和替诺福韦富马酸酯（TDF）；正在开发一种含 FTC/RPV/TDF 的单片方案。
构建并表型分析了含有 E138K 和/或 M184V 或 I 突变的 HIV-1 ，并在 MT-2 细胞中和 PhenoSense 和 Antivirogram 测定中进行了表型分析。使用生长竞争来确定病毒适应性。从 RT-RPV 晶体结构构建了突变体的分子模型。
E138K 突变体对 RPV 的敏感性降低了 2.4 倍，但对 FTC 和替诺福韦（TFV）的敏感性完全保留。含有 M184V 或 M184I 的病毒对 FTC 具有高度耐药性，对 RPV 和 TFV 的敏感性完全保留。E138K 中加入 M184I，但不是 M184V，会进一步降低对 RPV 的敏感性，并保持 FTC 耐药性。与野生型相比，E138K 和 M184V 或 I 的单突变体和双突变体的复制适应性降低。直接比较时，M184V 比 M184I 更具竞争力，在 E138K 背景下也是如此。E138K+M184I 的适应性比 E138K 或 M184I 单独存在时更差。在 E138/K101 之间形成盐桥的缺失与对 RPV 的耐药性有关。
在 RPV+FTC/TDF 病毒学失败中 E138K 和 M184I 的频率较高，是因为单突变体对 RPV 和 FTC 的敏感性降低，双突变体对 RPV 的耐药性增强，以牺牲病毒适应性为代价。
