White Kirsten L, Margot Nicolas A, Wrin Terri, Petropoulos Christos J, Miller Michael D, Naeger Lisa K
Gilead Sciences, Foster City, California 94404. ViroLogic, Inc., South San Francisco, California 94080, USA.
Antimicrob Agents Chemother. 2002 Nov;46(11):3437-46. doi: 10.1128/AAC.46.11.3437-3446.2002.
Human immunodeficiency virus type 1 (HIV-1) reverse transcriptase (RT) resistance mutations K65R and M184V result in changes in susceptibility to several nucleoside and nucleotide RT inhibitors. K65R-containing viruses showed decreases in susceptibility to tenofovir, didanosine (ddI), abacavir, and (-)-beta-D-dioxolane guanosine (DXG; the active metabolite of amdoxovir) but appeared to be fully susceptible to zidovudine and stavudine in vitro. Viruses containing the K65R and M184V mutations showed further decreases in susceptibility to ddI and abacavir but increased susceptibility to tenofovir compared to the susceptibilities of viruses with the K65R mutation. Enzymatic and viral replication analyses were undertaken to elucidate the mechanisms of altered drug susceptibilities and potential fitness defects for the K65R and K65R+M184V mutants. The relative inhibitory capacities (K(i)/K(m)) of the active metabolites of tenofovir, ddI, and DXG were increased for the RT containing the K65R mutation compared to that for the wild-type RT, but the relative inhibitory capacity of abacavir was only minimally increased. For the mutant viruses with the K65R and M184V mutations, the increase in tenofovir susceptibility compared to that of the mutants with K65R correlated with a decrease in the tenofovir inhibitory capacity that was mediated primarily by an increased K(m) of dATP. The decrease in susceptibility to ddI by mutants with the K65R and M184V mutations correlated with an increase in the inhibitory capacity mediated by an increased K(i). ATP-mediated removal of carbovir as well as small increases in the inhibitory capacity of carbovir appear to contribute to the resistance of mutants with the K65R mutation and the mutants with the K65R and M184V mutations to abacavir. Finally, both the HIV-1 K65R mutant and, more notably, the HIV-1 K65R+M184V double mutant showed reduced replication capacities and reduced RT processivities in vitro, consistent with a potential fitness defect in vivo and the low prevalence of the K65R mutation among isolates from antiretroviral agent-experienced patients.
1型人类免疫缺陷病毒（HIV-1）逆转录酶（RT）耐药性突变K65R和M184V导致对几种核苷类和核苷酸类RT抑制剂的敏感性发生变化。含有K65R的病毒对替诺福韦、去羟肌苷（ddI）、阿巴卡韦和（-）-β-D-二氧戊环鸟苷（DXG；氨多索韦的活性代谢产物）的敏感性降低，但在体外似乎对齐多夫定和司他夫定完全敏感。与含有K65R突变的病毒相比，含有K65R和M184V突变的病毒对ddI和阿巴卡韦的敏感性进一步降低，但对替诺福韦的敏感性增加。进行了酶学和病毒复制分析，以阐明K65R和K65R+M184V突变体药物敏感性改变的机制以及潜在的适应性缺陷。与野生型RT相比，含有K65R突变的RT对替诺福韦、ddI和DXG活性代谢产物的相对抑制能力（K(i)/K(m)）增加，但阿巴卡韦的相对抑制能力仅略有增加。对于含有K65R和M184V突变的突变病毒，与含有K65R的突变体相比，替诺福韦敏感性的增加与替诺福韦抑制能力的降低相关，这主要是由dATP的K(m)增加介导的。含有K65R和M184V突变的突变体对ddI敏感性的降低与由K(i)增加介导的抑制能力的增加相关。ATP介导的卡波韦去除以及卡波韦抑制能力的小幅增加似乎导致了含有K65R突变的突变体以及含有K65R和M184V突变的突变体对阿巴卡韦的耐药性。最后，HIV-1 K65R突变体，更显著的是HIV-1 K65R+M184V双突变体在体外显示出复制能力降低和RT持续合成能力降低，这与体内潜在的适应性缺陷以及抗逆转录病毒药物治疗经验丰富患者分离株中K65R突变的低流行率一致。
