Genetic Pathways of Human Cytomegalovirus Drug Resistance

 描述（由申请方提供）：毒性和耐药性限制了免疫抑制宿主（如癌症和移植受者）巨细胞病毒（CMV）疾病抗病毒治疗的疗效。这项研究的基本目标是描述病毒的特征， 突变和相关机制的抗CMV药物的耐药性在临床上使用，以改善CMV耐药性的基因型诊断和选择和替代疗法的发展。对于目前获得许可的药物（更昔洛韦、膦甲酸和西多福韦），CMV UL 97激酶和UL 54 DNA聚合酶基因中的许多耐药突变和多态性已经并将继续被鉴定和表型分析，有时作为混合亚群。新的抗CMV药物的临床试验最近加速，包括UL 97激酶抑制剂Maribavir，末端酶抑制剂Letermovir，以及其他DNA聚合酶抑制剂Brincidofovir和cyclopropavir。确定这些化合物的耐药性和交叉耐药性的遗传学是这些新的抗病毒治疗选择的一个重要方面。基因分型和重组表型的技术进步促进了这一研究，包括表达用于病毒定量的报告基因的克隆基线实验室菌株的有效诱变、标记蛋白表达系统和下一代测序技术。具体的目标是（1）定义在体外或体内暴露于抗病毒化合物后发生的CMV突变的进化和表型;（2）阐明DNA链延伸的机制，通过该机制，相同的核酸外切酶突变可以赋予对某些聚合酶抑制剂的抗性，但对其他聚合酶抑制剂超敏，和（3）表征对末端酶抑制剂的抗性的遗传途径，重点在于赋予高水平莱特莫韦抗性的UL 56基因区域中的突变。

 DESCRIPTION (provided by applicant): Toxicity and drug resistance limit the efficacy of antiviral therapy for cytomegalovirus (CMV) disease in immunosuppressed hosts such as cancer and transplant recipients. The basic objective of this research is to characterize the viral mutations and associated mechanisms of resistance to anti-CMV drugs in clinical use, in order to improve the genotypic diagnosis of CMV drug resistance and the selection and development of alternate therapies. For currently licensed drugs (ganciclovir, foscarnet and cidofovir), many resistance mutations and polymorphisms in the CMV UL97 kinase and UL54 DNA polymerase genes have been and continue to be identified and phenotyped, sometimes as mixed subpopulations. Clinical trials of new anti-CMV drugs have recently accelerated, including the UL97 kinase inhibitor maribavir, the terminase inhibitor letermovir, and additional DNA polymerase inhibitors brincidofovir and cyclopropavir. Defining the genetics of resistance and cross-resistance among these compounds is an essential aspect of these new antiviral treatment options. Technical advances in genotyping and recombinant phenotyping are facilitating this research, including efficient mutagenesis of cloned baseline laboratory strains expressing reporter genes for viral quantitation, tagged protein expression systems and next-generation sequencing technology. Specific aims are (1) define the evolution and phenotypes of CMV mutations that develop after in vitro or in vivo exposure to antiviral compounds; (2) elucidate mechanisms of DNA chain extension by which the same exonuclease mutations can confer resistance to some polymerase inhibitors but hypersensitivity to others, and (3) characterize the genetic pathways of resistance to terminase inhibitors with emphasis on mutations in a region of the UL56 gene that confer high-level letermovir resistance.