Analysis of Viral Resistance in CMV Retinitis

描述（由申请人提供）：本申请用于分析巨细胞病毒（CMV）视网膜炎和病毒耐药性（CRVR）研究产生的数据。巨细胞病毒性视网膜炎是艾滋病患者常见的机会性感染。未经治疗的巨细胞病毒性视网膜炎是一种进行性感染，其最终结果是视网膜的破坏和失明。除非高活性抗逆转录病毒治疗（HAART）导致免疫重建，否则需要进行慢性抑制治疗以防止疾病复发。耐药巨细胞病毒（由于UL97或UL54基因的突变）据报道，在抗巨细胞病毒治疗9个月后，约25%的患者发生耐药性巨细胞病毒。血液或尿液中的耐药巨细胞病毒与视网膜炎进展、视网膜面积丧失和视力丧失的风险显著增加相关。在眼睛中检测到的巨细胞病毒基因组几乎总是与在血液或尿液中检测到的基因组相同。许多视网膜炎的复发是由于眼内药物渗透有限，而不是由于耐药性，目前的做法通常是用相同的药物重新诱导患者，而不是转换药物，这种方法对耐药巨细胞病毒无效。如果发现耐药巨细胞病毒，则改用替代药物治疗。目前用于识别携带耐药巨细胞病毒的患者的方法需要培养和检测分离株的耐药性，这一过程可能需要10周。为了使耐药检测获得临床应用，需要更快速的方法来识别携带耐药巨细胞病毒的患者；两种候选方法是：1)巨细胞病毒载量；2)聚合酶链反应（PCR）扩增血液标本中的巨细胞病毒DNA，并对其进行测序，以寻找赋予更昔洛韦耐药性的突变。CRVR研究是一项对309例艾滋病合并巨细胞病毒视网膜炎患者进行的前瞻性研究，研究从血液或尿液中分离出的耐药巨细胞病毒的发生情况。我们将利用CRVR研究产生的数据：1)评估巨细胞病毒载量，作为快速识别耐药巨细胞病毒患者的一种手段；2)评估血液标本中CMV UL97基因的PCR和测序，作为快速识别对更昔洛韦耐药的CMV患者的手段；3)评价HAART对耐药巨细胞病毒发生率的影响。我们的假设是：1)CMV病毒载量的增加将是耐药CMV患者的标志；2)直接血液筛查CMV UL97突变将识别携带更昔洛韦耐药CMV的患者；3)在发生巨细胞病毒性视网膜炎并开始HAART治疗的患者中，耐药率会下降，但在已经接受HAART治疗后发生巨细胞病毒性视网膜炎的患者中，耐药率与HAART前的耐药率相似。计划发表三篇论文：1)《巨细胞病毒载量作为巨细胞病毒性视网膜炎患者耐药巨细胞病毒的预测因子》；2)“血液标本UL97基因PCR扩增及测序鉴定CMV视网膜炎患者耐药CMV”；3)“HAART治疗对巨细胞病毒性视网膜炎患者耐药巨细胞病毒发生率的影响。”

DESCRIPTION (provided by applicant): This application is for analyses of data generated by the Cytomegalovirus (CMV) Retinitis and Viral Resistance (CRVR) Study. CMV retinitis is a common opportunistic infection among patients with AIDS. Untreated CMV retinitis is a progressive infection, the end result of which is destruction of the retina and blindness. Unless immune reconstitution occurs as a consequence of highly active antiretroviral therapy (HAART), chronic, suppressive therapy is required to prevent relapse of the disease. Resistant CMV (due to mutations in the UL97 or UL54 genes) has been reported to occur in approximately25% of patients by 9 months of anti-CMV therapy. Resistant CMV in the blood or urine is associated with substantially increased risks of retinitis progression, loss of retinal area, and loss of visual acuity. The genome of CMV detected in the eye is nearly always identical to that detected in the blood or urine. Many relapses of retinitis are due to limited intraocular drug penetration rather than resistance, and current practice typically is to re-induce patients with the same drug rather than switch drugs, an approach which is ineffective for resistant CMV. If resistant CMV is identified, treatment is changed to an alternative drug. Current methods for identifying patients who harbor resistant CMV require culturing and testing isolates for resistance, a process which may take 10 weeks. In order for resistance testing to achieve clinical utility, more rapid methods for identifying patients who harbor resistant CMV are needed; two candidates are: 1) CMV viral load, and 2) polymerase chain reaction (PCR) amplification of CMV DNA from blood specimens and sequencing it for mutations conferring ganciclovir resistance. The CRVR Study is a prospective study of 309 patients with AIDS and CMV retinitis for the occurrence of resistant CMV isolated from either the blood or urine. We will use data generated from the CRVR Study to: 1) evaluate CMV viral load as a means to rapidly identify patients who harbor resistant CMV; 2) evaluate PCR and sequencing of the CMV UL97 gene from blood specimens as a means to rapidly identify patients who harbor CMV resistant to ganciclovir; and 3) to evaluate the effect of HAART on the incidence of resistant CMV. Our hypotheses are that: 1) increases in CMV viral load will be a marker for patients who harbor resistant CMV; 2) screening of blood directly for CMV UL97 mutations will identify patients who harbor ganciclovir-resistant CMV; and 3) that the rate of resistance will be decreased among patients who developed CMV retinitis and then were started on HAART but similar to that from the pre-HAART era among patients who develop CMV retinitis after already having been treated with HAART. Three publications are planned: 1) "CMV viral load as a predictor of resistant CMV among patients with CMV retinitis"; 2) "PCR amplification and sequencing of the UL97 gene from blood specimens to identify resistant CMV among patients with CMV retinitis"; and 3) "The effect of HAART on the incidence of resistant CMV among patients with CMV retinitis."