Cytomegalovirus: Quantitative Polymerase Chain Reaction

巨细胞病毒（CMV）疾病是一种相对常见的，往往是严重的，在免疫功能低下，CMV感染的患者并发症。在过去的几年中，很明显，要区分亚临床病毒脱落和大规模病毒复制，发生在活动性疾病发作前的前驱症状期间，有必要使用定量检测进行连续监测。几项研究表明，CMV定量聚合酶链反应（PCR）检测比血沉棕黄层CMV抗原检测更敏感。在某些情况下，这种额外的敏感性可以在CMV疾病发作前提供额外的一周警告。在前驱期较早的时间点进行抗病毒治疗可能会降低患者发生活动性CMV疾病的机会。我们已经完成了一个竞争性定量PCR检测血沉棕黄层细胞中CMV的发展。该检测试剂盒可以在扩增反应管中检测到少至三至五个病毒基因组当量。该测定的变异系数约为40%，与其他已发表的此类测定的描述一致。为了使检测方法具有更高的精确度，从而更好地预测疾病的发生或进展，我们开发了一种实时CMV PCR检测方法。该检测采用频率共振能量转移荧光探针，设计在Roche LightCycler上运行。该检测试剂盒的扩增和检测可在45至50分钟内完成。除了继续实时PCR检测的开发工作外，我们还开始对Organon Teknika NASBA pp67 CMV检测进行评价。该市售检测试剂盒使用逆转录酶和RNA聚合酶在等温反应中扩增CMV RNA。进行了一项回顾性研究，比较了真实的实时定量CMV PCR检测试剂盒与NASBA pp67和pp65抗原检测试剂盒的性能。发现实时CMV PCR检测可检测由pp65抗原检测鉴定的所有CMV病毒血症的显著发作，但在约75%的发作中至少提前一周给出阳性信号。pp67 NASBA测定的灵敏度低于其他两种方法。这些结果在2001年5月的美国微生物学会会议上发表。我们已经启动了一项前瞻性研究，利用实时CMV PCR检测骨髓移植患者的全血样本。

Cytomegalovirus (CMV) disease is a relatively frequent, and often serious, complication in immunocompromised, CMV-infected patients. In the past few years, it has become apparent that to differentiate between subclinical viral shedding and large-scale viral replication, occurring during the prodrome before the onset of active disease, it is necessary to use sequential monitoring with a quantitative assay. Several studies have shown that CMV quantitative polymerase chain reaction (PCR) assays are more sensitive than buffy coat CMV antigen detection assays. This extra sensitivity can, in some cases, give an additional week of warning before the onset of CMV disease. Instituting antiviral therapy at an earlier time point in the prodromal stage may decrease the chance of the patient developing active CMV disease. We have completed development of a competitive quantitative PCR assay for the detection of CMV in buffy coat cells. The assay can detect as few as three to five viral genome equivalents in an amplification reaction tube. The coefficient of variance of this assay is about 40 percent, in line with other published descriptions of assays of this type. To have an assay with improved precision and, therefore, better potential predictive value for disease onset or progression, we have developed a real-time CMV PCR assay. This assay utilizes frequency resonance energy transfer fluorescence probes and is designed to run on the Roche LightCycler. Amplification and detection of the assay can be completed within 45 to 50 minutes. In addition to continuing the developmental work on a real-time PCR assay, we have begun performing an evaluation of the Organon Teknika NASBA pp67 CMV assay. This commercially available assay amplifies CMV RNA in an isothermal reaction using reverse transcriptase and RNA polymerase. A retrospective study was conducted comparing the performance of the real time quantatitive CMV PCR assay with the NASBA pp67 and pp65 antigen detection assays. The real-time CMV PCR assay was found to detect all the significant episodes of CMV viremia identified by the pp65 antigen assay, but also gave a positive signal at least a week earlier in about 75% of the episodes. The pp67 NASBA assay was less sensitive than the other two methods. These results were presented at the American Society for Microbiology meeting in May, 2001. We have initiated a prospective study utilizing the real-time CMV PCR assay to test whole blood samples from bone marrow transplant patients.