Babady N Esther, Cheng Cindy, Cumberbatch Evelyn, Stiles Jeffrey, Papanicolaou Genovefa, Tang Yi-Wei
Department of Laboratory Medicine, Microbiology Service, Memorial Sloan-Kettering Cancer Center, New York, New York, USA
Department of Laboratory Medicine, Microbiology Service, Memorial Sloan-Kettering Cancer Center, New York, New York, USA.
J Clin Microbiol. 2015 Apr;53(4):1252-7. doi: 10.1128/JCM.03435-14. Epub 2015 Feb 4.
Cytomegalovirus (CMV) viral loads in hematopoietic stem cell transplant (HSCT) recipients are typically monitored using quantitative molecular assays. The Roche Cobas AmpliPrep/Cobas TaqMan CMV test (Cobas CMV) has recently been cleared by the FDA for the monitoring of CMV viral loads in plasma samples from transplant patients. In this study, we compare and correlate the viral loads obtained by a laboratory-developed test (LC CMV) (using Roche analyte-specific reagents [ASR] on the LightCycler 2.0) on whole-blood specimens with those obtained on corresponding plasma and whole-blood specimens by the Cobas CMV assay. Testing was performed on 773 archived patient specimens. The strength of the agreement was good for the two assays performed on whole blood (κ=0.6; 95% confidence interval [CI], 0.51 to 0.7) and moderate when the tests were performed on different sample types (κ=0.54; 95% CI, 0.47 to 0.62 for the LC CMV whole blood [WB] assay versus Cobas plasma [PL], and κ=0.57; 95% CI, 0.5 to 0.65 for the Cobas WB assay versus Cobas PL), although the difference was not statistically significant. Using a combination gold standard (i.e., a true positive was a specimen that was positive by two or more methods), the sensitivity and specificity of the assays were 78.8% and 99.3% for the LC CMV assay, 85.2% and 98.1% for the Cobas CMV WB assay, and 100% and 90.5% for Cobas CMV PL assay, respectively. A comparison of the CMV viral load trends in both plasma and whole blood from a few patients with multiple positive successive samples showed similar slopes, with differences in the slope ranging from 0.01 to 0.22. However, the absolute value for individual viral load differed markedly with whole-blood viral loads, being on average 0.5- to 1.22-log higher than those in plasma. The Cobas CMV assay provides a valid option for the monitoring of viral loads in transplant patients. Due to its increased sensitivity, the detection of CMV DNA in patients with low viral loads (i.e., those below limit of quantification [LOQ]) is increased with the Cobas CMV assay in plasma specimens. Longitudinal prospective studies will be needed to examine the clinical significance of these low-level viral loads.
造血干细胞移植（HSCT）受者的巨细胞病毒（CMV）病毒载量通常采用定量分子检测法进行监测。罗氏Cobas AmpliPrep/Cobas TaqMan CMV检测（Cobas CMV）最近已获美国食品药品监督管理局（FDA）批准，用于监测移植患者血浆样本中的CMV病毒载量。在本研究中，我们将实验室自行开发的检测方法（LC CMV）（在LightCycler 2.0上使用罗氏分析物特异性试剂[ASR]）对全血标本检测获得的病毒载量，与通过Cobas CMV检测法对相应血浆和全血标本检测获得的病毒载量进行比较并关联分析。对773份存档患者标本进行了检测。两种全血检测方法的一致性强度良好（κ=0.6；95%置信区间[CI]，0.51至0.7），而当对不同样本类型进行检测时一致性为中等（LC CMV全血[WB]检测法与Cobas血浆[PL]检测法相比，κ=0.54；95%CI，0.47至0.62；Cobas WB检测法与Cobas PL检测法相比，κ=0.57；95%CI，0.5至0.65），尽管差异无统计学意义。采用联合金标准（即一个真正的阳性样本是通过两种或更多方法检测为阳性的标本），LC CMV检测法的灵敏度和特异性分别为78.8%和99.3%，Cobas CMV WB检测法为85.2%和98.1%，Cobas CMV PL检测法为100%和90.5%。对少数连续多次检测为阳性的患者的血浆和全血中的CMV病毒载量趋势进行比较，结果显示斜率相似，斜率差异范围为0.01至0.22。然而，个体病毒载量的绝对值在全血病毒载量方面有显著差异，平均比血浆中的病毒载量高0.5至1.22个对数。Cobas CMV检测法为监测移植患者的病毒载量提供了一个有效的选择。由于其灵敏度提高，Cobas CMV检测法在血浆标本中对低病毒载量（即低于定量下限[LOQ]）患者的CMV DNA检测能力增强。需要进行纵向前瞻性研究以检验这些低水平病毒载量的临床意义。
