Gerna G, Percivalle E, Baldanti F, Sarasini A, Zavattoni M, Furione M, Torsellini M, Revello M G
Servizio di Virologia, IRCCS Policlinico San Matteo, Italy.
New Microbiol. 1998 Jul;21(3):293-308.
In recent years several assays have been developed for quantitation of human cytomegalovirus (HCMV) in blood of immunocompromised (transplanted and AIDS) patients. It is currently agreed that the only reliable indication of the degree of dissemination of HCMV infection/disease is the measurement of HCMV in blood. Diagnosis of HCMV end-organ disease (organ localizations) often does not benefit from quantitation of virus in blood, but requires detection and quantification of virus in samples taken locally. The most important and clinically useful diagnostic assays for HCMV quantitation in blood are: i) viremia, quantifying infectious HCMV carried by peripheral blood leukocytes (PBL); ii) pp65-antigenemia, quantifying the number of PBL positive for HCMV pp65 in the nucleus; iii) circulating cytomegalic endothelial cell (CEC) viremia (CEC-viremia) measuring the number of circulating CEC carrying infectious HCMV (during the antigenemia assay); iv) leuko- and plasma-DNAemia, quantifying the number of HCMV genome equivalents present in PBL or plasma, respectively, by quantitative polymerase chain reaction (Q-PCR). Other less widely used assays are: i) determination of immediate early and late gene transcripts (mRNA) to detect active viral infection; ii) in situ hybridization to detect viral nucleic acid (DNA or RNA) in tissue sections or cell smears; iii) in situ PCR to detect a low DNA copy number in single cells. Monitoring of HCMV infection/disease in transplant recipients and AIDS patients has established threshold values for different assays above which HCMV-related clinical symptoms are likely to appear. These values are approximately 10 for viremia, 100 for antigenemia and 1,000 GE for leukoDNAemia, and are valid for both solid organ and bone marrow transplant recipients as well as AIDS patients, whereas presence of even a single circulating CEC is sufficient to suggest the presence of a disseminated HCMV infection with potential organ involvement. Monitoring of antiviral treatment of HCMV infection/disease with either ganciclovir or foscarnet has aimed at keeping virologic parameters below the threshold values reported above. On the other hand, rising levels of the same virologic parameters during antiviral treatment have mostly revealed emergence of resistant HCMV strains to either ganciclovir (mutations in the UL97 or DNA polymerase gene) or foscarnet (mutations in the UL54 gene) or both drugs (double resistance with both types of mutations). Rapid assays for chemosensitivity testing of virus directly in clinical specimens have been developed to allow timely (4-6 days) detection of resistance to a drug and provide clinicians with the rationale for shifting to an alternative treatment.
近年来，已经开发了几种用于定量免疫功能低下（移植和艾滋病）患者血液中人类巨细胞病毒（HCMV）的检测方法。目前人们一致认为，HCMV感染/疾病传播程度的唯一可靠指标是血液中HCMV的检测。HCMV终末器官疾病（器官定位）的诊断通常无法从血液中病毒定量中获益，而是需要对局部采集的样本进行病毒检测和定量。血液中HCMV定量最重要且临床上有用的诊断检测方法有：i）病毒血症，定量外周血白细胞（PBL）携带的传染性HCMV；ii）pp65抗原血症，定量细胞核中HCMV pp65阳性的PBL数量；iii）循环巨细胞内皮细胞（CEC）病毒血症（CEC - 病毒血症），在抗原血症检测期间测量携带传染性HCMV的循环CEC数量；iv）白细胞和血浆DNA血症，通过定量聚合酶链反应（Q - PCR）分别定量PBL或血浆中存在的HCMV基因组当量数。其他较少广泛使用的检测方法有：i）测定即刻早期和晚期基因转录本（mRNA）以检测活跃的病毒感染；ii）原位杂交以检测组织切片或细胞涂片中的病毒核酸（DNA或RNA）；iii）原位PCR以检测单个细胞中的低DNA拷贝数。对移植受者和艾滋病患者的HCMV感染/疾病监测已经为不同检测方法确定了阈值，高于这些阈值可能会出现HCMV相关的临床症状。这些值对于病毒血症约为10，抗原血症约为100，白细胞DNA血症约为1000 GE，对实体器官和骨髓移植受者以及艾滋病患者均有效，而即使存在单个循环CEC也足以提示存在潜在累及器官的播散性HCMV感染。用更昔洛韦或膦甲酸钠对抗HCMV感染/疾病的治疗监测旨在使病毒学参数保持在上述阈值以下。另一方面，抗病毒治疗期间相同病毒学参数水平的升高大多揭示了对更昔洛韦（UL97或DNA聚合酶基因突变）或膦甲酸钠（UL54基因突变）或两种药物（两种类型突变的双重耐药）耐药的HCMV毒株的出现。已经开发了直接在临床标本中对病毒进行化学敏感性检测的快速检测方法，以便及时（4 - 6天）检测对药物的耐药性，并为临床医生提供转向替代治疗的依据。
