Prince Harry E, Leber Amy L
Focus Technologies, Cypress, California 90630, USA.
Clin Diagn Lab Immunol. 2002 Jul;9(4):824-7. doi: 10.1128/cdli.9.4.824-827.2002.
Measurement of cytomegalovirus (CMV)-specific immunoglobulin G (IgG) avidity has proven to be a powerful tool for distinguishing primary from nonprimary CMV infection. An in-house enzyme-linked immunosorbent assay (ELISA) for measuring CMV IgG avidity was validated using 84 sera from pregnant women who had recently seroconverted following primary CMV infection and 74 sera from individuals with past CMV infection (IgG-positive and IgM-negative profile). Of the 84 sera from pregnant women, 73 sera were collected within 120 days of the last IgG-negative sample, and 72 of these 73 sera (99%) exhibited an avidity index (AI) of <50%. In contrast, 71 of 74 (96%) sera from individuals with past CMV infection exhibited CMV AI values of > 60%. Thus, low avidity in the in-house ELISA was defined as an AI of < or = 50%, whereas high avidity was defined as an AI of > or = 60%. In additional studies, the relationship between CMV IgG avidity and CMV IgM levels was examined using 64 CMV IgG-positive sera (time since seroconversion unknown) exhibiting equivocal or positive results in a CMV IgM capture ELISA (Diamedix). Of these 64 sera, 29 exhibited IgM index values of > or = 3.0, and 27 of these 29 (93%) exhibited low IgG avidity. A similar trend was observed when a subset of these 64 sera (n = 48) was tested in another CMV IgM capture ELISA (Trinity); of 18 sera with IgM index values of > or = 3.0, 17 (94%) exhibited low IgG avidity. These findings demonstrate the validity of an in-house ELISA for CMV IgG avidity and further show that strong reactivity of CMV IgG-positive sera in either of two CMV IgM capture assays is a reliable indicator of low CMV IgG avidity, and thus, recent CMV infection.
巨细胞病毒（CMV）特异性免疫球蛋白G（IgG）亲和力的测定已被证明是区分原发性与非原发性CMV感染的有力工具。使用84份来自原发性CMV感染后近期血清学转换的孕妇血清和74份来自既往有CMV感染（IgG阳性且IgM阴性）个体的血清，对一种用于测量CMV IgG亲和力的内部酶联免疫吸附测定（ELISA）进行了验证。在84份孕妇血清中，73份血清是在最后一份IgG阴性样本后的120天内采集的，这73份血清中的72份（99%）显示亲和力指数（AI）<50%。相比之下，74份既往有CMV感染个体的血清中有71份（96%）显示CMV AI值>60%。因此，内部ELISA中的低亲和力被定义为AI≤50%，而高亲和力被定义为AI≥60%。在其他研究中，使用64份在CMV IgM捕获ELISA（Diamedix）中显示不确定或阳性结果的CMV IgG阳性血清（血清学转换后的时间未知），检测了CMV IgG亲和力与CMV IgM水平之间的关系。在这64份血清中，29份显示IgM指数值≥3.0，这29份中的27份（93%）显示低IgG亲和力。当在另一种CMV IgM捕获ELISA（Trinity）中对这64份血清的一个子集（n = 48）进行检测时，观察到了类似的趋势；在18份IgM指数值≥3.0的血清中，17份（94%）显示低IgG亲和力。这些发现证明了用于CMV IgG亲和力的内部ELISA的有效性，并进一步表明，在两种CMV IgM捕获测定中的任何一种中，CMV IgG阳性血清的强反应性是低CMV IgG亲和力的可靠指标，因此也是近期CMV感染的可靠指标。
