Bobić Branko, Klun Ivana, Vujanić Marija, Nikolić Aleksandra, Ivović Vladimir, Živković Tijana, Djurković-Djaković Olgica
National Reference Laboratory for Toxoplasmosis, Serbian Centre for Parasitic Zoonoses, Institute for Medical Research, University of Belgrade, Belgrade, Serbia.
J Med Microbiol. 2009 Mar;58(Pt 3):358-364. doi: 10.1099/jmm.0.006668-0.
Determination of the avidity of specific IgG antibodies has become a generally accepted diagnostic aid for dating Toxoplasma infection. In this study, the Labsystems, VIDAS and EUROIMMUN Toxoplasma IgG avidity assays were compared on a series of 133 Toxoplasma IgG- and IgM-positive sera from symptomatic patients (n=28), from pregnant (n=43) and non-pregnant (n=26) women, and on 18 IgG-positive and IgM-negative sera from chronically infected patients. The results showed excellent concordance between the Labsystems and VIDAS tests in both the IgM-positive (r=0.82, kappa=0.771) and IgM-negative (kappa=0.609) sera, whilst the agreement of the EUROIMMUN assay with both the Labsystems and VIDAS tests in the IgM-positive sera was moderate (kappa=0.575 and kappa=0.525, respectively) and in the IgM-negative sera was poor (kappa=0.000). Analysis of the kinetics of the maturation of avidity in 13 patients in whom follow-up sera were available showed that, despite a general trend of maturation, in two patients the avidity did not become high during 6 and 11 months of follow-up. In view of the clinical setting, in the symptomatic patients, despite one case of complete discrepancy and five cases of partial discrepancy, the Labsystems and VIDAS tests were in almost perfect agreement (kappa=0.812), whilst the agreement in pregnant and non-pregnant women was substantial (kappa=0.754 and kappa=0.708, respectively). In conclusion, the Labsystems and VIDAS tests are equally reliable for the measurement of Toxoplasma IgG avidity; the choice of test should depend on the laboratory set-up. The EUROIMMUN test may be an acceptable alternative in resource-limited settings, but should be used prudently.
测定特异性IgG抗体的亲和力已成为确定弓形虫感染时间的一种普遍接受的诊断辅助手段。在本研究中，对Labsystems、VIDAS和EUROIMMUN弓形虫IgG亲和力检测方法进行了比较，检测对象包括133份来自有症状患者（n = 28）、孕妇（n = 43）和非孕妇（n = 26）的弓形虫IgG和IgM阳性血清，以及18份来自慢性感染患者的IgG阳性和IgM阴性血清。结果显示，Labsystems和VIDAS检测方法在IgM阳性血清（r = 0.82，kappa = 0.771）和IgM阴性血清（kappa = 0.609）中具有极好的一致性，而EUROIMMUN检测方法与Labsystems和VIDAS检测方法在IgM阳性血清中的一致性为中等（kappa分别为0.575和0.525），在IgM阴性血清中的一致性较差（kappa = 0.000）。对13例有随访血清的患者的亲和力成熟动力学分析表明，尽管总体上有成熟趋势，但有2例患者在6个月和11个月的随访期间亲和力未升高。鉴于临床情况，在有症状患者中，尽管有1例完全不一致和5例部分不一致的情况，但Labsystems和VIDAS检测方法几乎完全一致（kappa = 0.812），而在孕妇和非孕妇中的一致性较高（kappa分别为0.754和0.708）。总之，Labsystems和VIDAS检测方法在测量弓形虫IgG亲和力方面同样可靠；检测方法的选择应取决于实验室设置。EUROIMMUN检测方法在资源有限的环境中可能是一种可接受的替代方法，但应谨慎使用。
