Roque-Afonso Anne-Marie, Grangeot-Keros Liliane, Roquebert Bénédicte, Desbois Delphine, Poveda Jean-Dominique, Mackiewicz Vincent, Dussaix Elisabeth
Centre National de Référence pour les Virus à Transmission Entérique, Hôpital Paul Brousse, Villejuif, France.
J Clin Microbiol. 2004 Nov;42(11):5121-4. doi: 10.1128/JCM.42.11.5121-5124.2004.
Diagnosis of acute hepatitis A virus (HAV) infection is based on the detection of HAV immunoglobulin M (IgM). However, IgM could be detected due to nonspecific polyclonal activation of the immune system. An avidity test for anti-HAV IgG was developed to distinguish acute infection, where low-avidity antibodies are detected, from immune reactivation. The assay was tested on 104 samples, including 11 sera from patients with past infection, 15 sera from patients with acute infection and 4 collected after recovery, 10 sera from vaccinated subjects, 4 sera from patients with suspected immune reactivation, and 60 unselected HAV-IgM positive sera, collected over 1 year in a routine laboratory. The avidity index (AI) was expressed as percentage. The results were provided as the mean +/- one standard deviation. Patients with a history of prior infection had AIs of >70% (mean, 86% +/- 10), whereas the mean AI was 36% +/- 16 during acute HAV infection (P < 0.001). Within the first month after the onset of hepatitis, avidity was either noncalculable due to a very low IgG titer or <50%. In patients with immune reactivation, avidity was >70% (88% +/- 10%), a finding consistent with a prior infection. Among the 60 unselected sera, 35 (58%) had a noncalculable or <50% avidity, and most of them had a detectable HAV RNA, confirming HAV infection. In contrast, 16 (27%) had an avidity of >70%, and none was reverse transcription-PCR positive, suggesting immune reactivation. These 16 patients were significantly older than the others (50 +/- 16 years versus 26 +/- 14 years). The new anti-HAV IgG avidity assay we developed could improve HAV infection diagnosis, particularly in elderly patients.
急性甲型肝炎病毒（HAV）感染的诊断基于HAV免疫球蛋白M（IgM）的检测。然而，由于免疫系统的非特异性多克隆激活也可能检测到IgM。为区分急性感染（检测到低亲和力抗体）和免疫再激活，开发了一种抗HAV IgG亲和力检测方法。该检测方法在104份样本上进行了测试，其中包括11份既往感染患者的血清、15份急性感染患者的血清、4份康复后采集的血清、10份接种疫苗者的血清、4份疑似免疫再激活患者的血清，以及60份在常规实验室1年多时间里收集的未筛选的HAV-IgM阳性血清。亲和力指数（AI）以百分比表示。结果以平均值±一个标准差给出。既往有感染史的患者AI>70%（平均值，86%±10%），而急性HAV感染期间的平均AI为36%±16%（P<0.001）。在肝炎发病后的第一个月内，由于IgG滴度非常低，亲和力要么无法计算，要么<50%。在免疫再激活的患者中，亲和力>70%（88%±10%），这一发现与既往感染一致。在60份未筛选的血清中，35份（58%）的亲和力无法计算或<50%，其中大多数可检测到HAV RNA，证实为HAV感染。相比之下，16份（27%）的亲和力>70%，且均为逆转录聚合酶链反应阴性，提示免疫再激活。这16名患者明显比其他患者年龄大（50±16岁对26±14岁）。我们开发的新的抗HAV IgG亲和力检测方法可改善HAV感染的诊断，尤其是在老年患者中。
