Comparative Analysis of the Diagnostic Performance of Six Major Echinococcus granulosus Antigens Assessed in a Double-Blind, Randomized Multicenter Study

Abstract

The serodiagnosis of hydatid disease is a valuable instrument for clinical diagnosis and epidemiological surveillance of high-risk populations. In the past decade a wealth of reports on the diagnostic performance of numerous antigens have been produced. However, their diagnostic value has been estimated under different conditions, using different serum collection, therefore precluding their direct comparison. Here we report an unbiased comparison of the same batch of six major E. granulosus antigens, namely, hydatid cyst fluid (HCF), native antigen B (AgB), two recombinant AgB subunits, an AgB-derived synthetic peptide, and recombinant cytosolic malate dehydrogenase from E. granulosus (EgMDH), against the same serum collection. The doubleblind analysis was performed using a standardized protocol and receiver operating characteristic (ROC) data analysis by a network of six South American laboratories. High intercenter reproducibility was attained, and the intralaboratory analysis allowed the comparative ranking of the antigen panel. HCF, AgB, and its AgB8/1 subunit exhibited equivalent diagnostic efficiencies, 81.4% ؎ 0.5%, 81.3% ؎ 0.6%, and 81.9% ؎ 2.0%, respectively; with a more favorable balance toward specificity in the case of the last antigen. The diagnostic efficiencies for the other three antigens were 76.8% ؎ 6.8%, 69.1% ؎ 2.7%, and 66.8% ؎ 2.1%, for the peptide, the AgB8/2 subunit, and the EgMDH, respectively. The study also included an analysis of batch-to-batch variation in the diagnostic performance of different HCF regional preparations. Based on these results, a suggested recommendation on the use of these antigens was drawn.

Serological diagnosis of echinococcosis: the diagnostic potential of native antigens

“…Additionally, tests based on the partially purified lipoproteins antigen B (AgB) and antigen 5 (both found in the germinal membrane, protoscolex parenchyma and cyst fluid [36]) are used either in ELISA or immunoblot assays. The major drawback of these tests is the lack of species specificity, as cross-reactions between AE and CE and many other helminthic infections are commonly observed (cestodes, 89%; nematodes, 39%; trematodes; 30%) [5,20,[37][38][39][40]. Assays based on a recombinant subunit of AgB, denoted rAgB8/2, showed sensitivities of 45-93% and specificities of 86-99% with the same cross-reactions as mentioned above [20,41,42].…”

“…Thus, differences in diagnostic performance in terms of sensitivity, specificity and crossreactivity have to be expected. Nevertheless, a comparative analysis by Lorenzo [20] and colleagues of the diagnostic potential of EgHF from six different batches applied on the same sera displayed differences in the intensity of the reaction, but there was no impact on the diagnostic parameters.…”

Recent Advances in the Immunology and Serological Diagnosis of Echinococcosis

“…Table 4 shows the performance of antigen 5 for serological diagnosis of human CE. Loss of sugar determinants on antigen 5 can reduce the antigenicity of the native protein (Lorenzo et al, 2005a). The potential value of specific antibodies of different IgG subclasses and IgE in serological diagnosis of CE using an ELISA based on Ag5 has been evaluated (Khabiri et al, 2006).…”

Isolation and molecular characterization of recombinant Echinococcus granulosus P29 protein (recP29) and its assessment for the post-surgical serological follow-up of human cystic echinococcosis in young patients

“…17 Most of these studies preliminarily documented a high diagnostic performance of the recombinant antigens. 9,[14][15][16]18,19 Alternatively, synthetic peptides including p176, 20,21 derived from the antigen B sequence, and the 89-122, which mimics an epitope of Ag5, 22 also provided interesting findings. Unfortunately, these recombinant antigens and synthetic peptides were not (or only poorly) investigated for their prognostic value in the serological follow-up of CE.…”