Specific IgG Responses to Recombinant Antigen B and Em18 in Cystic and Alveolar Echinococcosis in China

Abstract

An understanding of the correlation of the specific antibody responses and the disease phase is essential in evaluating diagnostic values of immunological tests in human echinococcosis. In this study, 422 echinococcosis patients diagnosed by ultrasonography, including 246 with cystic echinococcosis (CE), 173 with alveolar echinococcosis (AE), and 3 with dual infection, were tested for specific IgG in sera against recombinant AgB (rAgB) and recombinant Em18 (rEm18) in an enzyme-linked immunosorbent assay. As a result, rAgB-specific antibody was detected in 77.6% of CE and 86.1% of AE patients, while rEm18-specific antibody was present in 28.9% of CE and 87.3% of AE patients. Additionally, all three patients with dual infection exhibited specific antibodies responding to rAgB and rEm18. Further analysis revealed that rAgB-specific antibody was elevated in a significantly greater proportion (87.3%) of CE patients with cysts at active or transitional stages (CE1, CE2, or CE3), compared to 54.8% of other patients with cysts at an early or an inactive stage (CL or CE4 or CE5). Furthermore, rAgB-specific antibody was detected in 95.6% of CE2 cases, which was statistically greater than that (73.7%) in CE1 patients. Although rEm18-specific antibody was elevated in 28.9% of CE patients, the positive reaction was much weaker in CE than in AE cases. Serum levels and concentrations of rEm18-specific antibody were further indicated to be strongly disease phase correlated in AE patients, with positive rates of 97.4% in cases with alveolar lesions containing central necrosis and 66.7% in patients with early alveolar lesions that measured <5 cm.Humans acquire the infection of echinococcosis by accidental ingestion of eggs excreted with feces of carnivores harboring the adult worms of Echinococcus spp. The eggs hatch in the small intestine of humans, releasing the oncosphere, which migrates via the portal system into various organs and then develops into the metacestode stage. The larval parasite can establish itself in any part of the human body but most frequently does so in the liver (32). Diagnosis of human echinococcosis is primarily based on the pathognomonic features in images obtained using imaging techniques including ultrasonography, computed tomography (CT), and magnetic resonance imaging (MRI). Of these techniques, B-ultrasound is much more widely applied, as CT and MRI are too expensive and largely inaccessible in most areas where echinococcosis is endemic. Criteria for classification of cystic echinococcosis (CE) and alveolar echinococcosis (AE) have been proposed based on stage-specific ultrasound images (20,36). Briefly, on the basis of conformational features of cysts, CE lesions are differentiated into six types: CL, CE1, CE2, CE3, CE4, and CE5. The CL type refers to a cystic lesion of a parasite origin and without a clear rim, indicating the parasite is at a very early stage of development. The CE1 type describes a unilocular simple cyst with uniform anechoic content and, importantly, with a visible wall, while...

Serological diagnosis of echinococcosis: the diagnostic potential of native antigens

“…Mamuti and colleagues [47] used a recombinant AgB8/1, reporting sensitivities of 88.0% (95% CI 75.7-95.5%) for CE and 37.8% (95% CI 23.7-53.5%) for AE. In another study by Li and colleagues [48], a recombinant AgB subunit 8, basically prepared as described by Mamuti and colleagues [47], reached sensitivities of 77.6% (95% CI 77.6-82.7%) for CE and 85.0% (95% CI 78.8-89.9%) for AE; in terms of AE, this is significantly more sensitive than that reached by Mamuti and colleagues with the recombinant AgB8/1, but not more sensitive than that found in our study using native AgB ([99.9%; 95% CI 94.3-100%). Sensitivities for CE did not differ significantly between all three studies and were comparable with the results of a study by Gihan and colleagues [49] where a sensitivity of 82.5% (95% CI 73.2-95.8%) was reported.…”

Factors Influencing the Serological Response in Hepatic Echinococcus granulosus Infection

“…The stage of the cyst is the variable most often investigated in correlation with serology results, with a consensus finding that patients with CE1 and CE4-CE5 (hepatic) cysts are seronegative in a high percentage of cases (30-58% and 50-87%, respectively), while rates of negativity are lower in the presence of CE2 and CE3 cysts (5-20%). 10,[12][13][14] When the variables associated with serology results were investigated in more detail, serodiagnosis performance correlated with stage, number (single versus multiple), location (liver versus lungs), and size (< or > than 15 cm) of cysts; presence of complications; and collection of serum after treatment. 10,11,13,15 Although in the majority of cases of hepatic CE the combined use of imaging and serology allows for a reliable diagnosis, in some instances they are inconclusive, and differential diagnosis with other lesions may be challenging.…”

Evaluation of a New Immunochromatographic Test Using Recombinant Antigen B8/1 for Diagnosis of Cystic Echinococcosis

“…ELISA was carried out in flatbottom 96-well microplates (Nunc, Maxisorp, Roskilde, Denmark) as previously described (18). The microplates were coated with 100 ng/ml of rAgB diluted in phosphate-buffered saline (PBS) and incubated at 4°C overnight.…”