Diagnostic accuracy of somatic and excretory−secretory antigens from Strongyloides venezuelensis infective larvae for the immunodiagnosis of human strongyloidiasis

Abstract

Abstract

Evaluation of larval surface antigens from infective larvae of Strongyloides venezuelensis for the serodiagnosis of human strongyloidiasis

“…Nevertheless, the main limitation of this procedure is the use of live parasites in a cell culture medium or PBS at 37 °C for extracting the surface cuticle antigens, since these physiological conditions may stimulate the release of E/S products by live parasites, thus contaminating the extraction of the surface antigens. Our procedure differs from these previous authors in the use of frozen larvae, since live S. venezuelensis larvae were capable of releasing considerable amounts of E/S products when incubated in PBS for 48 h at 37 °C 12 . This modification guarantees that our CTAB antigenic extract contains only proteins from the surface of the larvae.…”

“…S. venezuelensis iL3 were obtained from 48 h charcoal fecal cultures from male Wistar rats ( Rattus norvegicus ) who were experimentally infected at 30 days of age. These iL3 were recovered by using a modified Baermann’s technique; the larvae were treated with sodium hypochlorite 0.25% for 5 min and then washed four times with sterile distilled water by centrifugation at 4,000 x g for 1 min at room temperature in the Eppendorf Centrifuge model 5427 R (Eppendorf ® SE, Germany), and then stored at -20 °C until use 12 . The rats received sterilized food and water ad libitum and were handled in compliance with the animal ethics guidelines adopted by the Animal Research Ethics Committee of FMUSP (protocol Nº 0356A).…”

“…ELISA for the detection of IgG antibodies was based on the procedure described by Roldán Gonzáles et al 12 . Briefly, the Costar ® 96-well flat bottom microtitration polystyrene plates (Sigma-Aldrich Chemical Co., St. Louis, MO, USA) were coated (100 μL/well) with each type of the antigenic extracts at a concentration of 10 μg/mL, diluted in carbonate-bicarbonate buffer (0.06 M, pH 9.6) and incubated overnight at 4 °C.…”

“…Although maximum sensitivity can be obtained with these types of antigenic extracts, their main limitation is the cross-reactivity with other types of helminths. On the other hand, excretory-secretory products from infective larvae (iL3) of S. venezuelensi obtained under in vitro conditions have shown to have excellent values of sensitivity and specificity and almost no cross-reactivity, but their production is very time consuming 12 . During their migration through host tissues, the cuticle surface of Strongyloides larvae is in direct contact with the immune system, being the main target for the immune response.…”

Seroprevalence and associated risk factors of strongyloidiasis in indigenous communities and healthcare professionals from Brazil

“…0356A). The iL3 were recovered using a modified Baermann technique: the larvae were treated with 0.25% sodium hypochlorite for 5 minutes, then washed four times with sterile distilled water and centrifuged at 4,000 x g for one minute, and then stored at -20°C until use [ 32 ]. The second was made from surface cuticle from S .…”