Metaperiodate deglycosylation of Strongyloides venezuelensis larvae: Immunochemical characterization and antigen production for human strongyloidiasis diagnosis.

Strongyloidiasis is an important helminthiasis affecting million people worldwide. The aim of this study was to use sodium metaperiodate (MP) treatment to immunochemically characterize Strongyloides venezuelensis filariform larvae and use MP-treated heterologous antigen to detect IgG and subclasses in serum. Samples from individuals with definitive diagnosis of strongyloidiasis (n = 50), other parasitic diseases (n = 60) and negative endemic (n = 50) were tested. TG-ROC and two-way ANOVA were applied. MP-treatment resulted on differential localization of carbohydrates at larval structure and no carbohydrate content in saline extract (SE). Electrophoretic profiles were similar before and after treatment. ELISA sensitivity and specificity were: 90%; 88.2% for SE and 92.0%; 94.6% for MP, respectively. When using MP treated antigen we observed reduction in IgG1 and IgG3 detection in strongyloidiasis group and decrease of cross reactions in control groups. Our data demonstrate the role of carbohydrate residues in cross reactions and on the recognition of anti-Strongyloides IgG and its subclasses.

Bacteriophage-fused peptides for serodiagnosis of human strongyloidiasis.

BACKGROUND: Strongyloidiasis, a human intestinal infection caused by the nematode Strongyloides stercoralis, is frequently underdiagnosed and although its high prevalence is still a neglected parasitic disease because conventional diagnostic tests based on parasitological examination (presence of Strongyloides larvae in stool) are not sufficiently sensitive due to the low parasitic load and to the irregular larval output. There is an urgent need to improve diagnostic assays, especially for immunocompromised patients with high parasitic load as consequence of self-infection cycle, which can disseminate throughout the body, resulting in a potentially fatal hyperinfection syndrome often accompanied by sepsis or meningitis. METHODS/PRINCIPAL FINDINGS: We have performed Phage Display technology to select peptides that mimic S. stercoralis antigens, capable of detecting a humoral response in patients with strongyloidiasis. The peptides reactivity was investigated by Phage-ELISA through different panels of serum samples. We have successfully selected five peptides with significant immunoreactivity to circulating IgG from patients' sera with strongyloidiasis. The phage displayed peptides C9 and C10 presented the highest diagnostic potential (AUC>0.87) with excellent sensitivity (>85%) and good specificity (>77.5%), suggesting that some S. stercoralis antigens trigger systemic immune response. CONCLUSIONS/SIGNIFICANCE: These novel antigens are interesting serum biomarkers for routine strongyloidiasis screenings due to the easy production and simple assay using Phage-ELISA. Such markers may also present a promising application for therapeutic monitoring.

Hydrophobic fractions from Strongyloides venezuelensis for use in the human immunodiagnosis of strongyloidiasis.

The objective of the present research was to evaluate detergent and aqueous phases of total saline (TS) and alkaline extracts of Strongyloides venezuelensis for human strongyloidiasis immunodiagnosis. Total extracts and detergent and aqueous antigenic fractions were separated using Triton X-114 and were examined by enzyme-linked immunosorbent assay (ELISA) and immunoblotting (IB) tests to detect immunoglobulin G (IgG). Serum samples were obtained from 120 individuals: 40 strongyloidiasis patients (group I), 40 patients with other parasitic diseases (group II), and 40 apparently healthy individuals (group III). Each extract provided a different profile of antigenic components as recognized by IgG in IB. The detergent fraction of the TS extract demonstrated the highest sensitivity and specificity for ELISA and IB. The results indicated that the detergent saline fraction, purified from S. venezuelensis, furnished the most valid results for the strongyloidiasis immunodiagnosis and could be employed as an alternative antigen and as a useful source of specific polypeptides.

Modulatory role of melatonin on superoxide release by spleen macrophages isolated from alloxan-induced diabetic rats.

UNLABELLED: The aim of this study was to evaluate the modulatory effect of melatonin on superoxide release by spleen macrophages isolated from alloxan-induced diabetic insulin treated or non-treated rats. METHODS: Blood glucose, body weight, CuZn-superoxide dismutase concentration, and superoxide release by spleen macrophages were evaluated. RESULTS: The spontaneous superoxide release from the macrophages of the control group was lower when compared to diabetic rats without insulin treatment. Melatonin (MLT) significantly increased the superoxide release in the control group (11.5 +/- 1.5 with MLT x 6.8 +/- 1.0 without MLT). The macrophages from diabetic rats treated with insulin exhibited a decreased superoxide release (7.0 +/- 2.4), when compared to superoxide release of the macrophages from diabetic rats without insulin (14.7 +/- 3.7). CuZn-SOD concentrations were increased in both diabetic groups. CONCLUSION: The pineal hormone melatonin in physiological concentration can stimulate natural immunity since it triggers the superoxide release from the macrophages, an important anti-infectious mechanism. On the other side, melatonin had antioxidant effects in the macrophages from insulin-treated alloxan-induced diabetic rats (Tab. 1, Fig. 2, Ref. 51).