Route of dexamethasone administration influences parasite burden in Strongyloides hyperinfection model.

Rodents infected with Strongyloides venezuelensis are experimental models applied to strongyloidiasis research. This study evaluated oral and subcutaneous dexamethasone (DEX) treatments to establish immunosuppression in an experimental model of Strongyloides hyperinfection. Rattus norvegicus Wistar were divided: G I (-): untreated and uninfected animals, G II (+): untreated and infected, G III (o -) orally treated and uninfected, G IV (o +) orally treated and infected, G V (sc -) subcutaneously treated and uninfected, G VI (sc +) subcutaneously treated and infected. For oral administration, DEX was diluted in sterile water (5 µg/ml) and made available to the animals on intervals in experimental days - 5-0, 8-13 and 21-26. For subcutaneous administration, animals received daily injections of DEX disodium phosphate (2 mg/kg). Infection was established by the subcutaneous inoculation of 3000 S. venezuelensis filarioid larvae. Groups were evaluated by egg per gram of feces and parasite females counts and IgG, IgG1 and IgG2a detection. GIV (o +) had egg peaks count on days 13 and 26 and maintained egg elimination until the last experimental day. Parasitic females recovery at day 30 was significantly higher in G IV (o +) when compared to G VI (sc +). Levels of IgG, IgG1 and IgG2a of all groups, except the positive control GII (+), were below the detection threshold. Pharmacological immunosuppression induced by oral administration of DEX produced high parasitic burden, and is a noninvasive method, useful to establish immunosuppression in strongyloidiasis hyperinfection model in rats.

Jacalin-unbound fraction of Taenia saginata in immunodiagnosis of neurocysticercosis in human cerebrospinal fluid.

The aim of this study was to evaluate jacalin-bound fraction (JBF) and jacalin-unbound fraction (JUF) of the total saline extract from Taenia saginata metacestodes for human neurocysticercosis (NC) immunodiagnosis in cerebrospinal fluid. Total extract, JBF, and JUF were separated by affinity chromatography using Sepharose(®)-jacalin and were tested in enzyme-linked immunosorbent assay (ELISA) and Western blotting (WB) to detect immunoglobulin G. In ELISA test, JUF showed the higher diagnostic efficiency and specificity indexes, 92% and 100%, respectively. In WB, 5 immunodominant proteins (39-42, 47-52, 64-68, 70, and 75 kDa) were detected when using JUF. In conclusion, the results achieved demonstrate that JUF, obtained from T. saginata metacestodes, are an important source of specific peptides and are efficient in the diagnosis of NC.

Selection of high affinity peptide ligands for detection of circulating antibodies in neurocysticercosis.

Neurocysticercosis (NC), caused by Taenia solium, is the most common infection caused by helminthes of the human central nervous system. In this study, a random peptide phage display library was used to isolate peptide ligands as potential markers for neurocysticercosis diagnosis, because occurrence of cross-reactions with other helminthes species in the current used markers. We selected different peptides using IgG purified from pooled sera of neurocysticercosis patients. To investigate the diagnostic potential of recombinant peptides, we have tested different panels of serum samples by Phage-ELISA, and 10 phage clones strongly bound to the anti-T. solium IgGs in NC sera, with an accuracy range from 84.2% to 95%. The phage clones, NC(4)1 and NC(2)8, presented the highest sensitivity and specificity (100%), respectively, and most important, some phage clones did not react with patients' sera from Echinococcus granulosus infected patients. The validation with a competitive ELISA assay demonstrated that the selected phages could mimic T. solium epitopes and bind specifically to the pool of NC sera. Finally, the two recombinant antigens may become potential biomarkers for serodiagnosis of NC, and the Phage-ELISA demonstrated to be a very good assay, being reproducible, simple, fast, and low-cost due to its production through Escherichia coli culture, allowing a high throughput screening of NC.

Specific IgG avidity in active and inactive human neurocysticercosis.

IgG avidity determination in serum samples was investigated to distinguish active and inactive human neurocysticercosis (NC). High avidity index (>70%) was found in 23.5% of cases in active group and 67.9% in inactive group (P = 0.0058). We reported for the first time that IgG avidity assay may distinguish active from inactive NC.