Taenia saginata metacestode antigenic fractions without affinity to concanavalin A are an important source of specific antigens for the diagnosis of human neurocysticercosis

Antigen Recognition Patterns of Intestinal Capillariasis Using Immunoblot-Based Serodiagnosis

BACKGROUND

Diagnosis of intestinal capillariasis depending on microscopic detection of parasitic stages is of low sensitivity, especially in cases with low worm burden. There is a necessity to develop sensitive and specific diagnostic tools of capillariasis for early treatment to avoid complications. Western blot (WB) technique showed promising results for antigen recognition patterns in several parasitic infections.

AIM OF THE STUDY

This study is directed to identify and evaluate relevant proteins of intestinal capillariasis crude worm antigens using WB immunodiagnosis.

MATERIALS AND METHODS

Capillaria crude worm antigens were extracted and analyzed using SDS-PAGE. Sixty serum samples belonging to 3 groups (20 individuals each) were included; Group I (shedding Capillaria in feces), Group II (infected with other parasites) and Group III (negative parasitological results). Reactivity of the resulting bands of Capillaria with serum samples was analyzed using WB technique.

RESULTS

Thirty-two immunoreactive bands were detected in WB analysis representing recognition of proteins with molecular weights (MW) varying from 19 to 110 kDa. Immunodominant proteins of 23.5, 31, 36.5, 40.5 and 44 kDa were recognized, respectively, in 35%, 30%, 85%, 95% and 75% of sera from patients with confirmed capillariasis and in 30%, 25%, 35%, 25%, and 20% of sera from those infected with other parasitic infections. One serum sample from group III gave reaction with 31 kDa band.

CONCLUSION

Immunodiagnosis of intestinal capillariasis using WB proved that 23.5, 31, 36.5, 40.5 and 44 kDa bands could be considered useful tools for diagnosis of capillariasis.

Usefulness of gel filtration fraction as potential biomarker for neurocysticercosis in serum: towards a new diagnostic tool

There is an increasing interest in improving neurocysticercosis (NCC) diagnosis through the search of new and alternative antigenic sources, as those obtained from heterologous antigens. The aim of this study was to obtain potential biomarkers for NCC diagnosis after gel filtration chromatography [gel filtration fraction (GFF)] from the total saline extract (SE) from Taenia saginata metacestodes, followed by protein identification and application in immunodiagnostic. SE and GFF proteic profiles were characterized in gel electrophoresis, and diagnostic performance was verified by testing 160 serum samples through enzyme-linked immunosorbent assay and immunoblotting. Sensitivity (Se), specificity (Sp) and other diagnostic parameters were calculated. Polypeptides of interest in the diagnosis of human NCC present at GFF were analysed by mass spectrometry (MS) and B-cell epitopes were predicted. GFF had the best diagnostic parameters: Se 93·3%; Sp 93%; AUC 0·990; LR+ = 13·42 and LR− = 0·07, and proved to be useful reacting with serum samples in immunoblotting. Proteic profile ranged from 64 to 68 kDa and enolase and calcium binding protein calreticulin precursor were identified after MS. The enolase and calcium-binding protein calreticulin precursor showed 18 and 10 predicted B-cell epitopes, respectively. In conclusion we identified important markers in the GFF with high efficiency to diagnose NCC.

An immunoblot for detection of Taenia saginata cysticercosis

Control measures to prevent human infections with the food-borne zoonotic helminth Taenia saginata are currently based on meat inspection, which shows rather low diagnostic sensitivity. To develop an immunoblot for detection of T. saginata-infected cattle, crude proteins of T. saginata cysts were extracted and separated with SDS-PAGE. The cyst antigens showed ten protein bands ranging from 260 to 14 kDa. T. saginata cyst proteins 260, 150, 130, 67, 60, 55, 50, and 23 kDa were immunoreactive with known positive sera of T. saginata-infected cattle but cross-reacted with sera from Echinocccus granulosus-infected ruminants. By contrast, 14- and 18-kDa cyst proteins reacted specifically with T. saginata-positive sera and thus might be potential candidates for the development of a T. saginata-specific immunoassay. Proteins of E. granulosus cysts and Taenia hydatigena cysts were also extracted and separated with SDS-PAGE. E. granulosus cysts revealed 11 protein bands ranging from 260 to 23 kDa. E. granulosus protein 60 kDa was immunoreactive with E. granulosus-positive sera only. The cyst of T. hydatigena showed 11 protein bands ranging from 290 to 14 kDa. The protein band 35 kDa showed cross-reaction with positive sera from both T. saginata- and E. granulosus-infected animals. A protein of 67 kDa was present in all three tested cestode species and was the major antigenic protein detected by sera of T. saginata- and E. granulosus-infected animals. Therefore, this protein represents a potential vaccine candidate against both cysticercosis and cystic echinococcosis in cattle.

Taenia saginata metacestode antigenic fractions obtained by ion-exchange chromatography: potential source of immunodominant markers applicable in the immunodiagnosis of human neurocysticercosis

The aim of this study was to fractionate and partially characterize fractions obtained from the total saline extract (SE) of Taenia saginata metacestodes after ion-exchange procedure in carboxymethyl sepharose (CM) and diethylaminoethyl sepharose (DEAE) resins, as a source of antigenic markers applicable in the immunodiagnosis of neurocysticercosis (NCC). For IgG detection by enzyme-linked immunosorbent assay (ELISA) and immunoblotting, 140 serum samples were analyzed: 45 from patients with NCC (G1), 50 from patients with other parasitic infections (G2), and 45 from healthy individuals. Sensitivity (Se), specificity (Sp), area under curve (AUC), and likelihood ratios (LR) were calculated. CM S2 and DEAE S2 fractions provided high diagnostic values (Se 88.8% and 93.4%; Sp 93.7% and 92.6%; AUC 0.965 and 0.987; LR+ 14.07 and 12.67; LR- 0.11 and 0.07, respectively). In conclusion, CM S2 and DEAE S2 fractions are important sources of specific peptides, with high efficiency to diagnose NCC.

Use of heterologous antigens for the immunodiagnosis of abdominal angiostrongyliasis by an enzyme-linked immunosorbent assay

Angiostrongylus costaricensis has a broad geographic distribution spanning from North to South America and the infections of vertebrates with this nematode can result in abdominal complications. Human infections are diagnosed by histological or serological methods because the isolation of larvae from feces is not feasible, as most parasites become trapped in intestinal tissues due to intense eosinophilic inflammation. Because A. costaricensis is difficult to maintain in the laboratory, an immunodiagnostic IgG enzyme-linked immunosorbent assay (ELISA) using antigens from the congeneric Angiostrongylus cantonensis species was evaluated against a panel of serum samples from patients who were histologically diagnosed with A. costaricensis infections. Sera from uninfected individuals and individuals infected with other parasites were used as controls. The sensitivity and specificity of the assay were estimated at 88.4% and 78.7%, respectively. Because the use of purified or cloned antigens has not been established as a reliable diagnostic tool, the use of heterologous antigens may provide a viable alternative for the development of an ELISA-based immunodetection system for the diagnosis of abdominal angiostrongyliasis.