A filtration-based rapid test using a partially purified third-stage larval antigen to detect specific antibodies for the diagnosis of gnathostomiasis

Abstract

Human gnathostomiasis is an emerging food-borne parasitic disease caused by nematodes of the genusGnathostoma. Currently, serological tests are commonly applied to support clinical diagnosis. In the present study, a simple and rapid filtration-based test, dot immune–gold filtration assay (DIGFA) was developed using a partially purified antigen ofGnathostomathird-stage larvae (L3). A total of 180 serum samples were tested to evaluate the diagnostic potential of DIGFA for gnathostomiasis. The diagnostic sensitivity and specificity were 96.7% (29/30) and 100% (25/25), respectively. The cross-reactivity with sera from other helminthiasis patients ranged from 0 to 4%, with an average of 1.6% (2/125). DIGFA using a partially purified L3 antigen was not only simple and rapid, but also more accurate than standard assays for the diagnosis of human gnathostomiasis. DIGFA may represent a promising tool for application in laboratories or in the field, without requiring any instrumentation.

Evaluation of Rapid IgG4 Test for Diagnosis of Gnathostomiasis

“…In this study, the rapid format DIGFA using L3 crude extract as antigen for detection of specific IgG4 against Gnathostoma presented 100% in both sensitivity and specificity for the diagnosis of gnathostomiasis, decreased cross-reactivity with other helminthiases, and increased specificity with respect to total IgG test by DIGFA [ 16 ]. The result of this study tallied with the data obtained previously by immunoblot analysis [ 15 , 24 , 25 ].…”

“…Specificity in sero-diagnosis of human helminthiasis could be enhanced by removing immune response to phosphocholine, carbohydrate, and polysaccharide antigens, which usually leads to false-positive reactions [ 26 , 27 ]. In our previous studies, the native L3 extract antigen-removed polysaccharide antigens by TCA/acetone precipitation had high specificity for gnathostomiasis diagnosis [ 16 ]. In this study, IgG4-based DIGFA using crude L3 extract attained similar diagnostic sensitivity and specificity as total IgG detection by DIGFA using partially purified L3 antigen.…”

“…The DIGFA comprised of test cassettes, colloidal gold conjugated with mouse anti-human IgG4 monoclonal antibody (McAb) and washing buffer. The test cassettes were assembled as previously described [ 16 ]. Two dots consisting of 0.5 μl of human IgG4 (0.1 mg/ml) used as positive control and 0.5 μl of L3 crude antigen (1 mg/ml) were put separately at the sides of “C” (positive control dot) and “T” (test dot) on the centre of nitrocellulose membrane ( Fig.…”

“…1 ). For the preparation of anti-human IgG4-conjugated colloidal gold solution, 100 ml of mono-disperse gold solution (pH 8.5) was obtained according to the method described previously [ 16 ]. Then, it mixed with 0.25 mg of mouse anti-human IgG4 Fc antibody (Thermo fisher, Carlsbad, California, USA) by stirring.…”

Evaluation of immunodiagnostic tests for human gnathostomiasis using different antigen preparations of Gnathostoma spinigerum larvae against IgE, IgM, IgG, IgG1‐4 and IgG1 patterns of post‐treated patients

“…Several strategies to improve the reliability of diagnosis suggested promising results based on the evaluation of immunoglobulins specific to G . spinigerum infection, use of various types of Ag and infections with a large number of different parasites [ 4 , 5 , 8 , 15 , 16 , 17 , 18 ].…”