Diagnosis of cysticercosis by dot immuno-gold filtration assay for rapid detection of specific IgG4

Abstract

Objective To develop a simple,rapid and sensitive immunoassay and sero-immunological diagnostic kits for diagnosis of cysticercosis. Methods Crude extracts of cyst fluid of Cysticercns cellulosae were used as antigens and anti-human IgG4 McAb was conjugated with colloidal gold as the detecting probe. A special pad for vertical-flow filtra-tion assay was designed according to the reaction procedure to detect specific IgG4 or IgG against cyticercus in patient sera. ELISA kit for determination of cyticercus IgG4 was utilized as control to evaluate, the new rapid assay. Results The sensi-tivity and specificity of this new rapid immunoassay for specific IgG4 against cysticercus were 95.7 % (90/94) and 100.0%(50/50) respectively, which were close to the results of IgG detection. There were 8.0% and 8.3% of cross reactions with patient sera of echinococcosis and of sparganosis, lower than those of IgG detection. None cross reaction showed with other helminthiasis such as schistosomiasis and paragonimiasis infection. In compared with Cyst-IgG4 ELISA kit the sensitivity and specificity of the DIGFA were higher slightly and there were no statistical differences according to chi-square criterion( x = 2.77, P > 0.05). Conclusions This new immunoassay for detection of specific IgG4 is not only rapid and simple but also sensitivitive and specificitive. It is very useful for clinical diagnosis and field investigation of cysticercosis cellulosae. Key words: Cysticercosis; IgG4; Immunogold filtration assay; Diagnosis