Studies on the Serodiagnosis of Bovine Cysticercosis by Enzyme-Linked Immunosorbent Assay

Abstract

The sensitivity and specificity of enzyme-linked immunosorbent assay (ELISA) for the diagnosis of Taenia saginata cysticercosis were studied in naturally infected and hyperimmune cattle sera using five different antigens. Fractions of excretory/=cercosis were studied in naturally infected and hyperimmune cattle sera using five different antigens. Fractions of excretory/secretory (ES-Ag) and homogenised metacestode components (Ho-Ag) of the parasite obtained from Sephadex G-200 colon chromatograhpy were unsatisfactory in the ELISA. Three of the antigenic fractions, designated Es-Ag, Ho-Ag and ThCF-crude (Taenia hydatigena cyst fluid crude antigen), cross reacted with common cattle parasites (Fasciola hepatica and Hydatid cyst). Among the five antigens, an ammonium sulfate-soluble fraction of Taenia hydatigena cyst fluid (ThFAS-L) was found to be the most reactive and this fraction was further evaluated for use in the immunodiagnosis of cysticercosis. With hyperimmune sera, ELISA detected the antibody response to T. saginata infection in cattle within four weeks after infection. The minimal detection level was approximately 100 live cysticerci in cattle. Among the naturally infected cattle, the senstivity of ELISA was poor, only 9 percent of the 44 proven cases was diagnosed. No negative sera gave false positive result. Within the limitations of this study, the high rate of false negative reactions suggested that ELISA is not a satisfactory procedure to dilagnose natural cysticercosis in cattle, at least in animals with weak infections. Protein patterns of the parasitic fractions were compared by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. SDS -PAGE indicated that ThFAS-L fraction was composed of high (MW 45.000 to 66.000) and low (MW 13.000 to 29.000) molecular weight proteins. Protein immunoblot analysis showed that a low molecular weight protein (MW 21.800) had a diagnostic significance. Other parasitic antigens did not show any reaction during immunoblotting procedure.