Improved Dot-ELISA Assay Using Purified Sheep Coenurus cerebralis Antigenic Fractions for the Diagnosis of Zoonotic Coenurosis

Abstract

Clinicians face significant problems in the diagnosis of zoonotic coenurosis. The current study aimed to develop an improved dot-Enzyme-linked-immunosorbent assay (dot-ELISA) for the diagnosis of zoonotic coenurosis using sheep Coenurus cerebralis scolices purified antigen (CcS-Ag) and to compare the obtained results with those of indirect ELISA and Enzyme-linked immunoelectrotransfer blot technique (EITB). Sera were collected from humans and sheep infected or suspected of infection with Coenurus cerebralis, control cases, and cases infected with other parasites. The CcS-Ag was proved to be the most specific antigen. This antigen was fractionated, and its specific polypeptides against anti-C. cerebralis antibodies (ACc-Ab) were identified using EITB. Fractions at the molecular weight (MW) of 48 and 58 kDa were proved as the only specific ones, eluted from the gel and concentrated, then dotted on the NC sheet as pooled antigen before its evaluation in the diagnosis of infection using dot-ELISA. Dot-ELISA demonstrated absolute 100% sensitivity and 100% specificity as recorded by EITB, compared to both fractions on a nitrocellulose (NC) sheet using surgically proved infected human or sheep sera as a gold standard. Diagnosis by ELISA using crude CcS-Ag revealed similar sensitivity but lower specificity (75%). The diagnostic accuracy of dot-ELISA was proved by comparing its results with postmortem data obtained post slaughtering of 20 suspected sheep and patients investigated by computed tomography (CT) and magnetic resonance imaging (MRI). In conclusion, the selection of specific fractions after EITB to be used in dot-ELISA improved the diagnostic value of the test as a diagnostic tool gathering the benefits of ELISA and EITB.