A PIONEER USAGE OF GOLD NANOPARTICLES IN SANDWICH ELISA BASED ON CIRCULATING HYDATID ANTIGEN AS A TOOL FOR IMPROVEMENT OF SERODIAGNOSTIC TESTING

Abstract

Human cystic echinococcosis is a zoonosis occurring due to dogs handling and exposure toEchinococcus granulosus ova in their stools being an accidental intermediate host. Serologyremains the only sure and important tool to diagnose this disease. We aimed to improve thedetection of circulating antigen by sandwich ELISA through its binding to gold nanoparticleand proving the role of minute nanoparticles in serodiagnosis. Gold nanoparticles (AuNPs)were employed for the capture of the antigens of protoscolices (pAg) in the patient’s serum bysandwich ELISA. Cross-reactivity for antigens from Hymenolepis nana, Entrobius vermicularis,and Fasciola gigantica was ruled out by using anti-protoscolices polyclonal IgG antibodies(ppAb). Antigen of sonicated protoscolices which were removed from camel lungcysts, was purified and injected to a New-zealand white rabbit giving ppAb which then loadedon AuNPs being used as a diagnostic indicator for circulating pAg by both sandwich ELISAand nanogold sandwich ELISA techniques. Nanogold sandwich ELISA was able to give positiveresults with 96.3% of hydatid patients and 5% of non-hydatid patients while sandwichELISA showed 81.4% and 20% positive cases of the same groups respectively. The sensitivityand specificity of nanogold sandwich ELISA were 96.3% & 95% against 81.5% & 80% forthose of sandwich ELISA respectively. The conjugation of AuNPs to anti-Echinococcus IgGantibodies seems to be beneficial to increase PPV, NPV, and efficiency and reduce the overallcost of the assay as less antibody was needed.