Detection of egg drop syndrome virus antigen or genome by enzyme-linked immunosorbent assay orpolymerase chain reaction

Abstract

Mouse monoclonal antibodies (mAbs) were produced against an Indian isolate of egg drop syndrome (EDS)virus and characterized. Four hybridoma clones were secreting mAbs that bound to a 100 kDa protein,presumably the hexon protein. These mAbs were found to cross-react with two other Indian isolates of EDSvirus and to the reference UK 127 strain. Three of these mAbs were mapped to the same epitope compared withthe other mAb (F8), which bound to a different epitope. An antigen-capture enzyme-linked immunosorbentassay (AC-ELISA) was developed using the F8 mAbs as capture antibody and polyclonal chicken serum againstEDS virus as detection antibody. A polymerase chain reaction (PCR) was used to detect the EDS viral genome.Following experimental infection of oestrogen-treated chickens with EDS virus, cloaca1 swabs, oviduct, uterusand spleen were collected at different days post-infection and used in both AC-ELISA and PCR, directly andafter a single passage in embryonated duck eggs. The sensitivity and specificity of antigen detection by ACELISAor PCR was 95% and 98%, respectively. For diagnosis of EDS viral infections, PCR is recommendeddue to its ease and the lack of requirement of prepared reagents such as mAbs or conjugates. We recommendthat PCR be performed directly on boiled tissue homogenates. Any negative samples may be passaged inembryonated duck eggs and the allantoic fluids tested by PCR before a conclusive negative diagnosis is given.