Glycoprotein gE blocking ELISAs to differentiate between Aujeszky's disease-vaccinated and infected animals

Three blocking ELISAs for the detection of antibodies against glycoprotein E (gE) of Aujeszky's disease virus (ADV) in sera (an indirect blocking ELISA (gE-iELISA), a direct blocking ELISA (gE-dELISA) and a two-site 'sandwich' blocking ELISA (gE-sELISA)) have been developed. The gE-ELISAs are based on monoclonal antibodies (mAbs) directed to gE and detect gE-specific antibodies in sera by blocking the binding of mAbs to one (in the gE-iELISA and the gE-dELISA) or two (in the gE-sELISA) epitopes of gE. From a panel of thirteen gE-specific mAbs, mAbs, their conjugates and the combination coating mAb/conjugate that optimally detect anti-gE antibodies in the assays were selected. Sera from uninfected unvaccinated swine or swine vaccinated against different swine viral disorders were negative by three gE-ELISAs, the blocking gB-ELISA, and VNT. Swine vaccinated with gE-negative vaccine were seropositive in the gB-ELISA and VNT but were seronegative by three gE-ELISAs. Infected unvaccinated swine, infected swine vaccinated with gE-negative vaccine, and swine vaccinated with gE-positive vaccine were detected as seropositive by three gE-ELISAs as well as in the gB-ELISA. The gE-dELISA and the gE-sELISA proved to be specific and the most sensitive and reliable assays to distinguish ADV-infected swine from those vaccinated with gE-negative vaccine. These two gE-ELISAs were at least as sensitive as the gB-ELISA for detecting ADV-specific antibodies.