Competitive ELISA using a rabies glycoprotein-transformed cell line to semi-quantify rabies neutralizing-related antibodies in dogs.

Dogs are the principal vectors for rabies virus transmission to humans in many parts of the world. The current "gold standard" World Health Organization- and Office International des Epizooties-recommended tests for measuring anti-rabies virus antibodies in dogs, such as the fluorescent antibody virus neutralization (FAVN) test, requires high containment facilities and several days for results. Here, we describe a new competitive ELISA (c-ELISA) that utilizes a cell line stably expressing the rabies virus glycoprotein as the coating antigen and two horseradish peroxidase-labeled monoclonal rabies-neutralizing antibodies as indicator, which can be carried out in any basic laboratory. We demonstrate that the c-ELISA has high specificity and sensitivity. Application to 4350 dog serum samples showed a parallel relationship with the FAVN at neutralizing antibody levels up to 8.00 IU/ml. Since it can assay 40 or more samples in 1.5h, the c-ELISA is suitable for the surveillance of mass vaccination in dogs where rabies causes public concern.