Direct Antigen Coating DAC ELISA - In this direct antigen coating (OAC) technique, plant extracts prepared in a carbonate buffer are applied directly to the wells.

In the second step, diluted unfractionated antiserum is added. Ig attached to virus antigen is detected by the addition of enzyme-Ig conjugates. This is the simplest procedure and can be completed within three hours. With 96 wells in a plate, as many as 16,000 seeds could be tested in a day. This procedure, however, is not suitable for quantitative estimations, due to the use of crude extract.