Some characteristics of monoclonal antibodies to a British M A V‐like isolate of barley yellow dwarf virus

Rat monoclonal antibodies (MAbs) specific for a British F (MAV‐like) isolate of barley yellow dwarf virus (BYDV) were produced and studied. In indirect ELISA using an antiserum to BYDV‐F to trap virus from infected sap, the MAbs were shown to be specific for MAV‐like isolates of BYDV from Britain, USA and Sweden but, in this test, they did not detect PAV‐, RPV‐, SGV‐ or RMV‐ like isolates of BYDV. In similar tests using homologous antisera to trap the viruses, the MAbs did not detect BYDV‐PAV or ‐RPV or two other luteoviruses (potato leafroll and beet western yellows). One of the MAbs (MAFF 2) was partially purified from ascitic fluid, and used successfully in ELISA as a coating antibody and when conjugated to the enzyme alkaline phosphatase. Also, MAFF 2 successfully trapped BYDV‐F particles when used to coat electron microscope grids. In indirect ELISA using three MAbs (MAFF 2, MAC 91 and MAC 92) it was possible to type the three major strain groups of BYDV, viz. MAV, PAV and RPV‐like strains from Britain, USA and Europe.