Abstract:Monoclonal antibodies against mycoplasma-like organisms (MLO) associated with paulownia witches’broom (PWB) were produced by using partially purified preparations from diseased paulownia. Splenic cells from immunized mice were fused with sp2/0murine myeloma cells. Screened by indirect ELISA using partially purified PWB-MLO and healthy paulownia extracts as detecting antigens, two hybridoma clones that stably secreted specific antibodies against PWB-MLO were obtained from 459 clones of four successful fusions. The monoclonal antibodies were isotyped and determined to be immunoglubin classes IgG2a and IgG3. Antibody titers of ascitic fluids were both over 1.6 × 104 assayed by indirect ELISA. Priliminary application on several specimens proved that they were the monoclonal antibodies against PWB-MLO.