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Use of an Enzyme-Linked Immunosorbent Assay with Murine Ascitic Antibodies to Screen Microorganisms for Production of Cerato-ulmin, a Toxin of Ceratocystis ulmi. J. H. Nordin, Department of Biochemistry, University of Massachusetts, Amherst 01003; T. L. Mason(2), L. L. Smith(3), P. A. Willmann(4), W. C. Richards(5), and S. Takai(6). (2)(3)(4)Department of Biochemistry, University of Massachusetts, Amherst 01003; (5)(6)Great Lakes Forestry Centre, Canadian Forestry Service, P.O. Box 490, Sault Ste. Marie, Ontario P6A 5M7. Phytopathology 77:96-100. Accepted for publication 24 June 1986. Copyright 1987 The American Phytopathological Society. DOI: 10.1094/Phyto-77-96.

Polyclonal antibodies from hyperimmune ascitic fluid of mice immunized with cerato-ulmin (CU), a protein phytotoxin of Ceratocystis ulmi, have been utilized to develop a sensitive and specific assay to detect CU. As little as 20 Μg (1.5 picomoles) of CU per assay well can be detected by this method. Employing extracts of plate cultures of a number of microbial species, including many isolated from elm tissue, as well as several other Ceratocystis spp., we noted that only extracts of C. ulmi contained antibody-reactive material and that 56 of 86 C. ulmi isolates screened for CU production were positive. The ELISA was compared with a turbidimetric method for detecting CU production in both extracts of plate cultures and cell-free culture filtrates of 10 C. ulmi isolates. Isolates classified as either producers or nonproducers of CU by the ELISA using extracts of plate cultures were found to group in the same categories when culture filtrates were assayed by either the ELISA or turbidimetry.