title: Development of monoclonal-antibody-ELISA and -DIP-STICK immunoassays for Penicillium islandicum in rice grains.
abstract: Monoclonal antibodies (mAbs) were raised against Penicillium islandicum, a fungus commonly isolated from stored rice grains in South-East Asia. Mice were immunized by a direct, simple method; fresh cell-free surface washings from a solid agar slant culture were injected directly into the peritoneum without prior concentration. Hybridoma supernatants were screened by ELISA. Most of the mAbs raised cross-reacted with other storage fungi and/or uninfected rice grains but there were species-specific. One of these, PI01, was used to develop ELISA and DIP-STICK assays for the detection of P. islandicum in individual grains. All inoculated grains and approximately 90% of grains in natural infected samples from Indonesia tested positively, by ELISA, for P. islandicum. This result and those obtained for discoloured grains from both Indonesia and the Philippines, 32% and 14% respectively, are higher than those obtained by direct plating of surface-sterilized grains. Heat and periodate treatment of the PI01 antigen and binding on Western blots indicate that it is a glycoprotein of Mr greater than 90,000. Hyphae of all ages stained uniformly by immunofluorescence using the PI01 antibody but mature conidia stained only weakly.
authors.affiliation: Department of Plant Sciences, University of Oxford, UK.
authors.forename: F M
authors.initials: FM
authors.lastname: Dewey
authors.forename: M M
authors.initials: MM
authors.lastname: MacDonald
authors.forename: S I
authors.initials: SI
authors.lastname: Phillips
authors.forename: R A
authors.initials: RA
authors.lastname: Priestley
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal; D000946:Antigens, Fungal / Q000032:analysis; D015153:Blotting, Western; D004591:Electrophoresis, Polyacrylamide Gel; D004797:Enzyme-Linked Immunosorbent Assay; D006358:Hot Temperature; D007118:Immunoassay; D007074:Immunoglobulin G / Q000276:immunology; D051379:Mice; D012275:Oryza / Q000382:microbiology*; D010407:Penicillium / Q000254:growth & development / Q000276:immunology / Q000302:isolation & purification*; D010504:Periodic Acid
chemical_list: D000911:Antibodies, Monoclonal; D000946:Antigens, Fungal; D007074:Immunoglobulin G; D010504:Periodic Acid; C009288:metaperiodate