Dyed particle capture immunoassay for detection of incipient brown-rot decay

An immunological method for detecting incipient fungal decay in wood is described. Monoclonal antibody to extracellular beta-1,4-xylanase of the brown-rot fungus Postia placenta was immobilized in a defined capture zone to a strip of hydrophobic polyester cloth. Polyclonal-labeled latex particles were applied near one end of the polyester assay substrate. The resulting test strip was dipped into extracts from wood blocks inoculated with various wood decay fungi. Extracts flowed laterally through the antibody-labeled latex particles and the capture zone. When antigen was present in the extract, the antigen was complexed by the monoclonal and labeled-polyclonal antibodies to form an observable particle complex in the zone of capture. Wood samples were tested at various stages of decay and correlated with wood weight loss. Incipient brown-rot decay was detected with the particle capture immunoassay at less than 2 percent wood weight loss.