Monoclonal antibodies for the detection of spoilage fungi

Abstract

Monoclonal antibodies (M Abs) have proved useful in the development of immunoassays to detect the mycelium of specific fungi in foods and feeds. Development of M Ab-ELISA (enzyme-linked immunosorbent assay) and ‘user-friendly’ dip-stick assays for the detection of Humicola lanuginosa and Penicillium islandicum, involved in undesirable post-harvest discoloration of rice grains, is described briefly, as is a M Ab-ELISA for the detection of Botrytis cinerea in extracts from infected strawberries and grapes. These assays are sensitive, rapid, easily replicated and do not require surface sterilisation. The antigens, which are located on the surfaces and within the walls of the hyphae, are not present in the ungerminated spores of P. islandicum and are masked in aleurospores of H. lanuginosa, thus immunoassays for these fungi have the added advantage of detecting only mycelial growth. The most sensitive fungal M Abs are those that recognise heat-stable carbohydrate epitopes on carbohydrate or glycoprotein molecules. Difficulties in raising species-specific M Abs to fungi and particularly those related to choice of immunogen, are discussed.