The production and characterization of monoclonal antibodies againstalternaria brassicae(berk.) sacc., the cause of dark leaf and pod spot in oilseed rape

Abstract

Monoclonal antibodies (MAbs) were raised against homogenized spore germlings of Alternaria brassicae. SP2/0‐Agl4 myeloma cells were fused with sensitized splenocytes 48 h after the final boost with antigen. Twelve cell lines produced antibodies which recognized the isolate used for immunization and a number of A. brassicae isolates from different parts of the world. However, only two cell lines, MAbs 34/7VG (igGi) and 73/11/D (IgG₁/IgM), were found to be species and isolate specific respectively for A. brassicae when tested against 19 isolates of related and non‐related fungi representing 13 fungal genera. Both species‐specific antibodies recognized proteinaceous epitopes. A good correlation between the optical density in ELISA and the number of spores per well was found for antigen concentrations between 5 and 400 spore germlings per well, when testing MAb 34/7/G in an indirect, alkaline phosphatase‐based ELISA. Results of wind tunnel experiments in which airborne A. brassicae spores were collected into ELISA wells showed a good correlation between the spore number when counted and the predicted spore number when estimated by MAb 34/7/G in ELISA tests.