Development and evaluation of ELISA assays incorporating monoclonal antibodies for the detection of potato A potyvirus 1

Potato A potyvirus (PVA) was purified and used to immunize a balb/c mouse which had previously been rendered tolerant to plant sap. Three hybridoma-cell lines were selected which produced monoclonal antibodies Mab 58/6, Mab 58/7 and Mab 58/0. A rabbit polyclonal antiserum was also produced. The antibodies were incorporated in ELISA assays which were evaluated in field trials using potato leaf samples submitted for virus testing in support of the Scottish Seed Potato Classification Scheme in 1992/1993. An assay using Mab 58/6 as probe identified all PVA-positive samples during the test periods, but in 1991 a rare isolate was not detected by this assay. There was no cross reactivity with other viruses intercepted. An assay employing Mab 58/0 as coating antibody and conjugate also detected all PVA-positive samples during the test periods, but there was slight cross reactivity with PVYN and PVV. An indirect assay using polyclonal antibodies to coat and Mab 58/7 to probe detected 17 glasshouse-maintained PVA isolates, but in a field trial three out of 18 cases of PVA were not detected. There was no cross reactivity with other viruses intercepted.