Dot-ELISA on Nitrocellulose Membranes for Detection of Potato Leafroll Virus. F. D. Smith, Research Assistant, Department of Plant Pathology, University of Minnesota, St. Paul 55108. E. E. Banttari, Professor, Department of Plant Pathology, University of Minnesota, St. Paul 55108. Plant Dis. 71:795-799. Accepted for publication 4 April 1987. Copyright 1987 The American Phytopathological Society. DOI: 10.1094/PD-71-0795.

Potato leafroll virus (PLRV) was consistently detected by dot-ELISA in buffer extracts of PLRV-infected potato foliage sap diluted 1:2,048 with buffer extracts of healthy foliage sap. The assay procedure used a double-antibody sandwich, alkaline phosphatase and naphthol ASMX phosphate, and fast red TR salt substrate on Millipore 0.45-µm nitrocellulose membranes (NCM). Potato sap extracts heated at 70 C for 10 min improved sap drainage through the NCM, decreased nonspecific staining, and increased sensitivity. Membranes precoated with anti-PLRV IgG and stored for 1 wk at 4 C retained reaction sensitivity and permitted assay completion within one working day. Dot-ELISA for PLRV in potato leaves was eight times more sensitive than double-antibody sandwich (DAS) ELISA in polystyrene cuvette paks and twice as sensitive as DAS-ELISA in microtiter plates.