Stability of ELISA Activity of Barley Yellow Dwarf Virus in Leaf Samples and Extracts. R. M. Lister, Professor, Department of Botany and Plant Pathology, Purdue University, West Lafayette, IN 47907. D. Clement and M. Skaria, Graduate Research Assistants, and J. A. McFatridge, Technical Assistant, Department of Botany and Plant Pathology, Purdue University, West Lafayette, IN 47907. Plant Dis. 69:854-857. Accepted for publication 20 May 1985. Copyright 1985 The American Phytopathological Society. DOI: 10.1094/PD-69-854.

Extraction and enzyme-linked immunosorbent assay (ELISA) detection of three isolates of barley yellow dwarf virus (P. PAV, MAV, and RPV), as tested over a range of ionic conditions, were optimal at pH 7 and 0.05–0.2 M. ELISA activity of extracts of the P. PAV and RPV isolates was well maintained during storage at –20 C or dialysis to 0.1 M phosphate at pH 7, but that of extracts of the MAV isolate was drastically reduced by these treatments, suggesting differences in stability or solubility between the isolates. In laboratory tests of leaves and in tests of leaf samples mailed worldwide, extractable ELISA activity for all three isolates survived storage better under a variety of conditions in dry leaves than in fresh leaves. Shipment of samples as dry leaves may have wider application in ELISA-based screening and survey programs for plant viruses and could obviate plant quarantine restrictions.