Increased Sensitivity of ELISA for Potato Viruses S, X, and Y by Polystyrene Pretreatments, Additives, and a Modified Assay Procedure. P. H. Goodwin, Graduate Student, 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. 68:944-947. Accepted for publication 19 June 1984. Copyright 1984 The American Phytopathological Society. DOI: 10.1094/PD-68-944.

The virus-specific absorbance (A₄₀₅) of enzyme-linked immunosorbent assay (ELISA) for potato viruses S, X, and Y (PVS, PVX, and PVY) was increased an average of 14.8% by pretreating new polystyrene cuvettes with 5.3 M NaOH:EtOH. Sodium diethyldithiocarbamate (0.01 M) in phosphate-buffered saline plus Tween 20 (PBS-T) increased the PVY-specific absorbance by 37.3% over that using a PBS-T control. Alkaline degradation of PVX by 0.2 M diethanolamine, pH 10.5, and 6–12% sodium sulfite increased the PVX-specific absorbance by 20.6% over that using PBS-T alone. Enhanced sensitivity was further characterized by regression analysis of the relationship between log A₄₀₅ and log/sap dilution. Dilution end points for virus detection were predicted from regression equations and corresponded to increases in the virus-specific absorbance using undiluted infected sap. A modified double-antibody sandwich ELISA increased the dilution end point for PVS detection by 30–32%, which was less than that previously reported with other plant viruses.