Effect of Sodium Dextran Sulfate on Some Isometric Plant Viruses

Abstract

Nine isometric plant virus were treated with sodium dextran sulfate (NDS) at levels up to 20 .mu.g NDS/100 .mu.g virus (20% NDS/virus ratio) at pH 5.0 and at pH 7.5 with and without EDTA. None of the viruses were affected by NDS at pH 5.0. Turnip yellow mosaic and cowpea mosaic virus were unaffected by NDS under any of the conditions. Brome mosaic (BMV), carnation ringspot (CRSV) and turnip crinkle viruses (TCV) were affected by NDS at pH 7.5; tomato bushy stunt (TBSV), southern bean mosaic (SMBV), sowbane mosaic (SoMV) and turnip rosette viruses (TRosV) were affected at pH 7.5 only after treatment with EDTA. As increasing levels of NDS were used with BMV and CRSV, increasing amounts of the RNA were observed in sucrose density gradients until at a 20% NDS/virus ratio nearly all virus was dissociated. Insoluble isometric particles, formed of protein and NDS, and with diameters characteristic of T = 1 and T = 3 particles, were observed in these preparations by EM. Only 50% of the TCV or TBSV particles were dissociated at a 20% NDS/virus ratio and insoluble T = 1 particles were formed with TCV. The 3 sobemoviruses (SBMV, SoMV and TRosV) were dissociated into RNA by a 20% NDS/virus ratio, but at lower ratios soluble components were formed that sedimented at rates between those of swollen virus particles and RNA. Electron micrographs of these preparations showed T = 1, T = 3 and deformed particles as well as individual amorphous masses with highly irregular outlines. Swollen BMV was dissociated and its RNA and protein were separated by affinity chromatography on NDS-agarose columns by retention of the protein.