Purified virus from each sample preparation after purification was evaluated by negative staining. In addition, virus was recovered from membranes after aphids fed for 24 h to assess the stability of the virus. 300 Mesh copper carbon-coated formvar grids were incubated for 30 min on a 10 ml drop of RPV coating antibody diluted 1:500 in phosphate buffered saline (PBS). Excess antibody was wicked off with a wedge of filter paper and grids were rinsed in 3 drops of PBS, wicking off excess with filter paper after each rinse. Antibody-coated grids were incubated for 1 h on a 10 ml drop of virus. Virus was wicked off using filter paper and grids were rinsed in 2 drops of PBS, followed by 3 drops of sterile distilled water, wicking excess after each rinse. Grids were stained by incubating for 3 min on a 20 ml drop of 2% aqueous uranyl acetate, excess stain was wicked off and grids were stored dry in a grid box. Grids were viewed on a Jeol 1200 TEM at the Electron Microscope Facility for The Huck Institute of the Life Sciences at The Pennsylvania State University.