Abstract
A hitherto uncharacterized nucleoprotein sedimenting at 95S to 99S has been observed in preparations of six different isolates of strawberry latent ringspot virus when centrifuged in sucrose-density gradients. This component had the same coat protein composition, serological properties, size and outward aspect of particles as the rest of the virus and encapsidated a molecule of RNA-2, thus exhibiting all major characteristics of the middle (M) component of nepoviruses. One of the virus isolates under study, as well as two functional RNA species, appeared to possess a third satellite-like RNA with mol. wt. 0.45 x 106.