Electron Microscopy of Maize Rough Dwarf Virus Particles

Summary The fine structure of maize rough dwarf virus (MRDV) has been studied by examining particles in ultrathin sections, crude extracts, and in purified preparations from diseased plants. The virus has a diameter of 65 to 70 nm. and contains a dense core of about 40 to 50 nm. diameter that is enveloped by a thin inner capsid 3 nm across. The outer capsid is about 10 nm. wide and 18 holes are seen on the perimeter. Smaller particles, 40 to 50 nm. in diameter are found in all types of preparations and some have incomplete outer capsids consisting of 12 isolated projecting structures that adhere to the inner capsids. Purified preparations contained only the incomplete particles. The structure of MRDV particles is compared to that of reoviruses.