Lengths and structure of particles of barley strips mosaic virus

Preparations of barley stripe mosaic virus contain a major component with a sedimentation coefficient of 189 S and three minor components with sedimentation coefficients of 180, 199, and 250 S, respectively. Mounts in phosphotungstate show particles ranging in length from 20 to 280 mμ, but the commonest length is 128 mμ and frequency distribution diagrams show two other peaks at 111 and 148 mμ. These three particle lengths probably correspond with the three components sedimenting at 180, 189, and 199 S, and the 250 S component may indicate aggregation of these particles in pairs. Particles shorter than 111 mμ were not infective; whether infectivity is restricted to particles with one of the three commonest lengths or is common to all could not be determined because the three could not be separated from one another. When mounted in phosphotungstate a few particles show a loose helical structure.