REOVIRUSES. II. STRUCTURE AND COMPOSITION OF THE VIRION.

Mayor, Heather D. (Baylor University College of Medicine, Houston, Tex.), Richard M. Jamison, Liane E. Jordan, and M. Van Mitchell. Reoviruses. II. Structure and composition of the virion. J. Bacteriol. 89:1548-1556. 1965.-Reovirus type 1 has been grown in green monkey kidney cells and harvested 24 hr after infection ("early" virus) and 96 hr after infection ("late" virus). A number of biological parameters have been determined on purified preparations of both "early" and "late" harvests of reovirus. There were no significant differences in values obtained for the molecular weight, RNA content, and buoyant density of virions prepared from early or late harvests. The size of the capsids and their morphology were also identical. Late harvests of reovirus were particularly rich in empty viral capsids (density, 1.28 in cesium chloride), and a significant number of empty inner capsid shells were routinely found. These shells could be prepared readily by controlled digestion of complete virus particles with trypsin. The inner shell appears to be composed of subunits packed with icosahedral symmetry to form a 45-mmu foundation on which the outer 92-subunit capsid is assembled. The inner shell is somewhat reminiscent in size and morphology of the capsid of papovaviruses. The fact that it can exist as a discrete entity has prompted us to propose some modifications to the current models for the reovirus capsid.