The fine structure of vesicular stomatitis virus

Abstract

The structure of bullet-shaped (B) and truncated (T) particles of vesicular stomatitis virus was examined by electron microscopy using negative staining and thin sectioning techniques. The conformation of the internal, probably nucleoprotein, component in intact and disintegrating particles was investigated, and the following conclusions were reached. The nucleoprotein is in the form of a ribbonlike strand consisting of a series of regular rodlike subunits of dimensions approximately 90 A × 30 A × 30 A; the continuity of the strand is presumably maintained by the subunits being attached to a thread of nucleic acid. In the intact virion, the strand is in the form of a helix of about 30 coils of external diameter 490 A, plus about 4 coils of diminishing diameter which form a hemispherical cap at one end. In the helix the long axis of the subunits is radially orientated. In disintegrating particles the helix unwinds to form an undulatory ribbon which may assume the configuration of an irregular helix of diameter approximately half that of the original helix. The distribution of lengths of isolated strands obtained from disintegrated virions was determined and a value of 3.4 to 3.8 × 10 6 daltons deduced for the molecular weight of the viral RNA. The T particles were investigated in the same way. Except for their much shorter length they appeared to be identical to B particles. The molecular weight of the RNA of T particles was estimated to be 1.1 × 10 6 daltons.