Vesicular stomatitis virus was extracted with 60 mM
octylglucoside in the absence of
salts and in the presence of 0.5 M NaCl. The resulting extracted virus particles were examined by electron microscopy, and the
proteins present were identified by
sodium dodecyl sulfate-
polyacrylamide gel electrophoresis. Extraction in the absence of
salts yielded subviral structures which we cell "skeletons" as originally suggested by Cartwright et al. (J. Gen. Virol. 7:19-32, 1970). The skeletons contained the viral N, M, and L
proteins, but they lacked the
glycoprotein (G) entirely. Morphologically, the skeletons resembled intact
vesicular stomatitis virus but they were slightly longer and smaller in diameter. Like native
vesicular stomatitis virus, skeletons were found to have lateral striations spaced 5.0 to 6.0 nm apart along the length of the structure. In contrast to extraction in the absence of NaCl, extraction of
vesicular stomatitis virus with 60 mM
octylglucoside in the presence of 0.5 M NaCl yielded highly extended viral nucleocapsids in which N was the predominant
protein; no M or
G proteins could be detected. These results support the view that the M
protein is involved in maintaining the nucleocapsid in the compact form found in native virions.