Evidence for a change in capsid morphology during Sindbis virus envelopment.

Sindbis virus nucleocapsids were isolated from intact virus particles and from the cytoplasms of infected cells. These two isolates of purified nucleocapsids differed from one another in ribonuclease sensitivity and in sedimentation velocity. These findings suggest that a conformational change takes place in the Sindbis virus nucleocapsid during envelopment.