Structural Role of RNA in Semliki Forest Virus Nucleocapsid

Publisher Website
Google Scholar
Abstract
Semliki Forest virus nucleocapsids were isolated from purified virus; The nucleocapsids were variously treated with pancreatic ribonuclease and the effect of the treatment studied by sucrose gradient analysis and electron microscopy. After digestion of about 20 per cent of the nucleocapsid RNA the size of the particle had decreased from the original 39 nm to 32 nm. Heavy RNase treatment causing the loss of 50 per cent or more of the RNA did not affect the size much further. When examined by negative staining the small‐size nucleocapsid showed a layered structure with a central, stain resistant core of about 16 nm and an outer capsid‐like layer, 3 to 5 nm thick. Annular structures, 7 to 8 nm in diameter, were often discernible, but the structural symmetry of the capsid could not be established.