Application of the negative staining-carbon technique to the study of virus particles and their components by electron microscopy

Abstract

The negative staining-carbon technique has been applied to a range of regular (icosahedral) and filamentous (helical) viruses. Under the preparative conditions used, it was demonstrated that the icosahedral particles formed large sheets of two-dimensional or three-dimensional crystalline arrays. Depending on the type of virus, physiological conditions and pH of the virus suspension in the presence of the negative stain solutions, the icosahedral particles could be packed into squares or hexagons. Rod-shaped or filamentous viruses at high concentrations were formed into aggregates extending over large areas with the particles arrange approximately in parallel array. Analysis of high resolution electron micrographs by optical diffraction showed that structural detail present in the images extended down to about 1.8 to 2.0nm. Evidence was obtained indicating the presence of protein and other material in monolayers at the specimen surface which restricted the amount of structural information which could be obtained.