Morphology of the California Encephalitis Virus (CEV)

Abstract

Negative staining technique with potassium phosphotungstate (pH 7.2) and thin sections stained with uranyl acetate (pH 4.2) and lead citrate (pH 11.0) were used to study the fine structure of the prototype strain, BFS-283, of the California encephalitis virus group. The BHK-21 cell line was employed in this study for virus propagation. Monolayers were infected using a multiplicity of infection of 0.1. Following virus adsorption the cells were incubated at 37 C for 48 or 72 hrs. at which times samples were harvested for electron microscopy.Conventional methods for virus concentration and purification (e.g. centrifugation, cesium chloride gradient centrifugation, dialysis) failed to yield intact virus particles. These preparations contained disintegrating virions averaging 75 nm in diameter (Fig. 1). Treatment of such purified preparations with a 1.0% solution of sodium desoxycholate removed the lipid envelope and associated material revealing a nucleocapsid core of approximately 43 nm (Fig. 2).