Physicochemical studies of equine infectious anemia virus

Summary A purification procedure for equine infectious anemia (EIA) virus has been developed by combining ultracentrifugation, DEAE cellulose column chromatography and cesium chloride equilibrium density gradient centrifugation. Recovery and purity of the virus were determined at each step of the purification procedure. Using this combined method, an amount of purified and concentrated virus was prepared from a large volume of virus material. Such specimens showed an infectivity of 10^8.25 TCID₅₀/0.5 ml, a complement fixing antigenicity of 80 density of 1.146 g/ml, and proved to be suitable for electron microscopic observation of negatively stained preparations.Most of the virus particles had a spherical shape and sized between 90 and 140 m, in diameter. A well-defined outer envelope was observed in spontaneously disrupted particles, but no organized internal component could be resolved.