Highly Purified Foot-and-Mouth Disease Virus: Optical and Biological Measurements during Zone Electrophoresis in a Glucose Density Gradient

Highly purified, concentrated foot-and-mouth disease virus, type A, was homogeneous and monodisperse by carrier-free zone electrophoresis in a glucose density gradient. Virus mobilities in veronal-acetate buffer, pH 8.6 and ionic strength 0.1, were identical whether determined by infectivity or optical methods. Low passage calf-kidney virus had a significantly higher mobility, 3.28 x 10 ~ 5 cm2/volt-sec, than high passage virus, 2.84 x 1 0 ~ 5 cm2/volt-sec. Single passages of the high passage virus in baby hamster kidney cells did not change its mobility. Regardless of passage history, storage at 4°C in 0.05 M phosphate at ph 7.5 increased mobilities to about 3.75 x 10-5 cm2/volt-sec with retention of infectivity; some virions broke down to protein and ribonucleic acid. These electrophoretically distinct viruses possessed different absorbance-temperature profiles but identical sedimentation constants.