Particle Size of the MEF1 Lansing Strain of Poliomyelitis Virus

Abstract

Using a Spinco preparative ultracentrifuge (Model L) a sedimentation constant of 163 S was detd. for the MEF strain of poliomyelitis virus adapted to suckling mice. This sedimentation constant corresponds to a particle size of approx. 30 mu when a particle density of 1.33 g./cc. is assumed. This size is larger than that previously reported especially by investigators using ultrafiltration technics. The high sedimentation constant is apparently not due to adsorption of the virus to tissue fragments. Thus, preliminary clarification by ether and tryptic digestion did not reduce the speed of sedimentation of the virus during centrifugation. Such preliminary clarification appeared to have increased the sedimentation constant of the virus. The size calculated from results of the centrifugation expts. agree with those obtained from electron photomicrographs and are probably closer to correct value than those obtained by ultrafiltration.