Particle Size of the MEF 1 Lansing Strain of Poliomyelitis Virus

Abstract

Summary and Conclusions

1. Using a Spinco preparative ultracentrifuge (Model L) a sedimentation constant of 163 S has been determined for the MEF¹ strain of poliomyelitis virus adapted to suckling mice. This sedimentation constant corresponds to a particle size of approximately 30 mμ 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. 2. 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. On the contrary such preliminary clarification, if anything, appeared to have increased the sedimentation constant of the virus. 3. The size calculated from results of the centrifugation experiments are in agreement with those obtained from electron photomicrographs and are probably closer to the correct value than those obtained by ultrafiltration.