Isolation of a Macromolecular Constituent with Properties of the Lansing Strain of Poliomyelitis Virus.

Abstract

The freezing of ether-clarified, aqueous extracts of Lansing virus-infected cotton rat brains and spinal cords rendered insoluble 25-49% of the N present. After centri-fugation of the frozen and thawed extracts at low speed, a clear supernatant of the same or greater specific activity than the unfrozen extract was obtained. Further purification of the extracts by 3 or 4 cycles of differential ultra-centrifugation yielded purified virus samples with a range of specific activities in cotton rats expressed as I.D.50 of from 10-10.0 to 10-8.3 g. of virus n. This represented a 100- to 10,000-fold increase in specific activity over original clarified extracts. The purified virus was an amber-colored gel which was isotropic when viewed between crossed Nicol prisms. A soln. of this material showed no evidence of streaming birefringence. It gave a faint positive Millon''s test for protein and a positive test for carbohydrate. It was estimated on the basis of the relative yields of macromolecular N from extracts of normal and infected tissues that the amt. of normal macromolecular impurity present in purified virus prepns. was of the order of 5-20%. Purified virus samples showed a sedimentation rate of 83.5 = 7.33 S and were relatively monodisperse.